JP6361518B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery using the same - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery using the same.

  Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are being put to practical use in a wide range of applications from so-called consumer power sources such as mobile phones and notebook computers to in-vehicle power sources for automobiles and the like. However, the demand for higher performance for non-aqueous electrolyte secondary batteries in recent years has been increasing, and in particular, there are various types such as high capacity, low temperature use characteristics, high temperature storage characteristics, cycle characteristics, and overcharge safety. There is a demand for improved battery characteristics.

  The electrolyte used for the non-aqueous electrolyte secondary battery is usually composed mainly of an electrolyte and a non-aqueous solvent. The main components of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone. It is used.

In order to improve battery characteristics such as load characteristics, cycle characteristics, storage characteristics, etc. of such non-aqueous electrolyte secondary batteries, and to improve battery safety during overcharge, various non-aqueous solvents, electrolytes, and additives are used. Consideration has been made.
In Patent Documents 1 to 10, by mixing aromatic esters such as methyl benzoate, ethyl benzoate, phenyl propionate, phenyl acetate, and benzyl acetate in the electrolytic solution, the energy density of the battery, long-term durability, high temperature Methods for improving storage gas suppression and low temperature characteristics have been proposed.

Patent Document 11 proposes a technique for improving the safety of a battery during overcharge by using an electrolytic solution to which a specific carboxylic acid aromatic ester is added.
Patent Document 12 proposes a technique for suppressing battery swelling during high-temperature storage without reducing battery capacity by including a specific carboxylic acid aromatic ester compound in a non-aqueous electrolyte.

Japanese Patent No. 0463407 Japanese Patent No. 0383627 Japanese Patent Laid-Open No. 10-255836 JP 2000-268831 A JP-A-2005-347222 Japanese Patent No. 0963898 Japanese Patent No. 4051947 JP 2001-297790 A JP 2002-033121 A JP 2003-338277 A JP 2000-058112 A JP 2000-173650 A WO2014 / 003165 publication

  Non-aqueous electrolyte secondary batteries using an electrolytic solution containing a compound having both an aromatic group and an ester group described in Patent Documents 1 to 13 have an initial capacity and efficiency from the high reactivity of the compound. The problem is that it is difficult to simultaneously improve the initial battery characteristics such as the rate characteristics and the initial gas amount and the battery characteristics after the endurance test such as the capacity, efficiency, rate characteristics and safety during overcharge after storage at high temperature. was there.

  The present invention has been made to solve the above problems, and in a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte that simultaneously improves initial battery characteristics and battery characteristics after a durability test, and the non-aqueous electrolyte It is an object to provide a non-aqueous electrolyte secondary battery using an electrolyte.

As a result of various studies to achieve the above object, the present inventors have found that the above-mentioned problems can be solved by including a specific aromatic carboxylic acid ester in the electrolytic solution, and the present invention has been completed. I came to let you.
Moreover, it discovered that the said subject could be solved by containing a specific aromatic carboxylic acid ester and a specific additive in electrolyte solution, and came to complete this invention.

The gist of the present invention is as follows.
(I) A non-aqueous electrolyte solution for a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting metal ions, the non-aqueous electrolyte solution together with an electrolyte and a non-aqueous solvent,
(I) Formula (1):

(Where
A ² is an aryl group which may have a substituent,
n ² is an integer of 1 or 2,
a ² is an integer of 1 or 2,
When a ² is 1, R ⁴ is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an aryl group which may have a substituent, However, when n ² is 2, R ⁴ is an aryl group which may have a substituent,
when a ² is 2, R ⁴ is a single bond, an aliphatic hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an arylene group which may have a substituent; A plurality of A ² may be the same or different, provided that when n ² is 2, R ⁴ is an arylene group which may have a substituent)
An aromatic carboxylic acid ester represented by:
(II) Fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphonic acid ester, organic compound having cyano group, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (1), formula (3):

Where
R ⁵ is a hydrocarbon group having 1 to 4 carbon atoms,
R ⁶ is a carboxylic acid ester represented by being an ethyl group, an n-propyl group or an n-butyl group, a cyclic compound having a plurality of ether bonds, a monofluorophosphate, a difluorophosphate, a borate, A non-aqueous electrolyte containing at least one compound selected from the group consisting of oxalates and fluorosulfonates. (Ii) The non-aqueous electrolyte solution according to (i), wherein a ² is 1 in the formula (1).
(Iii) The nonaqueous electrolytic solution according to (i) or (ii), wherein A ² is a phenyl group in the formula (1).
(Iv) Any of (i) to (iii), wherein the non-aqueous electrolyte contains the aromatic carboxylic acid ester represented by the formula (1) in an amount of 0.001% by mass to 10% by mass. The non-aqueous electrolyte solution described in one.
(V) The non-aqueous electrolyte includes a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphonic acid ester, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, and an aroma other than the formula (1) Group compound, carboxylic acid ester represented by the formula (2), cyclic compound having a plurality of ether bonds, monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate The non-aqueous electrolyte solution according to any one of (i) to (iv), which contains at least one compound selected from the group in an amount of 0.001% by mass to 20% by mass.
(Vi) A non-aqueous electrolyte secondary battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte solution is a claim (i) A non-aqueous electrolyte secondary battery, which is the non-aqueous electrolyte solution according to any one of (1) to (v).

ADVANTAGE OF THE INVENTION According to this invention, the non-aqueous electrolyte solution which can bring about the non-aqueous electrolyte secondary battery excellent in the initial battery characteristic and the battery characteristic after an endurance test can be provided, and a non-aqueous electrolyte secondary battery can be provided. Can be reduced in size, performance and safety.
The non-aqueous electrolyte secondary battery produced using the non-aqueous electrolyte of the present invention and the non-aqueous electrolyte secondary battery of the present invention simultaneously improve the initial battery characteristics and the battery characteristics after the durability test.・ The principle is not clear, but it is considered as follows. However, the present invention is not limited to the operations and principles described below.

Usually, aromatic carboxylic acid esters and carboxylic acid aromatic esters represented by Patent Documents 1 to 13 improve the battery characteristics by forming a film-like structure on the positive electrode. However, the aromatic carboxylic acid ester in which the oxycarbonyl group is directly bonded to the aromatic ring described in Patent Documents 1 to 10 and the carboxylic acid aromatic ester in which the carbonyloxy group is directly bonded to the aromatic ring are the aromatic ring and the carbonyl group. When the vacant orbitals overlap, the reduction side reaction at the negative electrode proceeds remarkably, and a film having a low Li ⁺ conductivity is formed in a large amount. As a result, the charge / discharge characteristics and charge / discharge efficiency under a high current density can be greatly reduced. In addition, the discharge capacity can be greatly reduced due to the remarkable progress of the reduction side reaction.

In addition, in the phenylacetate esters described in Patent Documents 11 and 12, since the carbonyl group and the aromatic ring are located at a short distance via the methylene group, the vacant orbits overlap as in the case of the aforementioned compound. As a result, the reduction side reaction at the negative electrode proceeds, and the battery characteristics can be deteriorated similarly to the compounds described in Patent Documents 1 to 10.
Further, in Patent Document 13, an attempt is made to improve the above-mentioned problems by using an aromatic carboxylic acid ester inferior in reduction resistance and a specific additive in combination. Oxidation resistance is low, side reactions occur on the positive electrode at normal operating voltages, and battery characteristics can be greatly degraded.

  On the other hand, a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphonic acid ester, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, an aromatic compound other than the above formula (1), and the above formula (2) At least one compound selected from the group consisting of a carboxylic acid ester, a cyclic ether, a monofluorophosphate, a difluorophosphate, a borate, an oxalate, and a fluorosulfonate ("(II) Group of compounds ") forms a film on the negative electrode and improves performance. However, at the same time, deterioration due to an oxidation side reaction on the positive electrode also proceeds, so that improvement of battery characteristics by adding only these was insufficient.

In order to solve such a problem, the present invention can solve the above problem by simultaneously containing the aromatic carboxylic acid ester represented by the formula (1) and the compound of the group (II) in the non-aqueous electrolyte solution. I found it.
When the aromatic carboxylic acid ester represented by the formula (1) is overlapped with the vacancies of the aromatic ring of the carboxylic acid skeleton and the vacant orbital of the carbonyl group, the reduction side reaction at the negative electrode proceeds when used alone, and Li ⁺ conductivity It is believed that a large amount of low film is formed. On the other hand, when the aromatic carboxylic acid ester represented by the formula (1) and the compound of the group (II) are used at the same time, the film formed by the compound of the group (II) on the negative electrode is represented by the formula (1). The reduction side reaction of the aromatic carboxylic acid ester is suppressed. Further, when the compound of the group (II) forms a film on the negative electrode, a part of the aromatic carboxylic acid ester represented by the formula (1) is taken in, so that a composite film having a high Li ⁺ conductivity and a stable property is obtained. Form. On the positive electrode, the aromatic carboxylic acid ester represented by the formula (1) forms a film-like structure, thereby suppressing the oxidation side reaction of the compound of the group (II). As a result, the initial battery characteristics and the battery characteristics after the durability test can be improved at the same time without deteriorating the battery characteristics.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments, and can be arbitrarily modified without departing from the gist of the present invention.
1. Non-aqueous electrolyte 1-1. Aromatic carboxylic acid ester represented by formula (1) A second aspect of the present invention is characterized in that the non-aqueous electrolyte contains the aromatic carboxylic acid ester represented by formula (1). In the aromatic carboxylic acid ester represented by the formula (1), optical isomers cannot be distinguished, and the isomers can be used alone or as a mixture thereof.

(Where
A ² is an aryl group which may have a substituent,
n ² is an integer of 1 or 2,
a ² is an integer of 1 or 2,
When a ² is 1, R ⁴ is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an aryl group which may have a substituent, However, when n ² is 2, R ⁴ is an aryl group which may have a substituent,
when a ² is 2, R ⁴ is a single bond, an aliphatic hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an arylene group which may have a substituent; A plurality of A ² may be the same or different. However, when n ² is 2, R ⁴ is an arylene group which may have a substituent. )
In Formula (1), R ⁴ and A ² are not bonded to each other to form a ring.

In Formula (1), when a ² is 1, R ⁴ is a hydrogen atom, an aliphatic hydrocarbon group (monovalent group) having 1 to 12 carbon atoms that may have a substituent, or a substituent. An aryl group which may have
Here, the substituent is a group composed of one or more atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms and halogen atoms (however, carbon atoms and hydrogen atoms Represents a group composed only of

  As the substituent, a halogen atom (preferably a fluorine atom); an alkoxy group; an alkyl group, an alkenyl group, an alkynyl group, an aryl group or an alkoxy group substituted with a halogen atom (preferably a fluorine atom); a cyano group, an isocyanato Group, alkoxycarbonyloxy group; acyl group; carboxy group; alkoxycarbonyl group; acyloxy group; alkylsulfonyl group; alkoxysulfonyl group; dialkoxyphosphantriyl group; dialkoxyphosphoryl group and dialkoxyphosphoryloxy group , Preferably a halogen atom or an alkyl group substituted with a halogen atom, more preferably a halogen atom or an alkyl group substituted with a halogen atom. Examples of the alkyl group and alkoxy group in the above substituent (including those constituting a part of the substituent) include those having 1 to 6 carbon atoms, and examples of the alkenyl group and alkynyl group include carbon atoms. Examples of the aryl group include those having 6 to 12 carbon atoms.

The number of carbon atoms in the aliphatic hydrocarbon group (monovalent group) is preferably 10 or less, more preferably 9 or less, and still more preferably 5 or less.
Examples of the aliphatic hydrocarbon group (monovalent group) include an alkyl group, an alkenyl group, and an alkynyl group.
Among these, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec- Pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group and other alkyl groups having 1 to 5 carbon atoms, vinyl group, 1-propenyl group, 2 to 5 carbon atoms such as 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group and 4-pentenyl group Alkenyl group, ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl C2-C5 alkynyl groups such as 3-pentynyl group and 4-pentynyl group are preferred, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group An alkyl group having 1 to 5 carbon atoms such as a group is more preferable, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group are further preferable, and a methyl group and an ethyl group are particularly preferable.

The aliphatic hydrocarbon group may have a substituent, but is preferably unsubstituted.
The aryl group is not particularly limited, but may have 6 or more carbon atoms, preferably 7 or more, more preferably 8 or more, and 12 or less, preferably 11 or less, more preferably 10 or less.
As the aryl group, phenyl group, tolyl group, ethylphenyl group, n-propylphenyl group, i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl group And xylyl group. An aryl group having a halogen atom (preferably a fluorine atom) or an unsubstituted or halogen atom (preferably fluorine atom) -substituted alkoxy group as a substituent is also preferable. Examples thereof include a phenyl group, a trifluoromethoxyphenyl group, a monofluorophenyl group, a difluorophenyl group, a trifluorophenyl group, a tetrafluorophenyl group, a pentafluorophenyl group, and a hexafluorophenyl group. Among these, a phenyl group, a tolyl group, a tert-butylphenyl group, a methoxyphenyl group, and a monofluorophenyl group are preferable, a phenyl group and a tolyl group are more preferable, and a phenyl group is still more preferable.

When a ² is 1, R ⁴ is preferably a hydrogen atom or an aliphatic hydrocarbon group (monovalent group) having 1 to 12 carbon atoms which may have a substituent, more preferably hydrogen. An atom or an unsubstituted aliphatic hydrocarbon group having 1 to 12 carbon atoms (monovalent group), more preferably a hydrogen atom. However, when n ² is 2, R ⁴ is an aryl group which may have a substituent, and is preferably an unsubstituted aryl group.

In Formula (1), when a ² is 2, R ⁴ is a single bond, an aliphatic hydrocarbon group (divalent group) having 1 to 12 carbon atoms which may have a substituent, or a substituent. An arylene group which may have
Examples of the aliphatic hydrocarbon group (divalent group) include a divalent group corresponding to the group exemplified as the aliphatic hydrocarbon group (monovalent). Among them, alkylene groups having 1 to 5 carbon atoms such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene. Group, carbon having 2 to 5 carbon atoms such as 1-pentenylene group, 2-pentenylene group, ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group. An alkynylene group of 2 to 5 is preferable.

Examples of the arylene group include divalent groups corresponding to the groups exemplified as the aryl group. Of these, a phenylene group and the like are preferable.
When a ² is 2, R ⁴ is preferably an aliphatic hydrocarbon group (divalent group) having 1 to 12 carbon atoms which may have a single bond or a substituent, and more preferably It is a single bond or an unsubstituted aliphatic hydrocarbon group (divalent group) having 1 to 12 carbon atoms. However, when n ² is 2, R ⁴ is an arylene group which may have a substituent, and preferably an unsubstituted arylene group.

In the formula (1), A ² is an aryl group which may have a substituent. Examples of the substituent include the groups exemplified for R ⁴ . The aryl group is not particularly limited, but the number of carbon atoms can be 6 or more, preferably 7 or more, more preferably 8 or more, and 12 or less, preferably 11 or less, more preferably Is 10 or less. As the aryl group, phenyl group, tolyl group, ethylphenyl group, n-propylphenyl group, i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl group And xylyl group. An aryl group having a halogen atom (preferably a fluorine atom) or an unsubstituted or halogen atom (preferably fluorine atom) -substituted alkoxy group as a substituent is also preferable. For example, a trifluoromethylphenyl group, a xylyl group, a methoxyphenyl group, an ethoxy group Examples thereof include a phenyl group, a trifluoromethoxyphenyl group, a monofluorophenyl group, a difluorophenyl group, a trifluorophenyl group, a tetrafluorophenyl group, a pentafluorophenyl group, and a hexafluorophenyl group. Among these, a phenyl group, a tolyl group, a tert-butylphenyl group, a methoxyphenyl group, and a monofluorophenyl group are preferable, a phenyl group and a tolyl group are more preferable, and a phenyl group is still more preferable.

In the formula (1), n ² is preferably 1. In the formula (1), a ² is preferably 1.
Examples of the aromatic carboxylic acid ester represented by the formula (1) include the following compounds.
<< when a ² = 1 >>
In the case of a ² = 1, in the following compounds exemplified as specific examples, R represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, i -Butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group ,, Phenyl group, tolyl group, tert-butylphenyl group, methoxyphenyl group, monofluorophenyl group, R ′ is a phenyl group, tolyl group, tert-butylphenyl group, methoxyphenyl group, mono An aryl group selected from a fluorophenyl group.

<< when a ² = 2 >>
When a ² = 2, in the following compounds mentioned as specific examples, R is a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a vinylene group, a 1-propenylene group, a 2-propenylene group, Hydrocarbon selected from 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group, ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group It is a group.

Of these, the following compounds are preferred from the viewpoint of reducing the reduction side reaction on the negative electrode.

Further, among these, the following compounds are more preferable from the viewpoint of few oxidation side reactions on the positive electrode.

The aromatic carboxylic acid ester represented by the formula (1) may be used alone or in combination of two or more. In the total amount (100% by mass) of the non-aqueous electrolyte solution, the amount of the aromatic carboxylic acid ester represented by the formula (1) (the total amount in the case of two or more types) can be 0.001% by mass or more. , Preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less. More preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less, Most preferably, it is 2.5.
It is below mass%. By being in the said range, the effect of this invention is easy to express and the resistance increase of a battery can be prevented.

  In addition, the method of mix | blending the said compound with the electrolyte solution of this invention is not restrict | limited in particular. In addition to the method of directly adding the compound to the electrolytic solution, a method of generating the compound in the battery or in the electrolytic solution can be mentioned. Examples of a method for generating the compound include a method in which a compound other than these compounds is added to generate a battery component such as an electrolytic solution by oxidation or hydrolysis. Furthermore, a method of generating a battery by applying an electrical load such as charge / discharge is also mentioned.

1-2. Compound of Group (II) The second aspect of the present invention is an organic compound having a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphonic acid ester, and a cyano group together with the aromatic carboxylic acid ester represented by the above formula (1). Compound, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (1), carboxylic acid ester represented by formula (2), cyclic compound having a plurality of ether bonds, monofluorophosphate, It is characterized in that at least one compound selected from the group consisting of difluorophosphate, borate, oxalate and fluorosulfonate (compound of group (II)) is contained in the non-aqueous electrolyte. . It is because the side reaction that can be caused by the aromatic carboxylic acid ester represented by the formula (1) can be efficiently suppressed by using these in combination.

  Among them, fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphonic acid ester, organic compound having cyano group, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (1), and formula (2) And at least one compound selected from the group consisting of carboxylic acid esters, monofluorophosphates, difluorophosphates, borates, oxalates, and fluorosulfonates, has a good composite coating on the negative electrode. Formed, preferably because the initial battery characteristics and the battery characteristics after the durability test are improved in a good balance, fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphonic acid ester, organic compound having a cyano group, organic compound having an isocyanate group, Silicon-containing compound, aromatic compound other than formula (1), carvone represented by formula (2) More preferably, at least one compound selected from the group consisting of esters, monofluorophosphates, difluorophosphates, oxalates and fluorosulfonates, fluorine-containing cyclic carbonates, sulfur-containing organic compounds, phosphonates, Group consisting of organic compound having cyano group, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (1), monofluorophosphate, difluorophosphate, oxalate and fluorosulfonate More preferably, at least one compound selected from the group consisting of a sulfur-containing organic compound, a phosphonic acid ester, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, a monofluorophosphate, a difluorophosphate, From oxalate and fluorosulfonate At least one compound selected from the group is particularly preferred. The reason for this is that these compounds that form a relatively low molecular weight film on the negative electrode have a dense negative electrode film, and thus the side reaction of the aromatic carboxylic acid ester represented by the formula (1) efficiently. It can be mentioned that deterioration due to can be suppressed. In this way, side reactions are effectively suppressed, resistance increases are suppressed, volume changes are suppressed by suppressing side reactions during initial and high temperature durability, and safety after high temperature durability is secured, and rate characteristics are improved. obtain.

The method for blending the above compound with the electrolytic solution of the present invention is not particularly limited. In addition to the method of directly adding the compound to the electrolytic solution, a method of generating the compound in the battery or in the electrolytic solution can be mentioned. Examples of a method for generating the compound include a method in which a compound other than these compounds is added to generate a battery component such as an electrolytic solution by oxidation or hydrolysis. Furthermore, a method of generating a battery by applying an electrical load such as charge / discharge is also mentioned.
Below, the compound of the (II) group is demonstrated. However, regarding monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate, 1-3. The explanation in the electrolyte applies.

1-2-1. Fluorine-containing cyclic carbonate Examples of the fluorine-containing cyclic carbonate include a fluorinated product of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. And derivatives thereof. Examples of the fluorinated derivative of ethylene carbonate include fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Of these, fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof are preferred.

In the electrolytic solution of the present invention, by using the aromatic carboxylic acid ester represented by the formula (1) and the fluorine-containing cyclic carbonate in combination, in the battery using this electrolytic solution, the initial gas amount can be suppressed, Battery safety can be further improved by increasing the amount of overcharge gas.
Examples of the fluorinated ethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4, 5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene Carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethyl Le ethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

Among these, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferable because they give high ionic conductivity to the electrolyte and easily form a stable interface protective film.
A fluorinated cyclic carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. The amount of the fluorinated cyclic carbonate (total amount in the case of 2 or more types) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% in 100% by mass of the electrolytic solution. % By mass or more, still more preferably 0.4% by mass or more, preferably 10% by mass or less, more preferably 7% by mass or less, still more preferably 5% by mass or less, particularly preferably 3% by mass or less, Most preferably, it is 1.5 mass% or less. In addition, when fluorinated cyclic carbonate is used as the non-aqueous solvent, the amount is 100% by volume in the non-aqueous solvent, preferably 1% by volume or more, more preferably 5% by volume or more, and still more preferably 10% by volume or more. Moreover, it is preferably 50% by volume or less, more preferably 35% by volume or less, and still more preferably 25% by volume or less.

  Further, as the fluorine-containing cyclic carbonate, a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter sometimes referred to as “fluorinated unsaturated cyclic carbonate”) may be used. If the fluorine number which a fluorinated unsaturated cyclic carbonate has is one or more, it will not restrict | limit in particular. The number of fluorines can be 6 or less, preferably 4 or less, and more preferably 1 or 2.

Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives, fluorinated ethylene carbonate derivatives substituted with an aromatic ring or a substituent having a carbon-carbon double bond.
Fluorinated vinylene carbonate derivatives include 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-5- And vinyl vinylene carbonate.

Examples of the fluorinated ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5. -Vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate 4,5-diflu B-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4- Examples thereof include phenylethylene carbonate.

  Among them, as the fluorinated unsaturated cyclic carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro -4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4 , 4-Difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4 Fluoro-4,5-diallyl carbonate, 4,5-difluoro-4,5-divinyl ethylene carbonate, 4,5-difluoro-4,5-diallyl carbonate is preferred because it forms a stable interface protective coating.

  The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited. The molecular weight is preferably 50 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the fluorinated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the fluorinated unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

A fluorinated unsaturated cyclic carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of the fluorinated unsaturated cyclic carbonate (the total amount in the case of two or more) is 100% by mass of the electrolytic solution, preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0. 0.1% by mass or more, particularly preferably 0.2% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less, and particularly preferably 3% by mass. It is as follows. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid the situation.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the fluorine-containing cyclic carbonate is 1:99 to 99: 1 from the viewpoint of composite interface protective film formation on the negative electrode. Preferably, 5:95 to 95: 5 is more preferable, 10:90 to 90:10 is still more preferable, 20:80 to 80:20 is particularly preferable, and 30:70 to 70:30 is extremely preferable. When it mix | blends in this range, the side reaction in the positive / negative electrode of each additive can be suppressed efficiently, and a battery characteristic improves. In particular, it is useful for improving the initial gas suppression effect and safety during overcharge.

1-2-2. Sulfur-containing organic compound The electrolytic solution of the present invention can further contain a sulfur-containing organic compound. The sulfur-containing organic compound is not particularly limited as long as it is an organic compound having at least one sulfur atom in the molecule, but is preferably an organic compound having an S═O group in the molecule, Sulfonated esters, cyclic sulfonates, chain sulfates, cyclic sulfates, chain sulfites and cyclic sulfites. However, those corresponding to fluorosulfonate are 1-2-2. It is not included in a sulfur-containing organic compound, but is included in a fluorosulfonate that is an electrolyte described later.

In the electrolytic solution of the present invention, by using the aromatic carboxylic acid ester represented by the formula (1) and the sulfur-containing organic compound in combination, the initial efficiency can be improved in a battery using this electrolytic solution. Thus, battery safety can be further improved by increasing the amount of overcharge gas.
Among these, a chain sulfonate ester, a cyclic sulfonate ester, a chain sulfate ester, a cyclic sulfate ester, a chain sulfite ester and a cyclic sulfite ester are preferable, and a compound having an S (═O) ₂ group is more preferable.

These esters may have a substituent. Here, the substituent is a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, preferably a carbon atom. , A group composed of one or more atoms selected from the group consisting of a hydrogen atom, an oxygen atom and a halogen atom, more preferably one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom and an oxygen atom It is a structured group. Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups or alkoxy groups; cyano groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; carboxy groups; An acyloxy group; an alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group. Of these, preferably a halogen atom; an alkoxy group; an unsubstituted or halogen-substituted alkyl group, alkenyl group or alkynyl group; an isocyanato group; a cyano group; an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group; More preferably a halogen atom, an unsubstituted alkyl group, or an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group or an acyloxy group, and more preferably a halogen atom, an unsubstituted alkyl group, or an alkoxycarbonyl group. Illustrative and preferred examples relating to these substituents apply to the substituents in the definition of A ¹² and A ¹³ in formula (2-2-1) and A ¹⁴ in formula (2-2-2) described later. .

More preferred are a chain sulfonate ester and a cyclic sulfonate ester. Among them, a chain sulfonate ester represented by the formula (2-2-1) and a cyclic sulfone represented by the formula (2-2-2) are preferred. Acid esters are preferred, and more preferred than cyclic sulfonate esters represented by formula (2-2-2).
1-2-2-1. A chain sulfonic acid ester represented by the formula (2-2-1)

(Where
A ¹² is an n ²¹ valent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent,
A ¹³ is a hydrocarbon group having 1 to 12 carbon atoms that may have a substituent,
n ²¹ is an integer of 1 to 4,
When n ²¹ is 2, A ¹² and A ¹³ may be the same or different. )
In Formula (2-2-1), A ¹² and A ¹³ are not combined to form a ring, and thus Formula (2-2-1) is a chain sulfonate.

n ²¹ is preferably an integer of 1 or more, 3 or less, more preferably an integer of 1 or more and 2 or less, and even more preferably 2.
As the n ²¹ valent hydrocarbon group having 1 to ¹² carbon atoms in A ¹² ,
Monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, alkynyl groups and aryl groups;
A divalent hydrocarbon group such as an alkylene group, an alkenylene group, an alkynylene group and an arylene group;
Trivalent hydrocarbon groups such as alkanetriyl groups, alkenetriyl groups, alkynetriyl groups and arenetriyl groups;
Tetravalent hydrocarbon groups such as alkanetetrayl group, alkenetetrayl group, alkynetetrayl group and arenetetrayl group;
Etc.

Of these, divalent hydrocarbon groups such as an alkylene group, alkenylene group, alkynylene group, and arylene group are preferable, and an alkylene group is more preferable. These correspond to the case where n ²¹ is 2.
Among the n ²¹ valent hydrocarbon groups having 1 to 12 carbon atoms, the monovalent hydrocarbon groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl. Group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2- A C1-C5 alkyl group such as dimethylpropyl group; vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group An alkenyl group having 2 to 5 carbon atoms such as 2-pentenyl group, 3-pentenyl group, 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl And an alkynyl group having 2 to 5 carbon atoms such as a group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group and the like.

  Examples of the divalent hydrocarbon group include an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group; a vinylene group, a 1-propenylene group, a 2-propenylene group, Alkenylene groups having 2 to 5 carbon atoms such as 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group; ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene And alkynylene groups having 2 to 5 carbon atoms such as 2-pentynylene group, preferably alkylene groups having 1 to 5 carbon atoms such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group. More preferably, carbon such as ethylene group, trimethylene group, tetramethylene group, pentamethylene group, etc. A number 2 to 5 of the alkylene group, more preferably a trimethylene group, a tetramethylene group, an alkylene group having 3 to 5 carbon atoms, such as pentamethylene group.

Examples of the trivalent and tetravalent hydrocarbon groups include trivalent and tetravalent hydrocarbon groups corresponding to the monovalent hydrocarbon group.
The n ²¹ valent hydrocarbon group having 1 to 12 carbon atoms having a substituent in A ¹² is a combination of the above substituent and the n ²¹ valent hydrocarbon group having 1 to 12 carbon atoms. Means group. A ¹² is preferably an n ²¹ valent hydrocarbon group having 1 to 5 carbon atoms and having no substituent.

The hydrocarbon group having 1 to 12 carbon atoms in A ¹³ is preferably a monovalent hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group and an aryl group, and more preferably an alkyl group.
Examples of the hydrocarbon group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n -C1-C5 alkyl groups such as pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group Preferably methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, more preferably methyl group, ethyl group, n-propyl group, still more preferably ethyl. Group, n-propyl group.

The hydrocarbon group having 1 to 12 carbon atoms and having a substituent in A ¹³ means a group in which the above substituent and the hydrocarbon group having 1 to 12 carbon atoms are combined. A ¹³ is preferably a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent, more preferably a hydrocarbon group having 1 to 5 carbon atoms having a substituent, More preferred is an alkyl group having an alkoxycarbonyl group as a substituent. Among them, methoxycarbonylmethyl group, ethoxycarbonylmethyl group, 1-methoxycarbonylethyl group, 1-ethoxycarbonylethyl group, 2-methoxycarbonylethyl group, 2-ethoxycarbonylethyl group, 1-methoxycarbonylpropyl group, 1-ethoxy A carbonylpropyl group, a 2-methoxycarbonylpropyl group, a 2-ethoxycarbonylpropyl group, a 3-methoxycarbonylpropyl group, and a 3-ethoxycarbonylpropyl group are preferable, and a 1-methoxycarbonylethyl group and a 1-ethoxycarbonylethyl group are more preferable. It is.

  The content of the chain sulfonate ester represented by the formula (2-2-1) (the total content in the case of two or more types) is 0.001% by mass or more in 100% by mass of the electrolytic solution. Preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.5% by mass or more, and 10% by mass or less. It is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and particularly preferably 1.5% by mass or less. Within this range, the high temperature storage characteristics are good.

  1-2-2-2. Cyclic sulfonic acid ester represented by formula (2-2-2)

(Where
A ¹⁴ is a divalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent. )
Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms in A ¹⁴ include an alkylene group, an alkenylene group, an alkynylene group, and an arylene group, preferably an alkylene group and an alkenylene group.

Examples of the divalent hydrocarbon group having 1 to 12 carbon atoms include alkylene groups having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group; a vinylene group and a 1-propenylene group. , 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group and the like, alkenylene group having 2 to 5 carbon atoms;
Examples thereof include alkynylene groups having 2 to 5 carbon atoms such as ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group.

  Of these, preferably an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group, a vinylene group, a 1-propenylene group, a 2-propenylene group, and a 1-butenylene group. C 2-5 alkenylene groups such as 2-butenylene group, 1-pentenylene group and 2-pentenylene group, more preferably alkylene having 3 to 5 carbon atoms such as trimethylene group, tetramethylene group and pentamethylene group. Group and 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group, etc., and alkenylene groups having 3 to 5 carbon atoms, more preferably trimethylene group, 1-propenylene group and 2-propenylene group.

Incidentally, the divalent hydrocarbon group having 1 to 12 carbon atoms which have a substituent in A ^14, a combination of divalent hydrocarbon group having 12 or less above substituents and the carbon atoms one or more groups Means that. A ¹⁴ is preferably a divalent hydrocarbon group having 1 to 5 carbon atoms and having no substituent.
A battery using the electrolytic solution of the present invention further containing a cyclic sulfonate ester represented by the formula (2-2-2) has improved initial efficiency and increased battery charge by increasing the amount of overcharge gas. This can be further improved. The content of the cyclic sulfonic acid ester represented by the formula (2-2-2) (in the case of two or more types, the total content) may be 0.001% by mass or more in 100% by mass of the electrolytic solution. Preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.4% by mass or more, and 10% by mass or less. It is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and particularly preferably 1.5% by mass or less.
Examples of the sulfur-containing organic compound include the following.

≪Chain sulfonate ester≫
Fluorosulfonic acid esters such as methyl fluorosulfonate and ethyl fluorosulfonate;
Methyl methanesulfonate, ethyl methanesulfonate, 2-propynyl methanesulfonate, 3-butynyl methanesulfonate, busulfan, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2- (Methanesulfonyloxy) propionate 2-propynyl, 2- (methanesulfonyloxy) propionate 3-butynyl, methanesulfonyloxyacetate methyl, methanesulfonyloxyacetate ethyl, methanesulfonyloxyacetate 2-propynyl and methanesulfonyloxyacetate 3- Methanesulfonic acid esters such as butynyl;
Methyl vinyl sulfonate, ethyl vinyl sulfonate, allyl vinyl sulfonate, propargyl vinyl sulfonate, methyl allyl sulfonate, ethyl allyl sulfonate, allyl sulfonate, propargyl allyl sulfonate and 1,2-bis (vinyl sulfonyloxy) ) Alkenyl sulfonic acid esters such as ethane;
Methanedisulfonic acid methoxycarbonylmethyl, methanedisulfonic acid ethoxycarbonylmethyl, methanedisulfonic acid 1-methoxycarbonylethyl, methanedisulfonic acid 1-ethoxycarbonylethyl, 1,2-ethanedisulfonic acid methoxycarbonylmethyl, 1,2-ethanedisulfonic acid Ethoxycarbonylmethyl, 1-methoxycarbonylethyl 1,2-ethanedisulfonate, 1-ethoxycarbonylethyl 1,2-ethanedisulfonate, methoxycarbonylmethyl 1,3-propanedisulfonate, ethoxycarbonyl 1,3-propanedisulfonate Methyl, 1,3-propanedisulfonic acid 1-methoxycarbonylethyl, 1,3-propanedisulfonic acid 1-ethoxycarbonylethyl, 1,3-butanedisulfonic acid methoxycarbonyl Methyl, 1,3-butane disulfonic acid ethoxycarbonylmethyl, 1,3-butane disulfonic acid 1-methoxycarbonyl-ethyl, alkyl disulfonic acid esters, such as 1,3-butane disulfonic acid 1-ethoxycarbonylethyl;

≪Cyclic sulfonate ester≫
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene -1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2 -Fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-propene -1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3 -Sultone compounds such as methyl-2-propene-1,3-sultone, 1,4-butane sultone and 1,5-pentane sultone;
Disulfonate compounds such as methylene methane disulfonate and ethylene methane disulfonate;
1,2,3-oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazol-2,2-dioxide 5H-1,2,3-oxathiazol-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 1,2,5-oxathiazolidine-2,2-dioxide, 1, 2,3-oxathiazinane-2,2-dioxide, 3-methyl-1,2,3-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine-2,2-dioxide and Nitrogen-containing compounds such as 1,2,4-oxathiazinane-2,2-dioxide.

  1,2,3-oxathiaphoslane-2,2-dioxide, 3-methyl-1,2,3-oxathiaphoslane-2,2-dioxide, 3-methyl-1,2,3-oxathi Aphoslane-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphoslane-2,2,3-trioxide, 1,2,4-oxathiaphoslane-2,2-dioxide 1,2,5-oxathiaphoslane-2,2-dioxide, 1,2,3-oxathiaphosphinan-2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan- 2,2-dioxide, 3-methyl-1,2,3-oxathiaphosphinan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosphinan-2,2,3- Trioxide, 1,2,4-oxathiaphosphie Down-dioxide, 1,2,5-oxathiazolium phosphinothricin Nan-2,2-dioxide and 1,2,6-oxa-thia phosphinothricin Nan -2,2-containing phosphorus compounds such as dioxide.

≪Chain sulfate ester≫
Dialkyl sulfate compounds such as dimethyl sulfate, ethyl methyl sulfate and diethyl sulfate.
≪Cyclic sulfate ester≫
1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, 1,3-butylene sulfate, 1,4-butylene sulfate, 1, Alkylene sulfate compounds such as 2-pentylene sulfate, 1,3-pentylene sulfate, 1,4-pentylene sulfate, and 1,5-pentylene sulfate.

≪Chainous sulfite ester≫
Dialkyl sulfite compounds such as dimethyl sulfite, ethyl methyl sulfite and diethyl sulfite.
≪Cyclic sulfite ester≫
1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, 1,2-butylene sulfite, 1,3-butylene sulfite, 1,4-butylene sulfite, 1, Alkylene sulfite compounds such as 2-pentylenesulfite, 1,3-pentylenesulfite, 1,4-pentylenesulfite and 1,5-pentylenesulfite.

  Of these, methyl 2- (methanesulfonyloxy) propionate, ethyl 2- (methanesulfonyloxy) propionate, 2-propynyl 2- (methanesulfonyloxy) propionate, 1-methoxycarbonylethyl propanedisulfonate, propanedisulfone 1-ethoxycarbonylethyl acid, 1-methoxycarbonylethyl butanedisulfonate, 1-ethoxycarbonylethyl butanedisulfonate, 1,3-propane sultone, 1-propene-1,3-sultone, 1,4-butane sultone, 1, 2-Ethylene sulfate, 1,2-ethylene sulfite, methyl methanesulfonate, and ethyl methanesulfonate are preferred from the viewpoint of improving the initial efficiency, and 1-methoxycarbonylethyl propanedisulfonate, 1-ethanepropanedisulfonate is preferable. Xicarbonylethyl, 1-methoxycarbonylethyl butanedisulfonate, 1-ethoxycarbonylethyl butanedisulfonate, 1,3-propane sultone, 1-propene-1,3-sultone, 1,2-ethylene sulfate, 1,2 -Ethylene sulfite is more preferable, and 1,3-propane sultone and 1-propene-1,3-sultone are more preferable.

A sulfur containing organic compound may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.
The content of the sulfur-containing organic compound (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably in 100% by mass of the electrolytic solution. It can be 0.1% by mass or more, particularly preferably 0.3% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 2% by mass. It is below mass%. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the sulfur-containing organic compound is such that the aromatic carboxylic acid ester represented by the formula (1): the sulfur-containing organic compound is 1:99 to 99: 1 is preferable, 5:95 to 95: 5 is more preferable, 10:90 to 90:10 is more preferable, 20:80 to 80:20 is particularly preferable, and 30:70 to 70:30 is extremely preferable. . If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-3. Phosphonic acid ester The electrolyte solution of the present invention may further contain a phosphonic acid ester. The phosphonic acid ester is not particularly limited as long as it is an organic compound having at least a phosphonic acid ester structure in the molecule.
In the electrolytic solution of the present invention, by using together the aromatic carboxylic acid ester represented by the formula (1) and the phosphonic acid ester, in the battery using this electrolytic solution, the initial rate characteristics can be improved while being stored. Later battery capacity can be improved.

The phosphonic acid ester may have a substituent. Here, the substituent is a group composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, preferably a carbon atom. , A group composed of one or more atoms selected from the group consisting of a hydrogen atom, an oxygen atom and a halogen atom. Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups or alkoxy groups; cyano groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; alkoxycarbonyl groups; Alkylsulfonyl group; alkoxysulfonyl group; dialkoxyphosphantriyl group; dialkoxyphosphoryl group and dialkoxyphosphoryloxy group. Among these, a halogen atom; an alkoxy group; an alkoxycarbonyloxy group; an acyl group; an alkoxycarbonyl group and an acyloxy group are preferable, a halogen atom and an alkoxycarbonyl group are more preferable, and an alkoxycarbonyl group is more preferable. is there. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an allyloxycarbonyl group, a propargyloxycarbonyl group, and the like, and preferably an ethoxycarbonyl group and a propargyloxycarbonyl group. The illustrations and preferred examples relating to these substituents are applied to the substituents in the definition of A ^{9 to} A ¹¹ in formula (2-3-1) described later.
Among these, a phosphonic acid ester represented by the formula (2-3-1) is preferable.

(Where
A ⁹ , A ¹⁰ and A ¹¹ are each independently an unsubstituted or halogen-substituted alkyl group having 1 to 5 carbon atoms, an alkenyl group or an alkynyl group,
n ³² is an integer of 0 to 6. )
Examples of the alkyl group, alkenyl group or alkynyl group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert- Alkyl groups such as butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group; vinyl Group, 1-propenyl group, 2-propenyl group (allyl group), isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, Alkenyl groups such as 4-pentenyl group; ethynyl group, 1-propynyl group, 2-propynyl group (propargyl group), 1-butynyl group, 2-butynyl Alkynyl groups such as 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group, 4-pentynyl group, methyl group, ethyl group, n-propyl group, n-butyl group, n -Pentyl group, vinyl group, 2-propenyl group (allyl group), 3-butenyl group, 4-pentenyl group, 2-propynyl group (propargyl group), 3-butynyl group and 4-pentynyl group are preferred, methyl group, An ethyl group, a 2-propenyl group (allyl group) and a 2-propynyl group (propargyl group) are more preferable, and a methyl group, an ethyl group and a 2-propynyl group (propargyl group) are still more preferable.
Examples of the phosphonic acid ester represented by the formula (2-3-1) include the following compounds.

<Compound with n ³² = 0 in Formula (2-3-1)>
Trimethyl phosphonoformate, methyl diethylphosphonoformate, methyl dipropylphosphonoformate, methyl dibutylphosphonoformate, triethyl phosphonoformate, ethyl dimethylphosphonoformate, ethyl dipropylphosphonoformate, ethyl Dibutyl phosphonoformate, tripropyl phosphonoformate, propyl dimethylphosphonoformate, propyl diethylphosphonoformate, propyl dibutylphosphonoformate, tributyl phosphonoformate, butyl dimethylphosphonoformate, butyl diethylphospho Noformate, butyl dipropylphosphonoformate, methyl bis (2,2,2-trifluoroethyl) phosphonoformate, ethyl bis (2 2,2-trifluoroethyl) phosphonoacetate formate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate formate and the like.

<Compound with n ³² = 1 in Formula (2-3-1)>
Trimethyl phosphonoacetate, methyl diethyl phosphonoacetate, methyl dipropyl phosphonoacetate, methyl dibutyl phosphonoacetate, triethyl phosphonoacetate, ethyl dimethylphosphonoacetate, ethyl diethyl phosphonoacetate, ethyl dipropylphosphonoacetate, ethyl dibutyl Phosphonoacetate, tripropyl phosphonoacetate, propyl dimethylphosphonoacetate, propyl diethylphosphonoacetate, propyl dibutylphosphonoacetate, tributyl phosphonoacetate, butyldimethylphosphonoacetate, butyldiethylphosphonoacetate, butyldipropylphosphono Acetate, methyl bis (2,2,2-trifluoroethyl) phosphonoacetate, ethyl bis (2 , 2,2-trifluoroethyl) phosphonoacetate, propyl bis (2,2,2-trifluoroethyl) phosphonoacetate, butyl bis (2,2,2-trifluoroethyl) phosphonoacetate, allyl dimethylphospho No acetate, allyl diethylphosphonoacetate, 2-propynyl dimethylphosphonoacetate, 2-propynyl diethylphosphonoacetate and the like.

<Compound with n ³² = 2 in Formula (2-3-1)>
Trimethyl 3-phosphonopropionate, methyl 3- (diethylphosphono) propionate, methyl 3- (dipropylphosphono) propionate, methyl 3- (dibutylphosphono) propionate, triethyl 3-phosphonopropionate, ethyl 3- (dimethylphosphono) propionate, ethyl 3- (dipropylphosphono) propionate, ethyl 3- (dibutylphosphono) propionate, tripropyl 3-phosphonopropionate, propyl 3- (dimethylphosphono) propionate, Propyl 3- (diethylphosphono) propionate, propyl 3- (dibutylphosphono) propionate, tributyl 3-phosphonopropionate, butyl 3- (dimethylphosphono) propionate, butyl 3- (diethylphosphono) prop Pionate, butyl 3- (dipropylphosphono) propionate, methyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, ethyl 3- (bis (2,2,2-trifluoroethyl) phosphono ) Propionate, propyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate, butyl 3- (bis (2,2,2-trifluoroethyl) phosphono) propionate and the like.

<Compound with n ³² = 3 in Formula (2-3-1)>
Trimethyl 4-phosphonobutyrate, methyl 4- (diethylphosphono) butyrate, methyl 4- (dipropylphosphono) butyrate, methyl 4- (dibutylphosphono)
Butyrate, triethyl 4-phosphonobutyrate, ethyl 4- (dimethylphosphono) butyrate, ethyl 4- (dipropylphosphono) butyrate, ethyl 4- (dibutylphosphono) butyrate, tripropyl 4-phosphonobutyrate, Propyl 4- (dimethylphosphono) butyrate, propyl 4- (diethylphosphono) butyrate, propyl 4- (dibutylphosphono) butyrate, tributyl 4-phosphonobutyrate, butyl 4- (dimethylphosphono) butyrate, butyl 4 -(Diethylphosphono) butyrate, butyl 4- (dipropylphosphono) butyrate and the like.

From the viewpoint of improving battery characteristics, compounds of n ³² = 0, 1, 2 are preferable, compounds of n ³² = 0, 1 are more preferable, compounds of n ³² = 1 are further preferable, and among compounds of n ³² = 1, compound a ⁹ to a ¹¹ is a saturated hydrocarbon group is preferred.
In particular, trimethyl phosphonoacetate, triethyl phosphonoacetate, 2-propynyl dimethylphosphonoacetate, and 2-propynyl diethylphosphonoacetate are preferable.

A phosphonic acid ester may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.
The content of phosphonic acid ester (total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0% in 100% by mass of the electrolytic solution. 0.1% by mass or more, more preferably 0.4% by mass or more, and 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less. Particularly preferably, it is 1% by mass or less, and most preferably 0.7% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) to the phosphonic acid ester is such that the aromatic carboxylic acid ester represented by the formula (1): phosphonic acid ester is 1:99 to 99: 1. It is preferable that 5:95 to 95: 5 is more preferable, 10:90 to 90:10 is more preferable, 20:80 to 80:20 is particularly preferable, and 30:70 to 70:30 is extremely preferable. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-4. Organic Compound Having Cyano Group The electrolytic solution of the present invention can contain an organic compound having a cyano group. The organic compound having a cyano group is not particularly limited as long as it is an organic compound having at least one cyano group in the molecule, but is preferably a formula (2-4-1) or a formula (2-4- 2) and a compound represented by formula (2-4-3), more preferably a compound represented by formula (2-4-1) and formula (2-4-2), and more preferably And a compound represented by formula (2-4-2). When the organic compound having a cyano group is also a cyclic compound having a plurality of ether bonds, it belongs to the cyclic compound having a plurality of ether bonds.
In the electrolytic solution of the present invention, by using together the aromatic carboxylic acid ester represented by the formula (1) and the organic compound having a cyano group, the initial charge / discharge efficiency is improved in a battery using this electrolytic solution. On the other hand, the charge / discharge efficiency after storage can be improved.

1-2-4-1. Compound represented by formula (2-4-1) A ¹ -CN (2-4-1)
(In the formula, A ¹ represents a hydrocarbon group having 2 to 20 carbon atoms.)
The molecular weight of the compound represented by the formula (2-4-1) is not particularly limited. The molecular weight is preferably 55 or more, more preferably 65 or more, still more preferably 80 or more,
Preferably it is 310 or less, More preferably, it is 185 or less, More preferably, it is 155 or less. If it is this range, it will be easy to ensure the solubility of the compound represented by Formula (2-4-1) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The method for producing the compound represented by the formula (2-4-1) is not particularly limited, and can be produced by arbitrarily selecting a known method.

  In the formula (2-4-1), examples of the hydrocarbon group having 2 to 20 carbon atoms include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and the like. An ethyl group, an n-propyl group, an iso-propyl group, and the like. Group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, n-pentyl group, tert-amyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group Group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group and other alkyl groups; vinyl group, 1-propenyl group, isopropenyl group, 1- Alkenyl groups such as butenyl and 1-pentenyl groups; ethynyl groups, 1-propynyl groups, 1-butynyl groups and 1-pentynyl groups Alkynyl groups such as groups; phenyl group, tolyl group, ethylphenyl group, n-propylphenyl group, i-propylphenyl group, n-butylphenyl group, sec-butylphenyl group, i-butylphenyl group, tert-butylphenyl Group, trifluoromethylphenyl group, xylyl group, benzyl group, phenethyl group, methoxyphenyl group, ethoxyphenyl group, aryl group such as trifluoromethoxyphenyl group, and the like are preferable.

Of these, a straight chain or branched alkyl group having 2 to 15 carbon atoms and an alkenyl group having 2 to 4 carbon atoms are more preferable from the viewpoint that the ratio of the cyano group to the whole molecule is large and the effect of improving battery characteristics is high. Further, a linear or branched alkyl group having 2 to 12 carbon atoms is more preferable, and a linear or branched alkyl group having 4 to 11 carbon atoms is particularly preferable.
Examples of the compound represented by the formula (2-4-1) include propionitrile, butyronitrile, pentanenitrile, hexanenitrile, heptanenitrile, octanenitrile, pelargononitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclopentanecarboro. Nitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitryl, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl -2-pentenenitrile, 2-hexenenitrile and the like.

Among these, pentanenitrile, octanenitrile, decanenitrile, dodecanenitrile and crotononitrile are preferable from the viewpoint of the stability of the compound, battery characteristics and production, pentanenitrile, decanenitrile, dodecanenitrile and crotononitrile are more preferable, Pentanenitrile, decanenitrile and crotononitrile are preferred.
As the compound represented by the formula (2-4-1), one type may be used alone, or two or more types may be used in any combination and ratio. The amount of the compound represented by the formula (2-4-1) (the total amount in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the non-aqueous electrolyte solution, preferably It can be 0.01% by mass or more, more preferably 0.1% by mass or more, and 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass. Hereinafter, it is particularly preferably 1% by mass or less, and most preferably 0.5% by mass or less. Within the above range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

1-2-4-2. Compound represented by formula (2-4-2) NC-A ² -CN (2-4-2)
(Where
A ² is an organic group having 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom. . )
The organic group having 1 to 10 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom is a carbon atom and In addition to an organic group composed of a hydrogen atom, an organic group that may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, or a halogen atom is included. In the organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom, a part of the skeleton carbon atom in the group composed of the carbon atom and the hydrogen atom is substituted with these atoms. Or an organic group having a substituent composed of these atoms.

  The molecular weight of the compound represented by the formula (2-4-2) is not particularly limited. The molecular weight is preferably 65 or more, more preferably 80 or more, still more preferably 90 or more, preferably 270 or less, more preferably 160 or less, and still more preferably 135 or less. If it is this range, it will be easy to ensure the solubility of the compound represented by Formula (2-4-2) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The method for producing the compound represented by the formula (2-4-2) is not particularly limited, and can be produced by arbitrarily selecting a known method.

As A ² in the compound represented by the formula (2-4-2), an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, a cycloalkenylene group or a derivative thereof , Arylene group or derivative thereof, carbonyl group or derivative thereof, sulfonyl group or derivative thereof, sulfinyl group or derivative thereof, phosphonyl group or derivative thereof, phosphinyl group or derivative thereof, amide group or derivative thereof, imide group or derivative thereof, ether Groups or derivatives thereof, thioether groups or derivatives thereof, borinic acid groups or derivatives thereof, borane groups or derivatives thereof, and the like.

Among these, from the viewpoint of improving battery characteristics, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, an arylene group or a derivative thereof is preferable. A ² is more preferably an alkylene group having 2 to 5 carbon atoms which may have a substituent.
Examples of the compound represented by the formula (2-4-2) include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile. Nitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,3,3-trimethylsuccinonitrile, 2,2, 3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile , Bicyclohexyl-2 2-dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2 -Diisobutyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, maleonitrile, fumaronitrile, 1,4 -Dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodeca 1,2-didianobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′-(ethylenedithio) dipropionitrile, and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like can be mentioned.

  Of these, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10 -Tetraoxaspiro [5,5] undecane and fumaronitrile are preferred from the viewpoint of improving storage characteristics. Furthermore, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, glutaronitrile and 3,9-bis (2-cyanoethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane are The effect of improving the storage characteristics is particularly excellent, and the deterioration due to the side reaction at the electrode is small, which is more preferable. Usually, in dinitrile compounds, the smaller the molecular weight, the larger the proportion of cyano groups in one molecule and the higher the viscosity of the molecule, while the higher the molecular weight, the higher the boiling point of the compound. Therefore, succinosuccinonitrile, glutaronitrile, adiponitrile, and pimelonitrile are more preferable from the viewpoint of improving working efficiency.

As the compound represented by the formula (2-4-2), one type may be used alone, or two or more types may be used in any combination and ratio. The amount of the compound represented by the formula (2-4-2) (the total amount in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the electrolytic solution, and preferably is 0.00. 01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass. It is contained at a concentration of not more than mass%. When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.
1-2-4-3. Compound represented by formula (2-4-3)

(Where
A ³ is an organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of hydrogen atom, carbon atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom and halogen atom. , N ⁴³ is an integer of 0 or more and 5 or less. )
An organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom is a carbon atom. And an organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom in addition to an organic group composed of a hydrogen atom. In the organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom or a halogen atom, a part of the skeleton carbon atom in the group composed of the carbon atom and the hydrogen atom is substituted with these atoms. Or an organic group having a substituent composed of these atoms.

The n ⁴³ is an integer of 0 or more and 5 or less, preferably 0 or more and 3 or less, more preferably 0 or more and 1 or less, and particularly preferably 0.
In addition, A ³ is preferably an organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, and a sulfur atom. More preferably, it is an organic group having 1 to 12 carbon atoms composed of one or more atoms selected from the group consisting of a hydrogen atom, a carbon atom and an oxygen atom, and may have a substituent. It is more preferably an aliphatic hydrocarbon group having a number of 1 or more and 12 or less.

Here, the substituent represents a group composed of one or more atoms selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom, sulfur atom, phosphorus atom and halogen atom.
Substituents include halogen atoms; unsubstituted or halogen-substituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups, alkoxy groups; isocyanato groups; alkoxycarbonyloxy groups; acyl groups; carboxyl groups; alkoxycarbonyl groups; An alkylsulfonyl group; an alkoxysulfonyl group; a dialkoxyphosphantriyl group; a dialkoxyphosphoryl group and a dialkoxyphosphoryloxy group, preferably a halogen atom; an alkoxy group or an unsubstituted or halogen-substituted alkyl group; More preferably a halogen atom or an unsubstituted or halogen-substituted alkyl group, and still more preferably an unsubstituted alkyl group.

The aliphatic hydrocarbon group is not particularly limited, but may have 1 or more carbon atoms, preferably 2 or more, more preferably 3 or more, and 12 or less, preferably 8 Below, more preferably 6 or less.
Examples of the aliphatic hydrocarbon group, in response to n ^43, alkanetriyl, alkanetetrayl groups, alkane pen tile group, alkanetetrayl groups, alkene tri-yl group, alkene tetrayl group, alkene pen tile group, alkene Examples thereof include a tetrayl group, an alkyne triyl group, an alkyne tetrayl group, an alkyne pentile group, and an alkyne tetrayl group.

Of these, saturated hydrocarbon groups such as alkanetriyl groups, alkanetetrayl groups, alkanepentyl groups, and alkanetetrayl groups are more preferable, and alkanetriyl groups are more preferable.
Furthermore, the compound represented by the formula (2-4-3) is more preferably a compound represented by the formula (2-4-3 ′).

(Wherein, ^{A 4} and ^{A 5} are as defined in the above ^{A 3.)}
The above A ⁴ and A ⁵ are more preferably a hydrocarbon group having 1 to 5 carbon atoms which may have a substituent.
As the hydrocarbon group, methylene group, ethylene group, trimethylene group, tetraethylene group, pentamethylene group, vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group 2-pentenylene group, ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group, 2-pentynylene group, and the like.

Among these, a methylene group, an ethylene group, a trimethylene group, a tetraethylene group, and a pentamethylene group are preferable, and a methylene group, an ethylene group, and a trimethylene group are more preferable.
A ⁴ and A ⁵ are preferably not the same as each other but different.
The molecular weight of the compound represented by the formula (2-4-3) is not particularly limited. The molecular weight is preferably 90 or more, more preferably 120 or more, further preferably 150 or more, preferably 450 or less, more preferably 300 or less, and further preferably 250 or less. If it is this range, it will be easy to ensure the solubility of the compound represented by Formula (2-4-3) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The method for producing the compound represented by the formula (2-4-3) is not particularly limited, and can be produced by arbitrarily selecting a known method.
Examples of the compound represented by the formula (2-4-3) include the following compounds.

  Of these,

Is preferable from the viewpoint of improving the storage characteristics.
The organic compound which has a cyano group may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.
The amount of the compound represented by the formula (2-4-3) (the total amount in the case of 2 or more types) can be 0.001% by mass or more in 100% by mass of the electrolytic solution, and preferably is 0.00. 01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass. It is contained at a concentration of not more than mass%, particularly preferably not more than 2 mass%. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the organic compound having a cyano group is such that the aromatic carboxylic acid ester represented by the formula (1): the organic compound having a cyano group is 1: It is preferably 99 to 99: 1, more preferably 5:95 to 95: 5, still more preferably 10:90 to 90:10, particularly preferably 20:80 to 80:20, and 30:70 to 70: 30 is very preferred. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-5. The organic compound which has an isocyanate group The electrolyte solution of this invention can contain the organic compound which has an isocyanate group. The organic compound having an isocyanate group is not particularly limited as long as it is an organic compound having at least one isocyanate group in the molecule, but the number of isocyanate groups is preferably 1 or more and 4 or less, more preferably 2 in one molecule. Above 3 or less, more preferably 2.

In the electrolytic solution of the present invention, by using together the aromatic carboxylic acid ester represented by the formula (1) and the compound having an isocyanate group, generation of initial gas can be suppressed in a battery using this electrolytic solution. Thus, the battery capacity after storage can be improved.
The organic compound having an isocyanate group is preferably a linear or branched alkylene group, a cycloalkylene group, a structure in which a cycloalkylene group and an alkylene group are linked, an aromatic hydrocarbon group, an aromatic hydrocarbon group and an alkylene group. , Ether structure (—O—), ether structure (—O—) and alkylene group linked structure, carbonyl group (—C (═O) —), carbonyl group and alkylene group linked structure , A sulfonyl group (—S (═O) —), a structure in which a sulfonyl group and an alkylene group are linked, or a compound having a structure in which these are halogenated, and the like. Chain or branched alkylene group, cycloalkylene group, structure in which cycloalkylene group and alkylene group are linked, aromatic hydrocarbon Or an aromatic hydrocarbon group and an isocyanate group in a structure in which alkylene groups are linked a compound bound, more preferably a compound that the isocyanate group is bonded to a structure in which a cycloalkylene group and an alkylene group are linked. The molecular weight of the organic compound having an isocyanate group is not particularly limited. The molecular weight is preferably 80 or more, more preferably 115 or more, still more preferably 170 or more, and 300 or less, more preferably 230 or less. If it is this range, it will be easy to ensure the solubility of the organic compound which has an isocyanate group with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the organic compound having an isocyanate group is not particularly limited, and can be produced by arbitrarily selecting a known method. Moreover, you may use a commercial item.

Examples of the organic compound having an isocyanate group include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, tertiary butyl isocyanate, pentyl isocyanate hexyl isocyanate, cyclohexyl isocyanate, vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, propargyl isocyanate, phenyl. Organic compounds having one isocyanate group such as isocyanate and fluorophenyl isocyanate;
Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-diisocyanate Natopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5 -Diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanato) Methyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1 ′ -Diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-
4,4′-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (
Methyl isocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methyl isocyanate), isophorone diisocyanate, carbonyl diisocyanate, 1,4-diisocyanatobutane-1,4-dione, 1,5- Organic compounds having two isocyanate groups such as diisocyanatopentane-1,5-dione, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate;
Etc.

Among these, monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1]
Heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2 Organic compounds having two isocyanate groups, such as 1,4,4-trimethylhexamethylene diisocyanate, are preferable from the viewpoint of improving storage characteristics, and hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4 , 4'-diisocyanate, bicyclo [
2.2.1] Heptane-2,5-diylbis (methylisocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate), isophorone diisocyanate, 2,2,4-trimethylhexa Methylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate are more preferred, and 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1 More preferred are heptane-2,5-diylbis (methylisocyanate) and bicyclo [2.2.1] heptane-2,6-diylbis (methylisocyanate).

  The organic compound having an isocyanate group may be a trimer compound derived from a compound having at least two isocyanate groups in the molecule, or an aliphatic polyisocyanate obtained by adding a polyhydric alcohol thereto. Examples thereof include biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of formulas (2-5-1) to (2-5-4).

(In the formula, R ^{51 to} R ⁵⁴ and R ⁵⁴ ′ are independently a divalent hydrocarbon group (for example, a tetramethylene group or a hexamethylene group), and R ⁵³ ′ is independently a trivalent group. Hydrocarbon group.)
Organic compounds having at least two isocyanate groups in the molecule also include so-called blocked isocyanates that are blocked with a blocking agent to enhance storage stability. Examples of the blocking agent include alcohols, phenols, organic amines, oximes, and lactams. Specific examples include n-butanol, phenol, tributylamine, diethylethanolamine, methyl ethyl ketoxime, and ε-caprolactam. Etc.

For the purpose of promoting a reaction based on an organic compound having an isocyanate group and obtaining a higher effect, a metal catalyst such as dibutyltin dilaurate or the like, 1,8-diazabicyclo [5.4
. 0] It is also preferable to use an amine catalyst such as undecene-7 in combination.
The organic compound which has an isocyanate group may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.

The amount of the organic compound having an isocyanate group (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.1% by mass or more, more preferably in 100% by mass of the electrolytic solution. Is 0.3% by mass or more and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the organic compound having an isocyanate group is such that the aromatic carboxylic acid ester represented by the formula (1): the organic compound having an isocyanate group is 1: It is preferably 99 to 99: 1, more preferably 5:95 to 95: 5, still more preferably 10:90 to 90:10, particularly preferably 20:80 to 80:20, and 30:70 to 70: 30 is very preferred. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-6. Silicon-containing compound The electrolytic solution of the present invention may contain a silicon-containing compound. The silicon-containing compound is not particularly limited as long as it is a compound having at least one silicon atom in the molecule. In the electrolytic solution of the present invention, the combined use of the aromatic carboxylic acid ester picture represented by the formula (1) and the silicon-containing compound improves the initial high-rate discharge capacity while improving the capacity after storage. it can.
As the silicon-containing compound, a compound represented by the formula (2-6) is preferable.

(Where
R ⁶¹ , R ⁶² and R ⁶³ are each independently a hydrogen atom, a halogen atom or a hydrocarbon group having 10 or less carbon atoms,
X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a silicon atom. )
For the hydrocarbon group, the examples and preferred examples of the hydrocarbon group in the formula (I) are applied. R ⁶¹ , R ⁶² and R ⁶³ are preferably hydrogen atom, fluorine atom, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert. -A butyl group and a phenyl group, more preferably a methyl group.

X ⁶¹ is an organic group containing at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom and a silicon atom, and preferably an organic group containing at least an oxygen atom or a silicon atom. Here, the organic group refers to a group composed of one or more atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, silicon atoms, sulfur atoms, phosphorus atoms and halogen atoms. Represent. Examples of the organic group include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, a CN group, an isocyanato group, a fluoro group, an alkylsulfonic acid group, and a trialkylsilyl group. A part of the monovalent organic group may be substituted with a halogen atom. The carbon number of the organic group can be 1 or more, preferably 3 or more, more preferably 5 or more, and 15 or less, preferably 12 or less, more preferably 8 or less. It is.

Of these, alkylsulfonic acid groups, trialkylsilyl groups, boric acid groups, phosphoric acid groups and phosphorous acid groups are preferred.
Examples of the silicon-containing compound include the following compounds.
Tris borate (trimethylsilyl), tris borate (trimethoxysilyl), tris borate (triethylsilyl), tris borate (triethoxysilyl), tris borate (dimethylvinylsilyl) and tris borate (diethylvinylsilyl) Boric acid compounds such as: Tris phosphate (trimethylsilyl), Tris phosphate (triethylsilyl), Tris phosphate (tripropylsilyl), Tris phosphate (triphenylsilyl), Tris phosphate (trimethoxysilyl), Phosphoric acid Phosphoric acid compounds such as tris (triethoxysilyl), tris (triphenoxysilyl) phosphate, tris (dimethylvinylsilyl) phosphate and tris (diethylvinylsilyl) phosphate;
Tris phosphite (trimethylsilyl), Tris phosphite (triethylsilyl), Tris phosphite (tripropylsilyl), Tris phosphite (triphenylsilyl), Tris phosphite (trimethoxysilyl), Phosphorous acid Phosphite compounds such as tris (triethoxysilyl), tris phosphite (triphenoxysilyl), tris phosphite (dimethylvinylsilyl) and tris phosphite (diethylvinylsilyl);
Sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate;
Hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, 1,1,2,2-tetraethyldisilane, 1,2-diphenyltetramethyldisilane and 1,1,2,2-tetraphenyl Disilane compounds such as disilane;
Etc.

  Of these, tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite, trimethylsilyl methanesulfonate, trimethylsilyl tetrafluoromethanesulfonate, hexamethyldisilane, hexaethyldisilane, 1,2- Diphenyltetramethyldisilane and 1,1,2,2-tetraphenyldisilane are preferred, and tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite and hexamethyldisilane are more preferred.

In addition, these silicon containing compounds may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The silicon-containing compound (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass in 100% by mass of the electrolytic solution. % Or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the silicon-containing compound (the total amount in the case of two or more) is the aromatic carboxylic acid ester represented by the formula (1): the silicon-containing compound. Is preferably 1:99 to 99: 1, more preferably 5:95 to 95: 5, still more preferably 10:90 to 90:10, particularly preferably 20:80 to 80:20, and 30: 70-70: 30 is very preferable. If it is this range, a battery characteristic, especially an initial stage characteristic can be improved significantly. Although this principle is not clear, it is considered that the side reaction of the additive on the electrode can be minimized by mixing at this ratio.

1-2-7. Aromatic compounds other than formula (1) The electrolyte solution of the present invention may contain an aromatic compound other than formula (1). The aromatic compound other than the formula (1) is not particularly limited as long as it is an organic compound other than the formula (2) having at least one aromatic ring in the molecule, but preferably the formula (2-7- 1) and formula (2-7-2)
).

(In the formula, the substituent X ⁷¹ represents a halogen atom, a halogen atom or an organic group which may have a hetero atom. The organic group which may have a hetero atom is a group having 1 to 12 carbon atoms. A linear, branched or cyclic saturated hydrocarbon group, a group having a carboxylic ester structure, a group having a carbonate structure, a group having a phosphorus atom, a group having a sulfur atom, and a group having a silicon atom are shown. substituents may further halogen atom, a hydrocarbon group, an aromatic group, a halogen-containing hydrocarbon group may be substituted with a halogen-containing aromatic group. the number n ⁷¹ of the substituents X ⁷¹ 1 to 6 In the case of having a plurality of substituents, each substituent may be the same or different, and may form a ring.)
Among these, a linear, branched or cyclic saturated hydrocarbon group having 1 to 12 carbon atoms, a group having a carboxylic acid ester structure, and a group having a carbonate structure are preferable from the viewpoint of battery characteristics. More preferably, it is a group having a straight chain, branched chain or cyclic saturated hydrocarbon group having 3 to 12 carbon atoms and a carboxylate structure.

The number n ⁷¹ of the substituents X ⁷¹ is preferably 1 or more 5 or less, more preferably 1 to 3, still more preferably 1 to 2, particularly preferably 1.
X ⁷¹ represents a halogen atom, a halogen atom or an organic group which may have a hetero atom.
Examples of the halogen atom include chlorine, fluorine and the like, preferably fluorine.

  Examples of the organic group having no hetero atom include linear, branched, and cyclic saturated hydrocarbon groups having 3 to 12 carbon atoms. The linear and branched groups include those having a ring structure. It is. Specific examples of linear, branched, and cyclic saturated hydrocarbon groups having 1 to 12 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and pentyl. Group, tert-pentyl group, cyclopentyl group, cyclohexyl group, butylcyclohexyl group, and the like. The number of carbon atoms is preferably 3 or more and 12 or less, more preferably 3 or more and 10 or less, still more preferably 3 or more and 8 or less, still more preferably 3 or more and 6 or less, and most preferably 3 or more and 5 or less.

  Examples of the hetero atom constituting the organic group having a hetero atom include an oxygen atom, a sulfur atom, a phosphorus atom, and a silicon atom. Examples of the group having an oxygen atom include a group having a carboxylic ester structure and a group having a carbonate structure. Examples of those having a sulfur atom include groups having a sulfonate structure. Examples of those having a phosphorus atom include a group having a phosphate ester structure, a group having a phosphonate ester structure, and the like. Examples of the group having a silicon atom include a group having a silicon-carbon structure.

Examples of the aromatic compound represented by the formula (2-7-1) include the following.
As ^X71 being a halogen atom or an organic group which may have a halogen atom, chlorobenzene, fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, benzotrifluoride, etc. And preferred are fluorobenzene and hexafluorobenzene. More preferred is fluorobenzene.

As ^X71 is a hydrocarbon group having 1 to 12 carbon atoms,
2,2-diphenylpropane, 1,4-diphenylcyclohexane, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4- Phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, propylbenzene, butylbenzene, tert-butylbenzene, tert-amylbenzene, and the like, preferably 2,2-diphenylpropane, 1,4-diphenylcyclohexane, Cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexa , Trans-1-butyl-4-phenylcyclohexane, toluene, ethylbenzene, propylbenzene, butylbenzene, tert-butylbenzene, tert-amylbenzene, more preferably 2,2-diphenylpropane, cyclopentylbenzene, cyclohexylbenzene, 1,1-diphenylcyclohexane, tert-butylbenzene, and tert-amylbenzene are preferable, and cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene are more preferable.

As ^X71 is a group having a carboxylate structure,
Phenyl acetate, benzyl acetate, 2-phenylethyl acetate, 3-phenylpropyl acetate, 4-phenylbutyl acetate, phenyl propionate, benzyl propionate, 2-phenylethyl propionate, 3-phenylpropyl propionate, 4-propionate 4- Phenylbutyl, phenyl butyrate, benzyl butyrate, 2-phenylethyl butyrate, 3-phenylpropyl butyrate, 4-phenylbutyl butyrate, phenethyl phenylacetate, 2,2-bis (4-acetoxyphenyl) propane, and the like are preferable. 2-phenylethyl acetate, 3-phenylpropyl acetate, 2-phenylethyl propionate, 3-phenylpropyl propionate, 2,2-bis (4-acetoxyphenyl) propane, more preferably 2-phenylethyl acetate, 3-phenyl acetate It is a pill.

As X ⁷¹ is a group having a carbonate structure,
2,2-bis (4-methoxycarbonyloxyphenyl) propane, 1,1-bis (4-methoxycarbonyloxyphenyl) cyclohexane, diphenyl carbonate, methylphenyl carbonate, ethylphenyl carbonate, 2-tert-butylphenylmethyl carbonate, 2-tert-butylphenylethyl carbonate, bis (2-tert-butylphenyl) carbonate, 4-tert-butylphenylmethyl carbonate, 4-tert-butylphenylethyl carbonate, bis (4-tert-butylphenyl) carbonate, benzyl Examples include methyl carbonate, benzyl ethyl carbonate, dibenzyl carbonate, and the like, preferably 2,2-bis (4-methoxycarbonyloxyphenyl) propane, , 1,1-bis (4-methoxycarbonyloxyphenyl) cyclohexane body, diphenyl carbonate, methyl phenyl carbonate, more preferably diphenyl carbonate, methyl phenyl carbonate, more preferably methyl phenyl carbonate.

As ^X71 is a group having a sulfonate structure,
Examples include methyl phenyl sulfonate, ethyl phenyl sulfonate, diphenyl sulfonate, phenyl methyl sulfonate, 2-tert-butylphenyl methyl sulfonate, 4-tert-butylphenyl methyl sulfonate, cyclohexyl phenyl methyl sulfonate, and the like, preferably methyl phenyl sulfonate, diphenyl sulfonate 2-tert-butylphenylmethylsulfonate, 4-tert-butylphenylmethylsulfonate, cyclohexylphenylmethylsulfonate, more preferably methylphenylsulfonate, 2-tert-butylphenylmethylsulfonate, 4-tert-butylphenylmethylsulfonate Cyclohexyl phenyl methyl sulfonate.

As ^X71 is a group having a silicon-carbon structure,
Examples include trimethylphenylsilane, diphenylsilane, diphenyltetramethyldisilane, and the like, preferably trimethylphenylsilane.
As ^X71 is a group having a phosphate structure,
Triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylphenyl) phosphate, tris (4-tert-butylphenyl) phosphate, tris (2-tert-amylphenyl) phosphate, tris ( 3-tert-amylphenyl) phosphate, tris (4-tert-amylphenyl) phosphate, tris (2-cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, diethyl (4 -Methylbenzyl) phosphonate and the like, preferably triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylpheny). ) Phosphate, tris (4-tert-butylphenyl) phosphate, tris (2-tert-amylphenyl) phosphate, tris (3-tert-amylphenyl) phosphate, tris (4-tert-amylphenyl) phosphate, tris (2 -Cyclohexylphenyl) phosphate, tris (3-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, more preferably tris (2-tert-butylphenyl) phosphate, tris (4-tert-butylphenyl) Phosphate, tris (2-cyclohexylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate.

As X ⁷¹ is a group having a phosphonic acid ester structure,
Dimethylphenylphosphonate, diethylphenylphosphonate, methylphenylphenylphosphonate, ethylphenylphenylphosphonate, diphenylphenylphosphonate, dimethyl- (4-fluorophenyl) -phosphonate, dimethylbenzylphosphonate, diethylbenzylphosphonate, methylphenylbenzylphosphonate, ethylphenylbenzylphosphonate , Diphenylbenzylphosphonate, dimethyl- (4-fluorobenzyl) phosphonate, diethyl- (4-fluorobenzyl) phosphonate and the like, preferably dimethylphenylphosphonate, diethylphenylphosphonate, dimethyl- (4-fluorophenyl) phosphonate, Dimethyl benzyl phosphonate, diethyl benzyl phosphonate, di Til- (4-fluorobenzyl) phosphonate, diethyl- (4-fluorobenzyl) phosphonate, more preferably dimethylphenylphosphonate, diethylphenylphosphonate, dimethylbenzylphosphonate, diethylbenzylphosphonate, dimethyl- (4-fluorobenzyl) phosphonate , Diethyl- (4-fluorobenzyl) phosphonate.

The aromatic compound represented by the formula (2-7-1) includes a fluorinated product of the aromatic compound. Specifically, a portion having a hydrocarbon group such as trifluoromethylbenzene, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, trifluoromethylbenzene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, etc. Fluorinated product: partially fluorinated product having a carboxylic acid ester structure such as 2-fluorophenyl acetate and 4-fluorophenyl acetate; trifluoromethoxybenzene, 2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,4 -Partially fluorinated compounds having an ether structure such as difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole, 4-trifluoromethoxyanisole And preferably a partially fluorinated compound having a hydrocarbon group such as trifluoromethylbenzene, 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; 2 -Partially fluorinated compounds having a carboxylate structure such as fluorophenylacetate and 4-fluorophenylacetate; trifluoromethoxybenzene 2-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, 4-trifluoromethoxyanisole Partially fluorinated products having an ether structure such as 2-fluorotoluene, 3-fluorotoluene, 4-fluorotoluene, etc., and more preferably partially fluorinated products having a hydrocarbon group Partially fluorinated compounds having a carboxylic acid ester structure such as 2-fluorophenyl acetate and 4-fluorophenyl acetate; trifluoromethoxybenzene, 2-fluoroanisole, 4-fluoroanisole, 2,4-difluoroanisole, 4-trifluoro Partially fluorinated compounds having an ether structure such as methoxyanisole.

  The aromatic compound represented by the formula (2-7-1) may be used alone or in combination of two or more in any combination and ratio. The amount of the aromatic compound represented by the formula (2-7-1) (the total amount in the case of two or more types) can be 0.001% by mass or more in 100% by mass of the electrolytic solution, preferably 0.01 mass% or more, more preferably 0.1 mass% or more, still more preferably 0.4 mass% or more, and can be 10 mass% or less, preferably 8 mass% or less, more preferably Is 5% by mass or less, more preferably 4% by mass or less, and particularly preferably 4% by mass or less. By being in the said range, the effect of this invention is easy to express and it is easy to prevent the increase in resistance of a battery.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the aromatic compound represented by the formula (2-7-1) (the total amount in the case of two or more) is 1:99 to 99. : 1 is preferable, 10:90 to 90:10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, overcharge characteristics can be improved without deterioration of battery characteristics.

(Wherein R ^{11 to} R ¹⁵ are each independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, and R ¹⁶ and R ¹⁷ are independently carbon atoms. It is a hydrocarbon group having a number of 1 or more and 12 or less, and at least two of R ^{11 to} R ¹⁷ may be combined to form a ring, provided that the formula (2-7-2) is (A) And (B):
(A) At least one of R ^{11 to} R ¹⁵ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
(B) The total number of carbon atoms of R ^{11 to} R ¹⁷ is 3 or more and 20 or less, satisfying at least one condition)
It is an aromatic compound represented by these. If at least two of R ¹¹ to R ¹⁷ but that together form a ^ring, it is preferred that two of R 11 ^{to R 17} form a ring together.

R ¹⁶ and R ¹⁷ are each independently a hydrocarbon group having 1 to 12 carbon atoms (for example, an alkyl group or an aryl group), and R ¹⁶ and R ¹⁷ are combined to form a ring (for example, a hydrocarbon group). A cyclic group) may be formed. From the viewpoint of improving the initial efficiency, solubility and storage characteristics, R ¹⁶ and R ¹⁷ are preferably hydrocarbon groups having 1 to 12 carbon atoms, or hydrocarbons formed by combining R ¹⁶ and R ¹⁷ together. A cyclic group, more preferably a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, or a hydrocarbon group formed by combining R ¹⁶ and R ¹⁷ together 5 -8-membered cyclic group, more preferably a methyl group, an ethyl group, a cyclohexyl group formed by combining R ¹⁶ and R ¹⁷ and a cyclopentyl group, and most preferably a methyl group, an ethyl group, R A cyclohexyl group formed by combining ¹⁶ and R ¹⁷ together.

R ^{11 to} R ¹⁵ are independently hydrogen, halogen, or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group, an aryl group, and an aralkyl group). They may be joined together to form a ring (for example, a cyclic group which is a hydrocarbon group). From the viewpoint of improving initial efficiency, solubility and storage characteristics, hydrogen, fluorine, unsubstituted or halogen-substituted hydrocarbon group having 1 to 12 carbon atoms is preferable, and hydrogen, fluorine, unsubstituted or fluorine-substituted is more preferable. A hydrocarbon group having 1 to 10 carbon atoms, more preferably hydrogen, fluorine, tert-butyl group, tert-pentyl group, tert-hexyl group, tert-heptyl group, methyl group, ethyl group, propyl group, Butyl group, trifluoromethyl group, nonafluoro tert-butyl group, 1-methyl-1-phenyl-ethyl group, 1-ethyl-1-phenyl-propyl group, particularly preferably hydrogen, fluorine, tert-butyl group, 1-methyl-1-phenyl-ethyl group, most preferably hydrogen, tert-butyl group, 1-methyl-1- Eniru - an ethyl group.

Any one of R ^{11 to} R ¹⁵ may be combined with R ¹⁶ to form a ring (for example, a cyclic group that is a hydrocarbon group). Preferably, R ¹¹ and R ¹⁶ are combined to form a ring (for example, a cyclic group that is a hydrocarbon group). In this case, R ¹⁷ is preferably an alkyl group. Examples of compounds in which R ¹⁷ is a methyl group and R ¹¹ and R ¹⁶ are combined to form a ring include 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl-1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane and the like.

Formula (2-7-2) is represented by (A) and (B):
(A) At least one of R ^{11 to} R ¹⁵ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms.
(B) The total number of carbon atoms of R ^{11 to} R ¹⁷ is 3 or more and 20 or less.
Satisfies at least one of the conditions.

Formula (2-7-2) preferably satisfies (A) from the viewpoint of suppressing oxidation on the positive electrode within the normal battery operating voltage range, and from the viewpoint of solubility in the electrolyte, B) is preferably satisfied. Formula (2-7-2) may satisfy both (A) and (B).
Regarding (A), if at least one of R ^{11 to} R ¹⁵ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, a ring is formed even if the other is a hydrogen atom You may do it. From the viewpoint of solubility in the electrolytic solution, the carbon number of the unsubstituted or halogen-substituted hydrocarbon group is preferably 1 or more and 10 or less, more preferably 1 or more and 5 or less, still more preferably 1 or more and 3 or less, and still more preferably. 1 or 2, most preferably 1.

For ^(B), the total number of carbon atoms of R 11 ^{to R 17} is as long as 3 to ^{20, R 11} ~
At least two of R ¹⁷ may be joined together to form a ring. When at least two of R ^{11 to} R ¹⁷ are combined to form a ring, in calculating the total number of carbon atoms, carbon that does not correspond to R ^{11 to} R ¹⁷ among the carbons forming the ring (R for ¹¹ to R ^15, carbon atoms constituting the benzene ring to which they are ^attached, for ^{R 16} and ^{R 17,} carbon atoms in the benzyl position) is set to be not counted. The total number of carbon atoms is preferably 3 or more and 14 or less, more preferably 3 or more and 10 or less, from the viewpoint of solubility in the electrolytic solution. For example, compounds in which R ¹⁷ is a methyl group and R ¹¹ and R ¹⁶ are combined to form a ring include 1-phenyl-1,3,3-trimethylindane, 2,3-dihydro-1,3-dimethyl Examples include -1- (2-methyl-2-phenylpropyl) -3-phenyl-1H-indane, which satisfies the condition (B).

Examples of the aromatic compound represented by the formula (2-7-2) include the following.
R ¹⁶ and R ¹⁷ are each independently a hydrocarbon group having 1 to 20 carbon atoms (provided that the total of R ¹⁶ and R ¹⁷ is 3 to 20 carbon atoms), and R ^{11 to} R ¹⁵ are A compound that is hydrogen (fills (B)).
2,2-diphenylbutane, 3,3-diphenylpentane, 3,3-diphenylhexane, 4,4-diphenylheptane, 5,5-diphenyloctane, 6,6-diphenylnonane, 1,1-diphenyl-1, 1-ditert-butyl-methane.

A compound in which R ¹⁶ and R ¹⁷ are combined to form a ring, and R ^{11 to} R ¹⁵ are hydrogen (satisfying (B)).
1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1-diphenyl-4-methylcyclohexane.
The following compounds may be used (they may be overlapped with the above-exemplified compounds, but will be represented by a structural formula).

A compound in which at least one of R ^{11 to} R ¹⁵ is a halogen or an unsubstituted or halogen-substituted hydrocarbon group having 1 to 20 carbon atoms (satisfies (A)).
1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene.
The following compounds may be used (they may be overlapped with the above-exemplified compounds, but will be represented by a structural formula).

R ¹⁷ is a hydrocarbon group having 1 to 20 carbon atoms (for example, an alkyl group having 1 to 20 carbon atoms, preferably a methyl group), and R ¹¹ and R ¹⁶ together form a ring. Compound (which satisfies (B)).
1-phenyl-1,3,3-trimethylindane.
The following compounds may be used (they may be overlapped with the above-exemplified compounds, but will be represented by a structural formula).

Among these, from the viewpoint of reducing properties on the initial negative electrode,
2,2-diphenylbutane, 3,3-diphenylpentane, 1,1-diphenyl-1,1-ditert-butyl-methane, 1,1-diphenylcyclohexane, 1,1-diphenylcyclopentane, 1,1- Diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene, 1-phenyl-1,3 , 3-trimethylindane.

  The following compounds can also be mentioned as preferable ones (they may be overlapped with the above-mentioned preferable compounds, but will be represented by the structural formula).

More preferred is
2,2-diphenylbutane, 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1 -Methyl-1-phenylethyl) -benzene, 1-phenyl-1,3,3-trimethylindane.

  The following compounds are also mentioned as more preferable ones (they may be overlapped with the more preferable compounds described above, but will be represented by the structural formula).

More preferred are 1,1-diphenylcyclohexane, 1,1-diphenyl-4-methylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl- 1-phenylethyl) -benzene, 1-phenyl-1,3,3-trimethylindane.
The following compounds are also mentioned as more preferable ones (they may be overlapped with the above-mentioned more preferable compounds, but will be shown by the structural formula).

  Particularly preferred are 1,1-diphenylcyclohexane, 1,3-bis (1-methyl-1-phenylethyl) -benzene, 1,4-bis (1-methyl-1-phenylethyl) -benzene, 1-phenyl. -1,3,3-trimethylindane, which is represented by the following structural formula.

  Most preferred is a 1-phenyl-1,3,3-trimethylindane compound, which is represented by the following structural formula.

The aromatic compound represented by Formula (2-7-2) may be used alone or in combination of two or more. In the total amount (100% by mass) of the non-aqueous electrolyte solution, the amount of the aromatic compound represented by the formula (2-7-2) (the total amount in the case of two or more types) is 0.001% by mass or more. Preferably, it is 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and can be 10% by mass or less, preferably 8% by mass. % Or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2.5% by mass or less. By being in the said range, the effect of this invention is easy to express and the resistance increase of a battery can be prevented.

(In Formula (2), R ⁵ represents a hydrocarbon group having 1 to 4 carbon atoms, and R ⁶ is an ethyl group, an n-propyl group, or an n-butyl group.)
The hydrocarbon group having 1 to 4 carbon atoms in R ⁵ is not particularly limited, but the carbon number is usually 1 or more, preferably 2 or more, and usually 4 or less, preferably 3 or less. Specific examples of the hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. Among these, alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, Vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group and the like, alkenyl groups having 2 to 3 carbon atoms, ethynyl group, 1-propynyl group, C2-C4 alkynyl groups such as 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group and the like are preferable, methyl group, ethyl group, n-propyl group, i-propyl group, n- Alkyl groups having 1 to 4 carbon atoms such as butyl group, sec-butyl group, i-butyl group and tert-butyl group are more preferable, and methyl group, ethyl group, n-propyl group and n-butyl group are more preferable. Echi Group, n- propyl group is particularly preferred.

R ⁶ is an ethyl group, an n-propyl group or an n-butyl group, preferably an ethyl group, an n-propyl group, more preferably an ethyl group.
Examples of the carboxylic acid ester represented by the above formula (2) include ethyl acetate, n-propyl acetate, n-butyl acetate, ethyl propionate, n-propyl propionate, n-butyl propionate, ethyl butyrate, and n-butyrate. Propyl, n-butyl butyrate, ethyl isobutyrate, n-propyl isobutyrate, n-butyl isobutyrate, ethyl valerate, n-propyl valerate, n-butyl valerate, ethyl hydroangelate, n-propyl hydroangelate N-butyl hydroangelic acid, ethyl isovalerate, n-propyl isovalerate, n-butyl isovalerate, ethyl pivalate, n-propyl pivalate, n-butyl pivalate, ethyl acrylate, acrylic acid n -Propyl, n-butyl acrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, Ethyl rotonic acid, n-propyl crotonic acid, n-butyl crotonic acid, ethyl 3-butenoate, n-propyl 3-butenoate, n-butyl 3-butenoate, ethyl 4-pentenoate, n-pentenoic acid n- Propyl, n-butyl 4-pentenoate, ethyl 3-pentenoate, n-propyl 3-pentenoate, n-butyl 3-pentenoate, ethyl 2-pentenoate, n-propyl 2-pentenoate, 2-pentenoic acid n-butyl, ethyl 2-propinate, n-propyl 2-propinate, n-butyl 2-propinate, ethyl 3-butyrate, n-propyl 3-butyrate, n-butyl 3-butyrate, 2- Ethyl butyrate, 2-butynoic acid n-propyl, 2-butynoic acid n-butyl, 4-pentynoic acid ethyl, 4-pentynoic acid n-propyl, 4-pentynoic acid n-butyl, 3-pentyne Ethyl, 3-pentyne acid n- propyl, 3-pentyne acid n- butyl, ethyl 2-pentyne acid, 2-pentyne acid n- propyl, 2-pentyne acid n- butyl and the like.

  Among these, ethyl acetate, n-propyl acetate, n-butyl acetate, ethyl propionate, n-propyl propionate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, n-butyl butyrate, ethyl isobutyrate, N-propyl isobutyrate, n-butyl isobutyrate, ethyl valerate, n-propyl valerate, n-butyl valerate, ethyl hydroangelate, n-propyl hydroangelate, n-butyl hydroangelate, isovaleric acid Ethyl, n-propyl isovalerate, n-butyl isovalerate, ethyl pivalate, n-propyl pivalate, n-butyl pivalate are preferred from the viewpoint of improving the initial properties, and ethyl acetate, n-propyl acetate, n-butyl acetate -Butyl, ethyl propionate, n-propyl propionate, n-butyl propionate, ethyl butyrate, n-probutyrate N-butyl butyrate, ethyl valerate, n-propyl valerate, n-butyl valerate, ethyl isovalerate, n-propyl isovalerate, n-butyl isovalerate, ethyl propionate, propionic acid More preferred are n-propyl, n-butyl propionate, ethyl butyrate, n-propyl butyrate, n-butyl butyrate, ethyl valerate, n-propyl valerate, n-butyl valerate, ethyl propionate, n-propionate More preferred are propyl, n-butyl propionate, ethyl butyrate, n-propyl butyrate and n-butyl butyrate.

The carboxylic acid ester represented by Formula (2) may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
The amount of the carboxylic acid ester represented by the formula (2) (the total amount in the case of two or more types) is preferably 100% by mass or more, more preferably 0.3% by mass or more, in 100% by mass of the electrolytic solution. More preferably, it is 0.4% by mass or more, preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and still more preferably 2%. It is at most 1 mass%, particularly preferably at most 1 mass%. In addition, when the carboxylic acid ester represented by the formula (2) is used as a non-aqueous solvent, the blending amount is preferably 1% by volume or more, more preferably 5% by volume or more, even more preferably in 100% by volume of the non-aqueous solvent. Is 10% by volume or more, still more preferably 20% by volume or more, and can be contained by 50% by volume or less, more preferably 45% by volume or less, still more preferably 40% by volume or less.

  The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the carboxylic acid ester represented by the formula (2) is from 1:99 to the point of forming a composite interface protective film on the negative electrode. 99: 1 is preferable, 5:95 to 95: 5 is more preferable, 10:90 to 90:10 is still more preferable, 20:80 to 80:20 is particularly preferable, and 30:70 to 70:30 is preferable. Highly preferred. When it mix | blends in this range, the side reaction in the positive / negative electrode of each additive can be suppressed efficiently, and a battery characteristic improves. In particular, it is useful for initial suppression and safety improvement during overcharge.

1-2-9. Cyclic compound having a plurality of ether bonds The cyclic compound having a plurality of ether bonds is not particularly limited as long as it is a cyclic compound having a plurality of ether bonds in the molecule, but is preferably represented by formula (2-9). It is a compound. The cyclic compound having a plurality of ether bonds contributes to the improvement of the high temperature storage characteristics of the battery. In the electrolytic solution of the present invention, the cyclic compound is used in combination with the aromatic carboxylic acid ester represented by the formula (1). Good initial characteristics can be maintained.

(Where
A ^{15 to} A ²⁰ independently represent a hydrogen atom, a fluorine atom, or a hydrocarbon group having 1 to 5 carbon atoms that may have a substituent. n ¹⁰¹ is an integer of 1 or more and 4 or less, and when n ¹⁰¹ is an integer of 2 or more, the plurality of A ¹⁷ and A ¹⁸ may be the same or different. )
Two members selected from A ^{15 to} A ²⁰ may be bonded to each other to form a ring. In this case, it is preferable to form a ring structure with A ¹⁷ and A ¹⁸ . The total number of carbon atoms of A ^{15 to} A ²⁰ is preferably 0 or more and 8 or less, more preferably 0 or more and 4 or less, still more preferably 0 or more and 2 or less, and particularly preferably 0 or more and 1 or less.

  As the substituent, a halogen atom, which may be substituted with a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, and a cyano group, an isocyanato group, an ether group, a carbonate group, a carbonyl group, Examples thereof include a carboxy group, an alkoxycarbonyl group, an acyloxy group, a sulfonyl group, a phosphantriyl group, and a phosphoryl group. Of these, a halogen atom, an alkoxy group, an alkyl group, an alkenyl group, an alkynyl group, which may be substituted with a halogen atom, an isocyanato group, a cyano group, an ether group, a carbonyl group, an alkoxycarbonyl group, an acyloxy group More preferably an alkyl group not substituted with a halogen atom, a cyano group, and an ether group.

In formula (2-9), n ¹⁰¹ is preferably an integer of 1 or more, 3 or less, more preferably an integer of 1 or more and 2 or less, and even more preferably n ¹⁰¹ is 2.
The hydrocarbon group having 1 to 5 carbon atoms in A ^{15 to} A ²⁰ is a monovalent hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, and an aryl group;
And divalent hydrocarbon groups such as an alkylene group, an alkenylene group, an alkynylene group, and an arylene group. Of these, an alkyl group and an alkylene group are preferable, and an alkyl group is more preferable.

As a specific example of the hydrocarbon group,
Methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl An alkyl group having 1 to 5 carbon atoms such as a group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group;
Vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group An alkenyl group having 2 to 5 carbon atoms, such as a group;
Carbon such as ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-pentynyl group, 2-pentynyl group, 3-pentynyl group and 4-pentynyl group An alkynyl group having a number of 2 or more and 5 or less;
Alkylene groups having 1 to 5 carbon atoms, such as methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group;
An alkenylene group having 2 to 5 carbon atoms, such as a vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2-pentenylene group;
Examples thereof include alkynylene groups having 2 to 5 carbon atoms such as ethynylene group, propynylene group, 1-butynylene group, 2-butynylene group, 1-pentynylene group and 2-pentynylene group. Of these, an alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group is preferable, and an ethylene group, a trimethylene group, a tetramethylene group, and a pentane are more preferable. An alkylene group having 2 to 5 carbon atoms, such as a methylene group, and more preferably an alkylene group having 3 to 5 carbon atoms, such as a trimethylene group, a tetramethylene group, and a pentamethylene group.

The hydrogen atom, fluorine atom, or hydrocarbon group having 1 to 5 carbon atoms in A ^{15 to} A ²⁰ is a group in which a hydrogen atom, a fluorine atom, or the above substituent is combined with the hydrocarbon group having 1 to 5 carbon atoms. Preferably, it is a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms which does not have a substituent, and an alkylene group having an ether structure in which part of the carbon chain of the alkylene group is substituted with an ether group. More preferably a hydrogen atom.
Examples of the cyclic compound having a plurality of ether bonds include the following compounds.

  Above all,

Etc. are preferred.

Is more preferable.
The cyclic compound which has a some ether bond may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios. The amount of the cyclic compound having a plurality of ether bonds (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, in 100% by mass of the electrolytic solution. More preferably, it is 0.1% by mass or more, particularly preferably 0.3% by mass or more, and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and further Preferably it is 2 mass% or less. When the above range is satisfied, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

1-3. Electrolyte There is no restriction | limiting in particular in electrolyte, What is well-known as electrolyte can be used arbitrarily. In the case of a lithium secondary battery, a lithium salt is usually used. Specifically, inorganic lithium salts such as LiPF ₆ , LiBF _4, LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiTaF ₆ , LiWF ₇ ; lithium tungstates such as LiWOF ₅ ; HCO ₂ Li, CH ₃ CO ₂ Li, _{CH 2 FCO 2 Li, CHF 2} CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 Carboxylic acid lithium salts such as CF ₂ CO ₂ Li; FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF _{3 CF 2 CF 2 SO 3 Li,} CF 3 CF 2 CF 2 CF 2 SO 3 sulfonate lithium salt such as Li _{; LiN (FCO) 2, LiN} (FCO) (FSO 2), LiN (FSO 2) 2, LiN (FSO 2) (CF 3 SO 2), LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO _{2) 2,} lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2) lithium imide such as Salts; Lithium methide salts such as LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ ; Lithium (such as lithium bis (malonato) borate, lithium difluoro (malonato) borate) Malonato) borate salts; lithium tris (malonato) phosphate, lithium difluorobis (malonato) Sufeto, lithium (Maronato) phosphate salts such as lithium tetrafluoro (Maronato) phosphate; _{other, LiPF 4 (CF 3) 2} , LiPF 4 (C 2 F 5) 2, LiPF 4 (CF 3 SO 2) 2, LiPF 4 (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ ( Fluorine-containing organic lithium salts such as CF ₃ SO ₂ ) ₂ and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ; Lithium oxalate borate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
And lithium oxalate phosphate salts such as lithium tetrafluorooxalato phosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate; and the like.

Among them, LiPF ₆ , LiSbF ₆ , LiTaF ₆ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _3, lithium difluorooxalatoborate, lithium Bis (oxalato) borate, lithium difluorobis (oxalato) phosphate, etc. Rate charge and discharge characteristics, high-temperature storage characteristics, particularly preferred from the viewpoint that an effect of improving the cycle characteristics and the like.

  The concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired, but the electric conductivity of the electrolyte solution is in a good range, and good battery performance is ensured. In view of this, the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, still more preferably 0.5 mol / L or more, and preferably Is 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less. If it is this range, since there is not too little lithium which is a charged particle and a viscosity can be made into an appropriate range, it will become easy to ensure favorable electrical conductivity.

  When two or more electrolytes are used in combination, at least one of them is preferably a salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate. More preferably, it is a salt selected from the group consisting of monofluorophosphate, difluorophosphate, oxalate and fluorosulfonate. Of these, lithium salts are preferred. The salt selected from the group consisting of monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate can be 0.01% by mass or more, preferably 0.1% by mass. % Or more, and can be 20% by mass or less, preferably 10% by mass or less.

The electrolyte preferably contains at least one selected from the group consisting of monofluorophosphates, difluorophosphates, borates, oxalates and fluorosulfonates and at least one of the other salts. . Other salts include the lithium salts exemplified above, and in particular LiPF ₆ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , and LiPF ₃ (C ₂ F ₅ ) ₃ are preferable, and LiPF ₆ is more preferable. The other salt may be 0.01% by mass or more, preferably 0.1% by mass or more, and 20% by mass from the viewpoint of ensuring an appropriate balance between the conductivity and viscosity of the electrolytic solution. Or less, preferably 15% by mass or less, more preferably 10% by mass or less.

  The total amount of the electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, still more preferably 0.5 mol / L or more in the non-aqueous electrolyte from the viewpoint of ensuring good battery performance. Moreover, it is preferably 3 mol / L or less, more preferably 2.5 mol / L or less, still more preferably 2.0 mol / L or less, and particularly preferably 1.5 mol / L or less.

1-3-1. Monofluorophosphate, difluorophosphate Monofluorophosphate and difluorophosphate are not particularly limited as long as each has at least one monofluorophosphate or difluorophosphate structure in the molecule. In the electrolytic solution of the present invention, by using together the aromatic carboxylic acid ester represented by the above formula (1) and one or more selected from monofluorophosphate and difluorophosphate, the initial charge / discharge of the battery Subsequent volume changes can be remarkably suppressed, and safety during overcharge can be further improved. In addition, the combined use can reduce the initial irreversible capacity of the battery and improve the discharge storage characteristics. At the same time, the battery can have excellent high temperature cycling characteristics.

The counter cation in the monofluorophosphate and difluorophosphate is not particularly limited, and lithium, sodium, potassium, magnesium, calcium, NR ¹²¹ R ¹²² R ¹²³ R ¹²⁴ (wherein R ^{121 to} R ¹²⁴ are independently And ammonium represented by a hydrogen atom or an organic group having 1 to 12 carbon atoms. The organic group having 1 to 12 carbon atoms represented by R ^{121 to} R ¹²⁴ of the ammonium is not particularly limited. A cycloalkyl group that may be substituted, an aryl group that may be substituted with a halogen atom or an alkyl group, a nitrogen-containing heterocyclic group that may have a substituent, and the like. Among these, R ^{121 to} R ¹²⁴ are preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, a nitrogen atom-containing heterocyclic group, or the like. As a counter cation, lithium, sodium, and potassium are preferable, and lithium is particularly preferable.

  Examples of monofluorophosphate and difluorophosphate include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. Lithium monofluorophosphate and lithium difluorophosphate are preferred, and lithium difluorophosphate is more preferred.

Monofluorophosphate and difluorophosphate may be used alone or in combination of two or more in any combination and ratio.
The amount of one or more selected from monofluorophosphate and difluorophosphate (the total amount in the case of two or more) can be 0.001% by mass or more, preferably 0.01% by mass or more. More preferably, it is 0.1% by mass or more, more preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and can be 5% by mass or less, preferably 3% by mass. Hereinafter, it is more preferably 2% by mass or less, further preferably 1.5% by mass or less, and particularly preferably 1% by mass or less. Within this range, the effect of improving the initial irreversible capacity is remarkably exhibited.

  The mass ratio of one or more selected from the aromatic carboxylic acid ester represented by the above formula (1), the monofluorophosphate, and the salt (total amount in the case of two or more) is 1:99 to 99: 1. Is preferable, 10:90 to 90:10 is more preferable, and 20:80 to 80:20 is particularly preferable. Within this range, the intended characteristics can be improved without degrading other battery characteristics.

1-3-2. Borate Borate is not particularly limited as long as it is a salt having at least one boron atom in the molecule. However, what corresponds to oxalate is 1-3-2. Not borate, but will be described later 1-3-3. Included in oxalate. In the electrolytic solution of the present invention, by using the aromatic carboxylic acid ester represented by the formula (1) and the borate in combination, the initial characteristics and the storage characteristics are improved, and further, the overcharge safety is excellent. A battery is obtained.

Examples of the counter cation in the borate include lithium, sodium, potassium, magnesium, calcium, rubidium, cesium, and barium, and lithium is particularly preferable.
As the borate, a lithium salt is preferable, and a lithium borate salt can also be suitably used. For example, LiBF ₄ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) _{2 and the} like. Among these, LiBF ₄ is more preferable because it has an effect of improving initial charge / discharge efficiency, high-temperature cycle characteristics, and the like.

A borate may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of borate (total amount in the case of two or more types) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably. Is 0.3% by mass or more, particularly preferably 0.4% by mass or more, and can be 10.0% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass. % Or less, more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less. Within this range, side reactions of the battery negative electrode are suppressed and resistance is hardly increased.

The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) and the borate is preferably 1:99 to 99: 1, more preferably 10:90 to 90:10, and 20:80 to 80: 20 is particularly preferred. Within this range, side reactions on the positive and negative electrodes in the battery are suppressed, and the resistance of the battery is difficult to increase.
Moreover, when borate and LiPF ₆ are used as the electrolyte, the ratio of the molar content of borate to the molar content of LiPF ₆ in the non-aqueous electrolyte is preferably 0.001 or more and 12 or less. 01-1.1 are more preferable, 0.01-1.0 are still more preferable, and 0.01-0.7 are more preferable. Within this range, side reactions on the positive and negative electrodes in the battery are suppressed, and the charge / discharge efficiency of the battery is improved.

1-3-3. Oxalate The oxalate is not particularly limited as long as it is a compound having at least one oxalic acid structure in the molecule. In the electrolytic solution of the present invention, a battery having improved initial characteristics and storage characteristics can be obtained by using the aromatic carboxylic acid ester represented by the formula (1) and oxalate together.

  As the oxalate, a metal salt represented by the formula (9) is preferable. This salt is a salt having an oxalato complex as an anion.

(Where
M ¹ is an element selected from the group consisting of Group 1, Group 2 and aluminum (Al) in the periodic table;
M ² is an element selected from the group consisting of transition metals, groups 13, 14 and 15 of the periodic table,
R ⁹¹ is a group selected from the group consisting of halogen, an alkyl group having 1 to 11 carbon atoms and a halogen-substituted alkyl group having 1 to 11 carbon atoms,
a and b are positive integers;
c is 0 or a positive integer;
d is an integer of 1-3. )
M ¹ is preferably lithium, sodium, potassium, magnesium, or calcium, particularly preferably lithium, from the viewpoint of battery characteristics when the electrolytic solution of the present invention is used in a lithium secondary battery.

M ² is particularly preferably boron or phosphorus from the viewpoint of electrochemical stability when used in a lithium secondary battery.
^Examples of R ⁹¹ include fluorine, chlorine, methyl group, trifluoromethyl group, ethyl group, pentafluoroethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, and the like. A trifluoromethyl group is preferred.

Examples of the metal salt represented by the formula (9) include the following.
Lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
Lithium oxalate phosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate;
Of these, lithium bis (oxalato) borate and lithium difluorobis (oxalato) phosphate are preferred, and lithium bis (oxalato) borate is more preferred.

One oxalate may be used alone, or two or more oxalates may be used in any combination and ratio.
The amount of oxalate (the total amount in the case of two or more types) can be 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably. Is 0.3% by mass or more and can be 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and particularly preferably 1% by mass. % Or less. Within this range, it is easy to control output characteristics, load characteristics, low temperature characteristics, cycle characteristics, high temperature storage characteristics, and the like.

The mass ratio of the aromatic carboxylic acid ester represented by the above formula (1) to the oxalate is 1:99.
-99: 1 are preferable, 10: 90-90: 10 are more preferable, and 20: 80-80: 20 are especially preferable. Within this range, side reactions on the positive and negative electrodes of the battery are suppressed in a balanced manner, and the battery characteristics are easily improved.

1-3-4. Fluorosulfonate The fluorosulfonate is not particularly limited as long as it is a salt having at least one fluorosulfonic acid structure in the molecule. In the electrolytic solution of the present invention, a battery having improved initial characteristics and storage characteristics can be obtained by using the aromatic carboxylic acid ester represented by the above formula (1) and the fluorosulfonate together.

The counter cation in the fluorosulfonate is not particularly limited, and lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, and NR ¹³¹ R ¹³² R ¹³³ R ¹³⁴ (wherein R ^{131 to} R ¹³⁴ are And each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms. For illustrative and preferred examples of R ¹³¹ to R ¹³⁴ may, ^R 131 ^{to R 134} in the 1-2-2 is applied. As a counter cation, lithium, sodium, and potassium are preferable, and lithium is particularly preferable.

  Examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, cesium fluorosulfonate, and lithium fluorosulfonate is preferable. An imide salt having a fluorosulfonic acid structure such as lithium bis (fluorosulfonyl) imide can also be used as the fluorosulfonic acid salt.

A fluorosulfonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The content of fluorosulfonate (total amount in the case of two or more) can be 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, More preferably, it is 0.3% by mass or more, particularly preferably 0.4% by mass or more, and can be 10% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, Preferably it is 2 mass% or less, Most preferably, it is 1 mass% or less. Within this range, there are few side reactions in the battery and resistance is hardly increased.

  The mass ratio of the aromatic carboxylic acid ester represented by the formula (1) and the fluorosulfonate is preferably 1:99 to 99: 1, more preferably 10:90 to 90:10, and 20:80 to 80 : 20 is particularly preferable. Within this range, side reactions in the battery are appropriately suppressed, and high temperature durability characteristics are unlikely to deteriorate.

1-4. Nonaqueous solvent There is no restriction | limiting in particular about the nonaqueous solvent in this invention, It is possible to use a well-known organic solvent. Specific examples include cyclic carbonates having no fluorine atom, chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, and sulfone compounds.

In this specification, the volume of the non-aqueous solvent is a measured value at 25 ° C., but the measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.
1-4-1. The cyclic carbonate which does not have a fluorine atom As a cyclic carbonate which does not have a fluorine atom, the cyclic carbonate which has a C2-C4 alkylene group is mentioned.

Specific examples of the cyclic carbonate having an alkylene group having 2 to 4 carbon atoms and having no fluorine atom include ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.
The cyclic carbonate which does not have a fluorine atom may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  The blending amount of the cyclic carbonate not having a fluorine atom is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. However, the blending amount when one kind is used alone is 100 volumes of a non-aqueous solvent. %, 5% by volume or more, more preferably 10% by volume or more. By setting this range, the decrease in electrical conductivity resulting from the decrease in the dielectric constant of the non-aqueous electrolyte is avoided, and the large current discharge characteristics, negative electrode stability, and cycle characteristics of the non-aqueous electrolyte secondary battery are good. It becomes easy to be in a range. Moreover, it is 95 volume% or less, More preferably, it is 90 volume% or less, More preferably, it is 85 volume% or less. By setting it as this range, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in ionic conductivity is suppressed, and as a result, the load characteristics of the non-aqueous electrolyte secondary battery are easily set in a favorable range.

1-4-2. Chain carbonate As the chain carbonate, a chain carbonate having 3 to 7 carbon atoms is preferable, and a dialkyl carbonate having 3 to 7 carbon atoms is more preferable.
Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl n-propyl carbonate, n-butyl methyl carbonate, isobutyl methyl carbonate, tert -Butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, tert-butyl ethyl carbonate and the like.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferable. is there.
Further, chain carbonates having a fluorine atom (hereinafter sometimes referred to as “fluorinated chain carbonate”) can also be suitably used.

The number of fluorine atoms contained in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or may be bonded to different carbons.
Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate and derivatives thereof, fluorinated ethyl methyl carbonate and derivatives thereof, and fluorinated diethyl carbonate and derivatives thereof.

Fluorinated dimethyl carbonate and derivatives thereof include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate, and the like. It is done.
Fluorinated ethyl methyl carbonate and derivatives thereof include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2 -Trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate, etc. are mentioned.

  Fluorinated diethyl carbonate and its derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2- Trifluoroethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2, Examples include 2,2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, and the like.

  A chain carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. The blending amount of the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily set to a favorable range. Become. Further, the chain carbonate is preferably 90% by volume or less, more preferably 85% by volume or less, in 100% by volume of the nonaqueous solvent. By setting the upper limit in this way, it is easy to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte and to make the large current discharge characteristics of the non-aqueous electrolyte secondary battery in a favorable range. .

1-4-3. Cyclic carboxylic acid ester As the cyclic carboxylic acid ester, those having 3 to 12 carbon atoms are preferable.
Specific examples include gamma butyrolactone, gamma valerolactone, gamma caprolactone, epsilon caprolactone, and the like. Among these, gamma butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

A cyclic carboxylic acid ester may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of the cyclic carboxylic acid ester is usually 5% by volume or more, more preferably 10% by volume or more, in 100% by volume of the non-aqueous solvent. If it is this range, it will become easy to improve the electrical conductivity of a non-aqueous electrolyte solution, and to improve the large current discharge characteristic of a non-aqueous electrolyte secondary battery. The amount of the cyclic carboxylic acid ester is preferably 50% by volume or less, more preferably 40% by volume or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

1-4-4. Ether compound As the ether compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms in which part of hydrogen may be substituted with fluorine is preferable.
As the chain ether having 3 to 10 carbon atoms,
Diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2, 2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2-trifluoroethyl) ether, (2-fluoroethyl) ) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, ethyl-n-propyl ether, ethyl (3-Fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-teto Fluoro -n- propyl) ether, ethyl (2,2,
3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propylether, (2-fluoroethyl) (3-fluoro-n-propyl) ether, (2-fluoroethyl) (3 , 3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3 , 3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propyl ether, (2,2,2-trifluoroethyl) (3-fluoro-n-propyl) ether , (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3-tetra (Luoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 1,1,2,2-tetrafluoroethyl -N-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (3,3,3- (Trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (1,1,2,2-tetra) Fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propylether, (n-propyl) (3-fluoro-n-propyl) ether, (n-propyl) ) (3 , 3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (n-propyl) (2,2,3,3,3 -Pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, (3-fluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (3- Fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl ) Ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) Ether, (3, 3, 3 -Trifluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (2,2,3,3-tetrafluoro-n-propyl) ether, (2, 2,3,3-tetrafluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (2,2,3,3,3-pentafluoro-n- Propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-trifluoroethoxy) methanemethoxy (1,1,2,2-tetra) Fluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2,2-trifluoroethoxy) methane, ethoxy (1,1 2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) methane, (2-fluoroethoxy) (1,1,2, , 2-tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methane, di (1 , 1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ethane, methoxy (2,2,2-trifluoroethoxy) ethane, methoxy (1,1,2, , 2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2 2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2-fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) Ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2,2-trifluoroethoxy) ethane, (2,2,2-trifluoroethoxy) (1 , 1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, etc. Can be mentioned.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,4-dioxane, and the like, and fluorinated compounds thereof.
Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether have high solvating ability to lithium ions and improve ion dissociation. Of these, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferable because they have low viscosity and give high ionic conductivity.

An ether type compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The compounding amount of the ether compound is usually in 100% by volume of the non-aqueous solvent, preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 15% by volume or more, and preferably 70% by volume or less. More preferably, it is 60 volume% or less, More preferably, it is 50 volume% or less. If it is this range, it is easy to ensure the improvement effect of the lithium ion dissociation degree of chain ether, and the improvement of the ionic conductivity derived from a viscosity fall. It is easy to avoid a situation where the capacity is reduced due to co-insertion.

1-4-5. Sulfone compound As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.
Examples of the cyclic sulfone having 3 to 6 carbon atoms include trimethylene sulfones, tetramethylene sulfones and hexamethylene sulfones which are monosulfone compounds;
Examples include disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones.

Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.
As the sulfolanes, sulfolane and / or sulfolane derivatives (hereinafter sometimes referred to as “sulfolanes” including sulfolane) are preferable. As the sulfolane derivative, one in which one or more hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable.

  Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methyl sulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ionic conductivity and high input / output characteristics.

In addition, as the chain sulfone having 2 to 6 carbon atoms,
Dimethylsulfone, ethylmethylsulfone, diethylsulfone, n-propylmethylsulfone, n-propylethylsulfone, di-n-propylsulfone, isopropylmethylsulfone, isopropylethylsulfone, diisopropylsulfone, n-butylmethylsulfone, n-butylethyl Sulfone, tert-butylmethylsulfone, tert-butylethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, monofluoroethylmethylsulfone, difluoroethylmethylsulfone, trifluoroethylmethylsulfone, pentafluoro Ethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone Perfluoroethyl methyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di (trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, tri Fluoromethyl-n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoro Ethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-tert-butyl sulfone, pen Trifluoroethyl -n- butyl sulfone, pentafluoroethyl -tert- butyl sulfone, and the like.

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, tert-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone Trifluoroethyl-n-butylsulfone, trifluoroethyl-tert-butylsulfone, trifluoromethyl-n-butylsulfone, trifluoromethyl-tert-butylsulfone, etc. have high ionic conductivity and high input / output characteristics. preferable.

A sulfone compound may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The compounding amount of the sulfone compound is usually 0.3% by volume or more, more preferably 1% by volume or more, still more preferably 5% by volume or more in 100% by volume of the non-aqueous solvent, and preferably 40%. Volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less. Within this range, durability improvement effects such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be set to an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging an aqueous electrolyte secondary battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

1-4-6. Composition of non-aqueous solvent As the non-aqueous solvent of the present invention, one of the above-exemplified non-aqueous solvents may be used alone, or two or more thereof may be used in any combination and ratio.
For example, as a preferable combination of the non-aqueous solvent, a combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate can be mentioned.

Among them, the total of the cyclic carbonate having no fluorine atom and the chain carbonate in the nonaqueous solvent is preferably 70% by volume or more, more preferably 80% by volume or more, and still more preferably 90% by volume or more, The ratio of the cyclic carbonate having no fluorine atom to the total of the cyclic carbonate and the chain carbonate is preferably 5% by volume or more, more preferably 10% by volume or more, and further preferably 15% by volume or more. Preferably it is 50 volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less, Most preferably, it is 25 volume% or less.

When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent may be improved.
For example, as a preferable combination of a cyclic carbonate having no fluorine atom and a chain carbonate,
Ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate and diethyl carbonate and ethyl methyl carbonate, ethylene carbonate And dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

  Among the combinations of cyclic carbonates and chain carbonates having no fluorine atom, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable, in particular, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, Those containing ethylene carbonate, symmetric chain carbonates and asymmetric chain carbonates such as ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate have cycle characteristics and large current discharge characteristics. This is preferable because of a good balance.

Among them, the asymmetric chain carbonate is preferably ethyl methyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
A combination in which propylene carbonate is further added to the combination of these ethylene carbonates and chain carbonates is also a preferable combination.
In the case of containing propylene carbonate, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, particularly preferably 95: 5 to 50:50. Furthermore, the proportion of propylene carbonate in the entire non-aqueous solvent is preferably 0.1% by volume or more, more preferably 1% by volume or more, still more preferably 2% by volume or more, and preferably 20% by volume or less, more preferably Is 8% by volume or less, more preferably 5% by volume or less.

It is preferable to contain propylene carbonate in this concentration range because the low temperature characteristics may be further improved while maintaining the combination characteristics of ethylene carbonate and chain carbonate.
When dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 25% by volume or more. Preferably it is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less. The load characteristics of the battery may be improved.

Above all, it contains dimethyl carbonate and ethyl methyl carbonate, and by increasing the content ratio of dimethyl carbonate over the content ratio of ethyl methyl carbonate, the electric conductivity of the electrolyte can be maintained, but the battery characteristics after high temperature storage are improved. This is preferable.
The volume ratio of dimethyl carbonate to ethyl methyl carbonate in all non-aqueous solvents (dimethyl carbonate / ethyl methyl carbonate) is 1.1 or more in terms of improving the electric conductivity of the electrolyte and improving the battery characteristics after storage. Is preferably 1.5 or more, more preferably 2.5 or more. The volume ratio (dimethyl carbonate / ethyl methyl carbonate) is preferably 40 or less, more preferably 20 or less, still more preferably 10 or less, and particularly preferably 8 or less, from the viewpoint of improving battery characteristics at low temperatures.

  In the combination mainly composed of a cyclic carbonate having no fluorine atom and a chain carbonate, a cyclic carboxylic acid ester, a chain carboxylic acid ester, a cyclic ether, a chain ether, a sulfur-containing organic solvent, You may mix other solvents, such as a phosphorus organic solvent and an aromatic fluorine-containing solvent.

1-5. Auxiliary Agent In the electrolyte battery of the present invention, an auxiliary agent may be appropriately used in addition to the above compound depending on the purpose. Examples of the auxiliary agent include cyclic carbonates having a carbon-carbon unsaturated bond shown below and other auxiliary agents.

1-5-1. Cyclic carbonate having carbon-carbon unsaturated bond Cyclic carbonate having carbon-carbon unsaturated bond (hereinafter sometimes referred to as “unsaturated cyclic carbonate”) includes a carbon-carbon double bond or a carbon-carbon triple bond. Any cyclic carbonate having a bond is not particularly limited, and any unsaturated carbonate can be used. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

Examples of the unsaturated cyclic carbonate include vinylene carbonates, aromatic carbonates, ethylene carbonates substituted with a substituent having a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, Catechol carbonates etc. are mentioned.
As vinylene carbonates, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4 , 5-diallyl vinylene carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro Examples include vinylene carbonate.

  Specific examples of the ethylene carbonate substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5- Vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl -5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate 4,5 diallyl carbonate, 4-methyl-5-allyl carbonate and the like.

Among them, preferred unsaturated cyclic carbonates for use in combination include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5- Diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4- Allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4- -5-ethynyl ethylene carbonate. Vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are preferable because they form a more stable interface protective film, and vinylene carbonate and vinyl ethylene carbonate are more preferable.

  The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 80 or more, more preferably 85 or more, and preferably 250 or less, more preferably 150 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily.

The production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.
An unsaturated cyclic carbonate may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. Moreover, the compounding quantity of unsaturated cyclic carbonate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The blending amount of the unsaturated cyclic carbonate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, in 100% by mass of the non-aqueous electrolyte solution. Further, it is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less, and particularly preferably 3% by mass or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics are reduced, the amount of gas generation is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid the situation.

1-5-2. Other auxiliary agents Known other auxiliary agents can be used in the electrolytic solution of the present invention. Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, anhydrous Carboxylic anhydrides such as itaconic acid, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; 3,9-divinyl-2,4,8,10-tetra Spiro compounds such as oxaspiro [5.5] undecane; sulfur-containing compounds such as N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; trimethyl phosphite, triethyl phosphite, triphosphite Phenyl, trimethyl phosphate, triethyl phosphate, lithium Phosphorus compounds such as triphenyl acid, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone , 1,3-dimethyl-2-imidazolidinone and nitrogen-containing compounds such as N-methylsuccinimide; hydrocarbon compounds such as heptane, octane, nonane, decane, cycloheptane and the like. These may be used alone or in combination of two or more. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved.

The blending amount of other auxiliary agents is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The other auxiliary agent is preferably 0.01% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte solution. Within this range, the effects of other auxiliaries can be sufficiently exhibited, and it is easy to avoid a situation in which battery characteristics such as high-load discharge characteristics deteriorate. The blending amount of other auxiliaries is more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, more preferably 3% by mass or less, still more preferably 1% by mass or less. .

2. Battery Configuration The electrolyte battery of the present invention is suitable for use as an electrolyte for a secondary battery, for example, a lithium secondary battery, among non-aqueous electrolyte secondary batteries. Hereinafter, a non-aqueous electrolyte secondary battery using the electrolyte of the present invention will be described.
The electrolyte battery of the present invention can take a known structure, and typically includes a negative electrode and a positive electrode capable of occluding and releasing metal ions (for example, lithium ions) and the above-described electrolytic solution of the present invention. Prepare.

2-1. Negative electrode The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release metal ions (for example, lithium ions). Specific examples include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like. These may be used individually by 1 type, and may be used together combining 2 or more types arbitrarily.

<Negative electrode active material>
Examples of the negative electrode active material include carbonaceous materials, alloy-based materials, lithium-containing metal composite oxide materials, and the like.
As a carbonaceous material used as a negative electrode active material,
(1) natural graphite,
(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous material and an artificial graphite material at least once in the range of 400 to 3200 ° C;
(3) a carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different crystallinities and / or has an interface in contact with the different crystalline carbonaceous materials,
(4) A carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different orientations and / or has an interface in contact with the carbonaceous materials having different orientations,
Is preferably a good balance between initial irreversible capacity and high current density charge / discharge characteristics. Moreover, the carbonaceous materials (1) to (4) may be used alone or in combination of two or more in any combination and ratio.

  As the artificial carbonaceous material and artificial graphite material of (2) above, natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, and those obtained by oxidizing these pitches, needle coke, pitch coke, and Carbon materials that are partially graphitized, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials and their carbides, or carbonizable organic materials are benzene, toluene, xylene, quinoline And a solution dissolved in a low-molecular organic solvent such as n-hexane, and carbides thereof.

As an alloy material used as the negative electrode active material, as long as lithium can be occluded / released, lithium alone, simple metals and alloys forming lithium alloys, or oxides, carbides, nitrides, silicides, sulfides thereof Any of compounds such as products or phosphides may be used and is not particularly limited. The single metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / metalloid elements (that is, excluding carbon), more preferably aluminum, silicon and tin (hereinafter referred to as “ Simple metals) and alloys or compounds containing these atoms (sometimes abbreviated as “specific metal elements”). These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  As a negative electrode active material having at least one kind of atom selected from a specific metal element, a metal simple substance of any one specific metal element, an alloy composed of two or more specific metal elements, one type or two or more specific types Alloys composed of metal elements and one or more other metal elements, as well as compounds containing one or more specific metal elements, and oxides, carbides, nitrides and silicides of the compounds And composite compounds such as sulfides or phosphides. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

  In addition, a compound in which these complex compounds are complexly bonded to several kinds of elements such as a simple metal, an alloy, or a nonmetallic element is also included. Specifically, for example, in silicon and tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. For example, in the case of tin, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not operate as a negative electrode, and a nonmetallic element may be used. it can.

  Among these negative electrode active materials, since the capacity per unit mass is large when a battery is formed, any one simple metal of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element In particular, silicon and / or tin metal simple substance, alloy, oxide, carbide, nitride and the like are preferable from the viewpoint of capacity per unit mass and environmental load.

  The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but a material containing titanium and lithium is preferable from the viewpoint of high current density charge / discharge characteristics, A lithium-containing composite metal oxide material containing titanium is more preferable, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as “lithium titanium composite oxide”). That is, it is particularly preferable to use a lithium titanium composite oxide having a spinel structure in a negative electrode active material for a non-aqueous electrolyte secondary battery because the output resistance is greatly reduced.

In addition, lithium or titanium of the lithium titanium composite oxide is at least selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. Those substituted with one element are also preferred.
The metal oxide is a lithium titanium composite oxide represented by the formula (A), and in the formula (A), 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, 0 ≦ It is preferable that z ≦ 1.6 because the structure upon doping and dedoping of lithium ions is stable.

_{Li x Ti y M z O 4} (A)
[In the formula (A), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb. ]
Among the compositions represented by the above formula (A),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
This structure is particularly preferable because of a good balance of battery performance.

Particularly preferred representative compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O in (c). ₄ . As for the structure of Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.

<Physical properties of carbonaceous materials>
When using a carbonaceous material as a negative electrode active material, it is desirable to have the following physical properties.

(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction by the Gakushin method of carbonaceous materials is preferably 0.335 nm or more, and is usually 0.360 nm or less. 350 nm or less is preferable, and 0.345 nm or less is more preferable. Further, the crystallite size (Lc) of the carbonaceous material obtained by X-ray diffraction by the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(Volume-based average particle size)
The mass-based average particle diameter of the carbonaceous material is a volume-based average particle diameter (median diameter) determined by a laser diffraction / scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and 7 μm. The above is particularly preferable, and is usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, and particularly preferably 25 μm or less.

If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to loss of initial battery capacity. On the other hand, when the above range is exceeded, when an electrode is produced by coating, an uneven coating surface tends to be formed, which may be undesirable in the battery production process.
The volume-based average particle size is measured by dispersing carbon powder in a 0.2% by weight aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction / scattering particle size distribution. This is carried out using a meter (LA-700 manufactured by Horiba, Ltd.).

(Raman R value, Raman half width)
The Raman R value of the carbonaceous material is a value measured using an argon ion laser Raman spectrum method, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1.5 or less, preferably 1.2 or less, more preferably 1 or less, and particularly preferably 0.5 or less.

Further, the Raman half-width in the vicinity of 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and usually 100 cm ⁻¹ or less, and 80 cm ⁻¹ or less. Preferably, 60 cm ⁻¹ or less is more preferable, and 40 cm ⁻¹ or less is particularly preferable.
The Raman R value and the Raman half width are indices indicating the crystallinity of the surface of the carbonaceous material, but the carbonaceous material has appropriate crystallinity from the viewpoint of chemical stability, and Li enters through charge and discharge. It is preferable that the crystallinity is such that the sites between the layers are not lost, that is, the charge acceptability is not lowered. In the case where the density of the negative electrode is increased by press after applying to the current collector, it is preferable to take account of this because crystals tend to be oriented in a direction parallel to the electrode plate. When the Raman R value or the Raman half width is in the above range, a suitable film can be formed on the negative electrode surface to improve the storage characteristics, cycle characteristics, and load characteristics, and the efficiency associated with the reaction with the nonaqueous electrolyte solution Reduction and gas generation can be suppressed.

The measurement of the Raman spectrum, using a Raman spectrometer (manufactured by JASCO Corporation Raman spectrometer), the sample is naturally dropped into the measurement cell and filled, and while irradiating the sample surface in the cell with argon ion laser light, This is done by rotating the cell in a plane perpendicular to the laser beam. For the obtained Raman spectrum, the intensity IA of the peak PA near 1580 cm ⁻¹ and 1
The intensity IB of the peak PB near 360 cm ⁻¹ is measured, and the intensity ratio R (R = IB / IA) is calculated.

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half width analysis: Background processing ・ Smoothing processing: Simple average, 5 points of convolution

(BET specific surface area)
BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · ^{g -1} or more, 0.7 m ² · ^{g -1} or more, 1. 0 m ² · ^{g -1} or more, and particularly preferably 1.5 m ² · ^{g -1} or more, generally not more than 100 m ² · ^{g -1,} preferably ^{25 m} 2 · ^{g -1} or less, 15 m ² · g ^-1 more preferably less, ^{10 m} 2 · ^{g -1} or less are especially preferred.

When the value of the BET specific surface area is in the above range, precipitation of lithium on the electrode surface can be suppressed, while gas generation due to reaction with the non-aqueous electrolyte can be suppressed.
The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately prepared so that the value of the relative pressure is 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used.

(Roundness)
When the circularity is measured as the degree of the sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”, and is theoretical when the circularity is 1. Become a true sphere. The circularity of the particles having a particle size of 3 to 40 μm in the range of the carbonaceous material is desirably closer to 1, and is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. As the high current density charge / discharge characteristics are larger, the filling property is improved and the resistance between the particles can be suppressed as the circularity is larger, so that the high current density charge / discharge characteristics are improved. Therefore, it is preferable that the circularity is as high as the above range.

  The circularity is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample was dispersed in a 0.2% by mass aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. The detection range is specified as 0.6 to 400 μm, and the particle size is measured in the range of 3 to 40 μm.

  The method for improving the circularity is not particularly limited, but a sphere-shaped sphere is preferable because the shape of the interparticle void when the electrode body is formed is preferable. Examples of spheroidizing treatment include a method of mechanically approaching a sphere by applying a shearing force and a compressive force, a mechanical / physical processing method of granulating a plurality of fine particles by the binder or the adhesive force of the particles themselves, etc. Is mentioned.

(Tap density)
The tap density of the carbonaceous material is usually 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and more preferably 1 g · cm ⁻³ or more. Particularly preferable, 2 g · cm ⁻³ or less is preferable, 1.8 g · cm ⁻³ or less is more preferable, and 1.6 g · cm ⁻³ or less is particularly preferable. When the tap density is in the above range, battery capacity can be ensured and increase in resistance between particles can be suppressed.

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the mass at that time and the mass of the sample.

(Orientation ratio)
The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. When the orientation ratio is in the above range, excellent high-density charge / discharge characteristics can be ensured. The upper limit of the above range is the theoretical upper limit value of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. Set the molding obtained by filling 0.47 g of the sample into a molding machine with a diameter of 17 mm and compressing it with 58.8 MN · m ^{-2 so} that it is flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the (110) diffraction and (004) diffraction peak intensities of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree / measurement range and step angle / measurement time:
(110) plane: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) plane: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds

(Aspect ratio (powder))
The aspect ratio of the carbonaceous material is usually 1 or more and usually 10 or less, preferably 8 or less, and more preferably 5 or less. Within the above range, streaking during electrode plate formation is suppressed, and more uniform coating is possible, so that excellent high current density charge / discharge characteristics can be ensured. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the carbonaceous material.

  The aspect ratio is measured by magnifying and observing the carbonaceous material particles with a scanning electron microscope. Carbonaceous material particles when three-dimensional observation is performed by selecting arbitrary 50 graphite particles fixed to the end face of a metal having a thickness of 50 μm or less and rotating and tilting the stage on which the sample is fixed. The longest diameter A and the shortest diameter B orthogonal thereto are measured, and the average value of A / B is obtained.

<Configuration and production method of negative electrode>
Any known method can be used for producing the electrode as long as the effects of the present invention are not significantly impaired. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to the negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.
In the case of using an alloy-based material, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a technique such as vapor deposition, sputtering, or plating is also used.

(Current collector)
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.
In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, and a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.
The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less, from the viewpoint of securing battery capacity and handling properties.

(Thickness ratio between current collector and negative electrode active material layer)
The ratio of the thickness of the current collector to the negative electrode active material layer is not particularly limited, but the value of “(the thickness of the negative electrode active material layer on one side immediately before the nonaqueous electrolyte injection) / (thickness of the current collector)” However, 150 or less is preferable, 20 or less is more preferable, 10 or less is particularly preferable, 0.1 or more is preferable, 0.4 or more is further preferable, and 1 or more is particularly preferable. When the ratio of the thickness of the current collector to the negative electrode active material layer is in the above range, battery capacity can be secured and heat generation of the current collector during high current density charge / discharge can be suppressed.

(Binder)
The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used in manufacturing the electrode.
Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, Rubber polymers such as NBR (acrylonitrile / butadiene rubber) and ethylene / propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate , Soft resinous polymers such as ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, etc. And a polymer composition having ion conductivity of alkali metal ions (particularly lithium ions). These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10 mass% or less is still more preferable, and 8 mass% or less is especially preferable. When the ratio of the binder to the negative electrode active material is within the above range, the battery capacity and the strength of the negative electrode can be sufficiently secured.

In particular, when a rubbery polymer typified by SBR is contained as a main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0 .6% by mass or more is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Moreover, when the main component contains a fluorine-based polymer typified by polyvinylidene fluoride, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. Preferably, it is usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as necessary. Alternatively, either an aqueous solvent or an organic solvent may be used.
Examples of the aqueous solvent include water and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N- Examples include dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like.

  In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the thickener and slurry it using a latex such as SBR. In addition, these solvents may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

(Thickener)
A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  Furthermore, when using a thickener, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Moreover, it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is still more preferable. When the ratio of the thickener to the negative electrode active material is in the above range, it is possible to suppress a decrease in battery capacity and an increase in resistance, and it is possible to ensure good coatability.

(Electrode density)
The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more, and 1.2 g · cm ⁻³ or more. but more preferably, particularly preferably 1.3 g · ^{cm -3} or more, preferably 2.2 g · ^{cm -3} or less, more preferably 2.1 g · ^{cm -3} or less, 2.0 g · ^{cm -3} or less Further preferred is 1.9 g · cm ⁻³ or less. When the density of the negative electrode active material existing on the current collector is within the above range, the negative electrode active material particles are prevented from being destroyed, and an increase in initial irreversible capacity or to the vicinity of the current collector / negative electrode active material interface. While the deterioration of the high current density charge / discharge characteristics due to the reduced permeability of the non-aqueous electrolyte solution can be suppressed, the decrease in battery capacity and the increase in resistance can be suppressed.

(Thickness of negative electrode plate)
The thickness of the negative electrode plate is designed according to the positive electrode plate to be used, and is not particularly limited. However, the thickness of the composite layer obtained by subtracting the thickness of the metal foil of the core is usually 15 μm or more, preferably 20 μm or more. More preferably, it is 30 μm or more, and usually 300 μm or less, preferably 280 μm or less, more preferably 250 μm or less.

(Surface coating of negative electrode plate)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said negative electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

2-2. Positive electrode <Positive electrode active material>
The positive electrode active material used for the positive electrode is described below.
(composition)
The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release metal ions (for example, lithium ions). For example, a material containing lithium and at least one transition metal is preferable. Specific examples include lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.

V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable as the transition metal of the lithium transition metal composite oxide. Specific examples include lithium-cobalt composite oxides such as LiCoO ₂ and LiNiO ₂ . Lithium / nickel composite oxides, LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO _{4 and} other lithium / manganese composite oxides, LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O lithium-nickel-manganese-cobalt composite oxides such as _2, a part of Na of the subject become transition metal atoms in these lithium transition metal complex oxide, K, B, F, Al , Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W, and the like. As the substituted ones, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _{0 .45} Co _0.10 Al _0.45 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4 and the} like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , Iron phosphates such as LiFeP ₂ O _7, cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn, Fe , Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other elements.

  In addition, it is preferable to include lithium phosphate in the positive electrode active material because continuous charge characteristics are improved. Although there is no restriction | limiting in the use of lithium phosphate, It is preferable to mix and use said positive electrode active material and lithium phosphate. The lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass with respect to the total of the positive electrode active material and lithium phosphate. %, And the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 5% by mass or less.

(Surface coating)
Moreover, you may use what the substance of the composition different from this adhered to the surface of the said positive electrode active material. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

These surface adhering substances are, for example, dissolved or suspended in a solvent and impregnated and added to the positive electrode active material,
According to a method of drying, a method in which a surface adhering substance precursor is dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, and then reacted by heating, a method of adding to the positive electrode active material precursor and firing simultaneously, etc. It can be made to adhere to the positive electrode active material surface. In addition, when making carbon adhere, the method of making carbonaceous adhere mechanically later in the form of activated carbon etc. can also be used, for example.

The amount of the surface adhering substance is by mass with respect to the positive electrode active material, preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more, and the upper limit, preferably 20% or less, more preferably as the lower limit. Is used at 10% or less, more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the electrolyte solution on the surface of the positive electrode active material and can improve the battery life. However, when the amount of the adhering quantity is too small, the effect is not sufficiently manifested. If it is too high, the resistance may increase in order to inhibit the entry and exit of lithium ions.
In the present invention, a material having a composition different from that attached to the surface of the positive electrode active material is also referred to as a “positive electrode active material”.

(shape)
Examples of the shape of the particles of the positive electrode active material include a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, and a column shape as conventionally used. Moreover, primary particles may aggregate to form secondary particles.

(Tap density)
The tap density of the positive electrode active material is preferably 0.5 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 1.0 g / cm ³ or more. When the tap density of the positive electrode active material is within the above range, the amount of the dispersion medium and the necessary amount of the conductive material and the binder necessary for forming the positive electrode active material layer can be suppressed. As a result, the filling rate of the positive electrode active material and the battery Capacity can be secured. By using a complex oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. In general, the tap density is preferably as high as possible, and there is no particular upper limit. However, the tap density is preferably 4.0 g / cm ³ or less, more preferably 3.7 g / cm ³ or less, and still more preferably 3.5 g / cm ³ or less. When it is within the above range, it is possible to suppress a decrease in load characteristics.
In the present invention, the tap density is defined as the powder packing density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is put in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. Ask.

(Median diameter d50)
The median diameter d50 of the positive electrode active material particles (secondary particle diameter when primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably. Is 0.8 μm or more, most preferably 1.0 μm or more, and the upper limit is preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, and most preferably 22 μm or less. Within the above range, a high tap density product can be obtained and battery performance degradation can be suppressed. On the other hand, when producing a positive electrode for a battery, that is, when an active material, a conductive material, a binder, etc. are slurried with a solvent and applied in a thin film form Problems such as streaking can be prevented. Here, by mixing two or more positive electrode active materials having different median diameters d50, it is possible to further improve the filling property at the time of producing the positive electrode.

  In the present invention, the median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. When LA-920 manufactured by HORIBA is used as a particle size distribution meter, a 0.1% by mass sodium hexametaphosphate aqueous solution is used as a dispersion medium for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. Measured.

(Average primary particle size)
When primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.8. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and most preferably 2 μm or less. When it is in the above range, powder filling property and specific surface area can be secured and deterioration of battery performance can be suppressed, while reversibility of charge and discharge can be secured by obtaining appropriate crystallinity. .

  In the present invention, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles and obtained by taking the average value. It is done.

(BET specific surface area)
BET specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more, more preferably 0.2 m ² / g or more, further preferably 0.3 m ² / g or more, the upper limit is ^{50 m} 2 / g or less , Preferably 40 m ² / g or less, more preferably 30 m ² / g or less. When the BET specific surface area is in the above range, the battery performance can be secured and the applicability of the positive electrode active material can be kept good.
In the present invention, the BET specific surface area is determined by using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 150 ° C. for 30 minutes under nitrogen flow, and then atmospheric pressure. It is defined by a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas accurately prepared so that the value of the relative pressure of nitrogen to 0.3 is 0.3.

(Method for producing positive electrode active material)
As a manufacturing method of the positive electrode active material, a general method is used as a manufacturing method of the inorganic compound. In particular, various methods are conceivable for producing a spherical or elliptical active material. For example, a transition metal raw material is dissolved or ground and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, dried as necessary, and then added with a Li source such as LiOH, Li ₂ CO ₃ , LiNO _{3 and the} like, and then fired at a high temperature to obtain an active material. .

For the production of the positive electrode, the positive electrode active material may be used alone, or one or more of the different compositions may be used in any combination or ratio. As a preferable combination in this case, a combination of LiCoO ₂ and LiMn ₂ O ₄ such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ or a part of this Mn substituted with another transition metal or the like Or a combination with LiCoO ₂ or a part of this Co substituted with another transition metal or the like.

<Configuration and manufacturing method of positive electrode>
The structure of the positive electrode will be described below. In the present invention, the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. Manufacture of the positive electrode using a positive electrode active material can be performed by a conventional method. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form are pressure-bonded to a positive electrode current collector, or these materials are liquid media A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.

The content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. Moreover, an upper limit becomes like this. Preferably it is 99 mass% or less, More preferably, it is 98 mass% or less. Within the above range, the electric capacity of the positive electrode active material in the positive electrode active material layer can be secured, and the strength of the positive electrode can be maintained. Application,
The positive electrode active material layer obtained by drying is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material. Density of the positive electrode active material layer is preferably 1.5 g / cm ³ or more as a lower limit, more preferably 2 g / cm ^3, and even more preferably at 2.2 g / cm ³ or more, the upper limit is preferably 5 g / cm ^{It is 3} or less, more preferably 4.5 g / cm ³ or less, and still more preferably 4 g / cm ³ or less. Within the above range, good charge / discharge characteristics can be obtained, and an increase in electrical resistance can be suppressed.

(Conductive material)
A known conductive material can be arbitrarily used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and the upper limit is usually 50% by mass or less, preferably It is used so as to contain 30% by mass or less, more preferably 15% by mass or less. Sufficient electrical conductivity and battery capacity can be ensured within the above range.

(Binder)
The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material that can be dissolved or dispersed in the liquid medium used during electrode production may be used. Resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, isoprene rubber , Rubber polymers such as butadiene rubber and ethylene-propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / Ethylene copolymer, styrene Thermoplastic elastomeric polymer such as isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer Soft resinous polymers such as polymers; Fluoropolymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers; alkali metal ions (especially lithium ions) And a polymer composition having ion conductivity. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and the upper limit is usually 80% by mass or less, preferably Is 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. When the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. On the other hand, if it is too high, battery capacity and conductivity may be reduced.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it is a solvent that can dissolve or disperse the positive electrode active material, the conductive material, the binder, and the thickener used as necessary. However, either an aqueous solvent or an organic solvent may be used. Examples of the aqueous medium include water and a mixed medium of alcohol and water. Examples of the organic medium include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; Esters such as methyl acetate and methyl acrylate; Amines such as diethylenetriamine and N, N-dimethylaminopropylamine; Ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) and dimethyl Examples include amides such as formamide and dimethylacetamide; aprotic polar solvents such as hexamethylphosphalamide and dimethyl sulfoxide.

  In particular, when an aqueous medium is used, it is preferable to make a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios. When a thickener is further added, the ratio of the thickener to the active material is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more. The upper limit is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. When it is in the above range, good coatability can be obtained, and a decrease in battery capacity and an increase in resistance can be suppressed.

(Current collector)
The material of the positive electrode current collector is not particularly limited, and a known material can be arbitrarily used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. Of these, metal materials, particularly aluminum, are preferred.

  Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, and foam metal in the case of a metal material. A thin film, a carbon cylinder, etc. are mentioned. Of these, metal thin films are preferred. In addition, you may form a thin film suitably in mesh shape. Although the thickness of the thin film is arbitrary, from the viewpoint of strength and handleability as a current collector, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and the upper limit is usually 1 mm or less, preferably 100 μm or less. More preferably, it is 50 μm or less.

Moreover, it is also preferable from the viewpoint of reducing the electronic contact resistance between the current collector and the positive electrode active material layer that a conductive additive is applied to the surface of the current collector. Examples of the conductive assistant include noble metals such as carbon, gold, platinum, and silver.
The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is 20 The lower limit is preferably 15 or less, most preferably 10 or less, and the lower limit is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. Above this range, the current collector may generate heat due to Joule heat during high current density charge / discharge. Within the above range, heat generation of the current collector during high current density charge / discharge can be suppressed, and battery capacity can be secured.

(Electrode area)
When using the electrolytic solution of the present invention, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case from the viewpoint of increasing the stability at high output and high temperature. Specifically, the sum of the electrode areas of the positive electrode with respect to the surface area of the exterior of the secondary battery is preferably 15 times or more, more preferably 40 times or more. The outer surface area of the outer case is the total area obtained by calculation from the vertical, horizontal, and thickness dimensions of the case part filled with the power generation element excluding the protruding part of the terminal in the case of a bottomed square shape. . In the case of a bottomed cylindrical shape, the geometric surface area approximates the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder. The total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in the structure in which the positive electrode mixture layer is formed on both sides via the current collector foil. , The sum of the areas where each surface is calculated separately.

(Thickness of positive plate)
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer obtained by subtracting the metal foil thickness of the core material is preferably as a lower limit with respect to one side of the current collector. Is 10 μm or more, more preferably 20 μm or more, and the upper limit is preferably 500 μm or less, more preferably 450 μm or less.

(Positive electrode surface coating)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said positive electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.
2-3. Separator Normally, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the electrolytic solution of the present invention is usually used by impregnating this separator.

The material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. Among them, a resin, glass fiber, inorganic material, etc., which is formed of a material that is stable with respect to the electrolytic solution of the present invention, is used, and it is preferable to use a porous sheet or a nonwoven fabric-like material excellent in liquid retention. .
As materials for the resin and glass fiber separator, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferred, polyolefins are more preferred, and polypropylenes are particularly preferred. One of these materials may be used alone, or two or more of these materials may be used in any combination and ratio, or those laminated may be used. A specific example of a laminate of two or more kinds in any combination includes a three-layer separator in which polypropylene, polyethylene, and polypropylene are laminated in this order.

The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. Within the above range, insulation and mechanical strength can be secured, while battery performance such as rate characteristics and energy density can be secured.
Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Moreover, it is 90% or less normally, 85% or less is preferable and 75% or less is still more preferable. When the porosity is in the above range, insulation and mechanical strength can be secured, while film resistance can be suppressed and good rate characteristics can be obtained.

  Moreover, although the average pore diameter of a separator is also arbitrary, it is 0.5 micrometer or less normally, 0.2 micrometer or less is preferable, and it is 0.05 micrometer or more normally. If the average pore diameter exceeds the above range, a short circuit tends to occur. When the average pore diameter is in the above range, the film resistance can be suppressed and good rate characteristics can be obtained while preventing a short circuit. On the other hand, as inorganic materials, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those having a particle shape or fiber shape are used. .

  As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. In the thin film shape, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above-mentioned independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

2-4. Battery design <Electrode group>
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed through the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape through the separator. Either is acceptable. The ratio of the mass of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. . When the electrode group occupancy is in the above range, the battery capacity can be secured, the charge / discharge repeatability and the high temperature storage accompanying the increase in internal pressure are suppressed, and further the operation of the gas release valve is prevented. Can do.

<Current collection structure>
The current collecting structure is not particularly limited, but is preferably a structure that reduces the resistance of the wiring portion and the joint portion. In the case where the electrode group has the above laminated structure, a structure formed by bundling the metal core portions of the electrode layers and welding them to the terminals is preferably used. When the area of one electrode increases, the internal resistance increases. Therefore, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance. When the electrode group has the winding structure described above, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode, respectively, and bundling the terminals.

<Exterior case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, a nickel-plated steel plate, stainless steel, aluminum, an aluminum alloy, a metal such as a magnesium alloy, or a laminated film (laminate film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.

  In an exterior case using metals, the metal is welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed sealed structure, or a caulking structure using the above metals via a resin gasket. Things. Examples of the outer case using the laminate film include a case where a resin-sealed structure is formed by heat-sealing resin layers. In order to improve sealing performance, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a sealed structure, a metal and a resin are joined, so that a resin having a polar group or a modified group having a polar group introduced as an intervening resin is used. Resins are preferably used. The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

<Protective element>
As a protective element, PTC (Positive Temperature Coefficient) whose resistance increases when abnormal heat generation or excessive current flows, temperature fuse, thermistor, shuts off the current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature at abnormal heat generation A valve (current cutoff valve) or the like can be used. It is preferable to select a protective element that does not operate under normal use at a high current, and it is more preferable that the protective element is designed so as not to cause abnormal heat generation or thermal runaway even without the protective element.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
The structure of the aromatic carboxylic acid ester represented by the formula (1) used in this example is shown below.

  Moreover, the structure of the other used compound is shown below.

<Example 1-1 and Comparative Examples 1-1 to 1-3>
[Example 1-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (also referred to as “EC”), ethyl methyl carbonate (also referred to as “EMC”) and diethyl carbonate (also referred to as “DEC”). LiPF ₆ as an electrolyte was dissolved at a rate of 1.2 mol / L to obtain a basic electrolytic solution. Further, 0.5% by mass of the compound (2-1) and 0.5% by mass of triethylphosphonoacetate (also referred to as “MP1”) were added as additives to the basic electrolytic solution, and Example 1-1 was added. A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). Thereafter, in a state of being pressed by being sandwiched between glass plates, a constant current charge was performed at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then a constant current discharge was performed to 0.2 V at 0.2 C. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, the battery was discharged to 3V with a constant current of 0.2C. . Next, CC-CV charge (0.05 C cut) to 4.40 V at 0.2 C, and then discharge again to 3 V at 0.2 C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.40V at 0.2C, the battery was immersed in an ethanol bath to measure the volume, and the change from the initial battery volume was taken as the initial gas amount. Then, it discharged to 3V at 0.2C, and this was made into the initial 0.2C capacity | capacitance. Furthermore, after CC-CV charge (0.05C cut) to 4.40V at 0.2C, it discharged to 3V at 0.5C, and this was made into the initial 0.5C capacity | capacitance. Then, the ratio of the initial 0.5C capacity to the initial 0.2C capacity was determined, and this was used as the initial rate characteristic (%).
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charging (0.05C cut) to 25 ° C to 4.40V at 0.2C, then at 85 ° C for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage durability test was CC-CV charged to 0.05 V at a constant current of 0.2 C at 25 ° C. (0.05 C cut), and then discharged again to 3 V at 0.2 C. This was the recovery 0.2 C capacity.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 1 as relative values when Comparative Example 1-1 is 100.0%. The same applies to the following.

[Comparative Example 1-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that the electrolyte solution containing no compound (2-1) and MP1 was used in the electrolyte solution of Example 1-1. Evaluation was performed.
[Comparative Example 1-2]
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that the electrolyte solution containing no MP1 was used in the electrolyte solution of Example 1-1, and the above evaluation was performed.

[Comparative Example 1-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1-1 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 1-1. Carried out.

  From Table 1, when the non-aqueous electrolyte solution of Example 1-1 according to the present invention is used, the aromatic carboxylic acid ester and the phosphonic acid ester represented by the formula (1) are not added simultaneously (Comparative Example 1). Compared to -1), the initial rate characteristics are excellent, and the recovery 0.2 C capacity after the high temperature storage durability test is also excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.

  In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 1-2), the initial rate characteristics are improved as compared with Comparative Example 1-1, but the initial gas amount is less than that of Example. Increased from 1-1. Further, the recovery 0.2C capacity is improved as compared with Comparative Example 1-1, but the improvement effect is small and inferior to Example 1-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.

When the phosphonic acid ester is used alone (Comparative Example 1-3), the initial rate characteristic is improved as compared with Comparative Example 1-1, but the initial gas amount is increased as compared with Example 1-1. Further, the recovery 0.2C capacity is improved as compared with Comparative Example 1-1, but the improvement effect is small and inferior to Example 1-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester and the phosphonic acid ester represented by the formula (1).

<Example 2-1 and Comparative Examples 2-1 to 2-3>
[Example 2-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Furthermore, to this basic electrolyte solution, 0.5% by mass of the compound (2-1) and 0.5% by mass of monofluoroethylene carbonate (also referred to as “MP2”) were added as additives. A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). Thereafter, in a state of being pressed by being sandwiched between glass plates, a constant current charge was performed at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then a constant current discharge was performed to 0.2 V at 0.2 C. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.4V at 0.2C, the volume is measured by immersing the non-aqueous electrolyte secondary battery in an ethanol bath, and the change from the initial battery volume is calculated. The initial gas amount was used.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Overcharge characteristics evaluation after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high temperature storage endurance test was CC-CV charged (at 0.05 C cut) to 4.4 V at a constant current of 0.2 C at 25 ° C., and then immersed in an ethanol bath. The battery volume before overcharge was determined from the buoyancy. Thereafter, overcharging was performed at a constant current up to 5.0 V at 0.2 C at 45 ° C. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the amount of change from the battery volume before overcharge was defined as the amount of overcharge gas.

Note that the greater the amount of overcharged gas, the earlier the safety valve can be activated in a battery that activates the safety valve by detecting this when the internal pressure abnormally increases due to an abnormality such as overcharging. As a result, battery safety during overcharge can be ensured.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high temperature storage durability test, and overcharge characteristic evaluation after high temperature storage durability test were performed. The evaluation results are shown in Table 2 as relative values when Comparative Example 2-1 is 100.0%. The same applies to the following.

[Comparative Example 2-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 2-1, except that the electrolyte solution containing no compound (2-1) and MP2 was used in the electrolyte solution of Example 2-1. Evaluation was performed.
[Comparative Example 2-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 2-1, except that an electrolyte solution containing no MP2 was used in the electrolyte solution of Example 2-1, and the above evaluation was performed.

[Comparative Example 2-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 2-1, except that an electrolyte containing no compound (2-1) was used in the electrolyte of Example 2-1, and the above evaluation was performed. Carried out.

  From Table 2, when the non-aqueous electrolyte solution of Example 2-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the fluorine-containing cyclic carbonate are not added simultaneously (Comparative Example). Compared to 2-1), the initial gas amount is small, and the overcharge gas amount after the high-temperature storage durability test is large. That is, it is possible to provide a battery excellent in initial battery characteristics and evaluation of overcharge characteristics after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 2-2), the initial gas amount is increased as compared with Comparative Example 2-1. Furthermore, although the amount of overcharge gas increases compared with the comparative example 2-1, the improvement effect is small and is inferior compared with the example 2-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
Further, when the fluorine-containing cyclic carbonate is used alone (Comparative Example 2-3), the initial gas amount is smaller than that of Comparative Example 2-1, but the improvement effect is small and inferior to that of Example 2-1. . Furthermore, the amount of overcharged gas is smaller than that of Comparative Example 2-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the fluorine-containing cyclic carbonate.

<Example 3-1 and Comparative Examples 3-1 to 3-3>
[Example 3-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Further, 0.5% by mass of the compound (2-1) and 0.5% by mass of lithium fluorosulfonate (also referred to as “MP3”) were added as additives to the basic electrolytic solution, and Example 3-1 A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, CC-CV charge (0.05 C cut) to 4.4 V was performed at 0.2 C, and then discharged to 3.0 V at 1 C, which was defined as the initial 1 C capacity.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage endurance test is 4 at a constant current of 0.2 C at 25 ° C.
. After CC-CV charge to 4V (0.05C cut), it was discharged again to 3.0V at 0.2C, and this was made a recovery 0.2C capacity.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 3 as relative values when Comparative Example 3-1 is 100.0%. The same applies to the following.

[Comparative Example 3-1]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 3-1, except that the electrolyte solution containing no compound (2-1) and MP3 was used in the electrolyte solution of Example 3-1. Evaluation was performed.
[Comparative Example 3-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 3-1, except that an electrolyte solution containing no MP3 was used in the electrolyte solution of Example 3-1, and the above evaluation was performed.

[Comparative Example 3-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 3-1, except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 3-1, and the above evaluation was performed. Carried out.

  From Table 3, when the non-aqueous electrolyte solution of Example 3-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the fluorosulfonate are not added simultaneously (Comparative Example) Compared to 3-1), the initial 1 C capacity is excellent, and the recovery 0.2 C capacity after the high temperature storage durability test is also excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.

  In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 3-2), the initial 1C capacity is improved as compared with Comparative Example 3-1, but the improvement effect is small. It is inferior to Example 3-1. Further, the recovery 0.2C capacity is improved as compared with Comparative Example 3-1, but the improvement effect is small and inferior to Example 3-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.

Further, when the fluorosulfonate is used alone (Comparative Example 3-3), the initial 1C capacity is improved as compared with Comparative Example 3-1, but the improvement effect is small and inferior to Example 3-1. . Further, the recovery 0.2C capacity is improved as compared with Comparative Example 3-1, but the improvement effect is small and inferior to Example 3-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the fluorosulfonate.

<Example 4-1 and Comparative Examples 4-1 to 4-3>
[Example 4-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Furthermore, 0.5% by mass of the compound (2-1) and 0.5% by mass of 1,3-bis (isocyanatomethyl) cyclohexane (also referred to as “MP4”) are added as additives to the basic electrolyte. Thus, a non-aqueous electrolyte solution of Example 4-1 was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). Thereafter, in a state of being pressed by being sandwiched between glass plates, a constant current charge was performed at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then a constant current discharge was performed to 0.2 V at 0.2 C. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the volume was measured by immersing the battery in an ethanol bath, and the change from the initial battery volume was taken as the initial gas amount.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high temperature storage endurance test is CC-CV charged to 0.05 V at a constant current of 0.2 C at 25 ° C. (0.05 C cut), and then to 3.0 V at 0.2 C. It was discharged again, and this was set to a recovery 0.2 C capacity.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 4 as relative values when Comparative Example 4-1 is 100.0%. The same applies to the following.

[Comparative Example 4-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4-1, except that the electrolyte solution containing no compound (2-1) and MP4 was used in the electrolyte solution of Example 4-1. Evaluation was performed.
[Comparative Example 4-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4-1, except that an electrolyte solution containing no MP4 was used in the electrolyte solution of Example 4-1, and the above evaluation was performed.

[Comparative Example 4-3]
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 4-1, except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 4-1, and the above evaluation was performed. Carried out.

  From Table 4, when the non-aqueous electrolyte solution of Example 4-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the organic compound having an isocyanate group are not simultaneously added ( Compared to Comparative Example 4-1), the initial gas amount is small, and the recovery 0.2 C capacity after the high temperature storage durability test is also excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 4-2), the initial gas amount is increased as compared with Comparative Example 4-1. Further, the recovery 0.2C capacity increases as compared with Comparative Example 4-1, but the improvement effect is small and inferior to Example 4-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
Moreover, when the organic compound which has an isocyanate group is used independently (Comparative Example 4-3), although the amount of initial gas decreases compared with Comparative Example 4-1, it is inferior compared with Example 4-1. Further, the recovery 0.2C capacity is improved as compared with Comparative Example 4-1, but the improvement effect is small and inferior to Example 4-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the organic compound having an isocyanate group.

<Example 5-1 and Comparative Examples 5-1 to 5-3>
[Example 5-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Furthermore, 0.5% by mass of the compound (2-1) and 0.5% by mass of adiponitrile (also referred to as “MP5”) were added as additives to the basic electrolytic solution, and the non-aqueous system of Example 5-1 An electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Then, CC-CV charge (0.05C cut) to 4.4V at 0.2C, then discharge to 3.0V at 0.5C, and determine the ratio of discharge capacity to the charge capacity at this time, The efficiency was 0.5C (%).
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage endurance test was CC-CV charged to 0.05 V at a constant current of 0.2 C at 25 ° C. (0.05 C cut), and then to 3.0 V at 0.05 C. The battery was discharged again, the ratio of the discharge capacity to the charge capacity at this time was determined, and this was taken as the recovery 0.05C efficiency (%).
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 5 as relative values when Comparative Example 5-1 is set to 100.0%. The same applies to the following.

[Comparative Example 5-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 5-1, except that the electrolyte solution containing no compound (2-1) and MP5 was used in the electrolyte solution of Example 5-1. Evaluation was performed.

[Comparative Example 5-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 5-1, except that an electrolyte solution containing no MP5 was used in the electrolyte solution of Example 5-1, and the above evaluation was performed.
[Comparative Example 5-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 5-1, except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 5-1, and the above evaluation was performed. Carried out.

  From Table 5, when the non-aqueous electrolyte solution of Example 5-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the organic compound having a cyano group are not simultaneously added ( Compared to Comparative Example 5-1), the initial 0.5C efficiency does not decrease, and the recovery 0.05C efficiency after the high-temperature storage durability test is also excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 5-2), the initial 0.5C efficiency is lower than that of Comparative Example 5-1. Furthermore, the recovery 0.05C efficiency is lower than that of Comparative Example 5-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
When an organic compound having a cyano group is used alone (Comparative Example 5-3), the initial 0.5C efficiency is lower than that of Comparative Example 5-1. Further, the recovery 0.05C efficiency is improved as compared with Comparative Example 5-1, but the improvement effect is small and inferior to Example 5-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the organic compound having a cyano group, the battery characteristics are specifically improved by the synergistic effect.

<Example 6-1 and Comparative Examples 6-1 to 6-3>
[Example 6-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Further, 0.5% by mass of the compound (2-1) and 0.5% by mass of hexamethyldisilane (also referred to as “MP6”) were added as additives to the basic electrolytic solution, and Example 6-1 was added. A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Thereafter, CC-CV charge (0.05 C cut) to 4.4 V was performed at 0.2 C, and then discharged to 3.0 V at 1 C, which was defined as the initial 1 C capacity.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage endurance test was CC-CV charged to 0.05 V at a constant current of 0.2 C at 25 ° C. (0.05 C cut), and then to 3.0 V at 0.05 C. It was discharged again to recover 0.05 C capacity. Moreover, the ratio of the discharge capacity with respect to the charge capacity at this time was calculated | required, and this was made into recovery 0.05C efficiency (%).
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 6 as relative values when Comparative Example 6-1 is 100.0%. The same applies to the following.

[Comparative Example 6-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 6-1 except that the electrolyte solution containing no compound (2-1) and MP6 was used in the electrolyte solution of Example 6-1. Evaluation was performed.

[Comparative Example 6-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 6-1 except that an electrolyte solution containing no MP6 was used in the electrolyte solution of Example 6-1, and the above evaluation was performed.
[Comparative Example 6-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 6-1 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 6-1, and the above evaluation was performed. Carried out.

  From Table 6, when the non-aqueous electrolyte solution of Example 6-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the silicon-containing compound are not simultaneously added (Comparative Example 6). Compared to -1), the initial 1 C capacity is excellent, and the recovery 0.05 capacity and recovery 0.05 C efficiency after the high temperature storage durability test are also excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.

  In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 6-2), the initial 1C capacity is improved as compared with Comparative Example 6-1, but the improvement effect is small. Inferior to Example 6-1. Further, the recovery 0.05C capacity is improved as compared with Comparative Example 6-1, but is inferior to Example 6-1. Further, the recovery 0.05C efficiency is lower than that of Comparative Example 6-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.

When the silicon-containing compound is used alone (Comparative Example 6-3), the initial 1C capacity is improved as compared with Comparative Example 6-1, but the improvement effect is small and inferior to Example 6-1. Further, the recovery 0.05 C capacity is lower than that of Comparative Example 6-1. Further, the recovery 0.05C efficiency is improved as compared with Comparative Example 6-1, but the improvement effect is small and inferior to Example 6-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the silicon-containing compound.

<Example 7-1 and Comparative Examples 7-1 to 7-3>
[Example 7-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Furthermore, to this basic electrolyte solution, 0.5% by mass of the compound (2-1) and 0.5% by mass of lithium tetrafluoroborate (also referred to as “MP7”) were added as additives, and Example 7-1 A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05 C cut) to 4.4 V at 0.2 C, the battery was discharged again to 3.0 V at 0.2 C to stabilize the initial battery characteristics. Then, CC-CV charge (0.05 C cut) to 4.40 V at 0.2 C was performed, and then discharged to 3.0 V at 1 C, which was defined as the initial 1 C capacity.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high temperature storage endurance test is CC-CV charged to 0.05 V at a constant current of 0.2 C at 25 ° C. (0.05 C cut), and then to 3.0 V at 0.2 C. The battery was discharged again, the ratio of the discharge capacity to the charge capacity at this time was determined, and this was taken as the recovery 0.2C efficiency (%).

[Overcharge characteristics evaluation after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the battery characteristics evaluation after the high temperature storage durability test was CC-CV charged (0.05C cut) up to 4.4V at a constant current of 0.2C at 25 ° C. Thereafter, overcharging was performed at a constant current up to 5.0 V at 0.2 C at 45 ° C. Thereafter, the open circuit voltage (OCV) of the sufficiently cooled battery was measured, and this was regarded as OCV after overcharging.

Note that the OCV of the battery after the overcharge test mainly reflects the potential of the positive electrode. That is, when the OCV after overcharge is low, it indicates that the charge depth of the positive electrode is low. Normally, when the charging depth of the positive electrode is increased, metal elution and oxygen release from the positive electrode occur, which becomes the starting point of thermal runaway of the battery. Therefore, the battery safety at the time of overcharge can be ensured by lowering the OCV after overcharge.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, battery characteristic evaluation after high-temperature storage durability test, and overcharge characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 7 in terms of relative values when Comparative Example 7-1 is 100.0%. In addition, OCV after overcharge is shown by the difference from the comparative example 7-1. The same applies to the following.

[Comparative Example 7-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 7-1 except that the electrolyte solution containing no compound (2-1) and MP7 was used in the electrolyte solution of Example 7-1. Evaluation was performed.
[Comparative Example 7-2]
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 7-1 except that an electrolyte solution containing no MP7 was used in the electrolyte solution of Example 7-1, and the above evaluation was performed.

[Comparative Example 7-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 7-1 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 7-1, and the above evaluation was performed. Carried out.

From Table 7, when the non-aqueous electrolyte solution of Example 7-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the borate are not simultaneously added (Comparative Example 7). -1
), The initial 1 C capacity is excellent, and the recovery 0.2 C efficiency after the high temperature storage durability test is excellent. Moreover, since OCV after the overcharge after a high temperature storage durability test is low compared with the comparative example 7-1, it is excellent in safety | security. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics / safety after a high-temperature storage durability test.

  In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 7-2), the initial 1C capacity is improved as compared with Comparative Example 7-1, but the improvement effect is small. Compared to Example 7-1. Furthermore, although OCV after overcharge falls rather than the comparative example 7-1, it is inferior compared with the example 7-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.

When borate is used alone (Comparative Example 7-3), the initial 1C capacity is improved as compared with Comparative Example 7-1, but the improvement effect is small and inferior to Example 7-1. Further, the recovery 0.2C efficiency is lower than that of Comparative Example 7-1. Moreover, although OCV after overcharge falls rather than Comparative Example 7-1, it is inferior compared with Example 7-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the borate.

<Example 8-1 and Comparative Examples 8-1 to 8-3>
[Example 8-1]
[Preparation of non-aqueous electrolyte]
In a dry argon atmosphere, LiPF ₆ as an electrolyte is added to a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (also referred to as “DMC”). It was dissolved at a rate of 0.0 mol / L to obtain a basic electrolyte. Further, to this basic electrolyte solution, 0.5% by mass of the compound (2-1) and 0.5% by mass of 1,3-propane sultone (also referred to as “MP8”) were added as additives, and Example 8 was added. A non-aqueous electrolyte solution of -1 was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, the battery was discharged again to 3.0V at 0.2C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, discharge to 3.0V at 0.2C, and determine the ratio of the discharge capacity to the charge capacity at this time. The efficiency was 0.2C (%).

Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.
[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 4.2 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Overcharge characteristics evaluation after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage durability test was CC-CV charged (at 0.05 C cut) to 4.2 V at a constant current of 0.2 C at 25 ° C. and then immersed in an ethanol bath. The battery volume before overcharge was calculated from the buoyancy of the battery (Archimedes principle). Thereafter, overcharging was performed at a constant current of 0.5C to 45V at 45 ° C. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the amount of change from the battery volume before overcharge was defined as the amount of overcharge gas.

Note that the greater the amount of overcharged gas, the earlier the safety valve can be activated in a battery that activates the safety valve by detecting this when the internal pressure abnormally increases due to an abnormality such as overcharging. As a result, battery safety during overcharge can be ensured.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high temperature storage durability test, and overcharge characteristic evaluation after high temperature storage durability test were performed. The evaluation results are shown in Table 8 as relative values when Comparative Example 8-1 is taken as 100.0%. The same applies to the following.

[Comparative Example 8-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 8-1 except that the electrolyte solution containing no compound (2-1) and MP8 was used in the electrolyte solution of Example 8-1, and the above-mentioned Evaluation was performed.
[Comparative Example 8-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 8-1, except that an electrolyte solution containing no MP8 was used in the electrolyte solution of Example 8-1, and the above evaluation was performed.

[Comparative Example 8-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 8-1 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 8-1, and the above evaluation was performed. Carried out.

  From Table 8, when the non-aqueous electrolyte solution of Example 8-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the sulfur-containing organic compound are not added simultaneously (Comparative Example) Compared to 8-1), the initial 0.2C efficiency is excellent, and the amount of overcharge gas after the high-temperature storage durability test is large. That is, it is possible to provide a battery excellent in initial battery characteristics and evaluation of overcharge characteristics after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 8-2), the initial 0.2C efficiency is not different from that of Comparative Example 8-1. Furthermore, although the amount of overcharge gas increases rather than the comparative example 8-1, the improvement effect is small and is inferior compared with Example 8-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
In addition, when the sulfur-containing organic compound is used alone (Comparative Example 8-3), the initial 0.2C efficiency is higher than that of Comparative Example 8-1, but the improvement effect is small, compared with Example 8-1. Inferior. Furthermore, although the amount of overcharge gas increases rather than the comparative example 8-1, the improvement effect is small and is inferior compared with Example 8-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the sulfur-containing organic compound.

<Example 9-1 and Comparative Examples 9-1 to 9-6>
[Example 9-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.0 mol / L to a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Further, 0.5% by mass of the compound (2-1) and 0.5% by mass of ethyl propionate (also referred to as “MP9”) were added as additives to the basic electrolytic solution, and Example 9-1 was used. A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged and stabilized the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.4V at 0.2C, it discharged to 3.0V at 0.2C, and this was made into the initial 0.2C capacity | capacitance.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 2.4 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Overcharge characteristics evaluation after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage durability test was CC-CV charged (at 0.05 C cut) to 4.2 V at a constant current of 0.2 C at 25 ° C. and then immersed in an ethanol bath. The battery volume before overcharge was calculated from the buoyancy of the battery (Archimedes principle). Thereafter, overcharge was performed at a constant current of up to 5.0 V at 0.5 C at 45 ° C. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the amount of change from the battery volume before overcharge was defined as the amount of overcharge gas.

Note that the greater the amount of overcharged gas, the earlier the safety valve can be activated in a battery that activates the safety valve by detecting this when the internal pressure abnormally increases due to an abnormality such as overcharging. As a result, battery safety during overcharge can be ensured.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high temperature storage durability test, and overcharge characteristic evaluation after high temperature storage durability test were performed. The evaluation results are shown in Table 9 in terms of relative values when Comparative Example 9-1 is 100.0%. The same applies to the following.

[Example 9-2]
The electrolytic solution of Example 9-1 was the same as that of Example 9-1 except that 0.5% by mass of n-propyl propionate (also referred to as “MP9 ′”) was added instead of MP9. Thus, a non-aqueous electrolyte secondary battery was produced and the above evaluation was performed.
[Comparative Example 9-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 9-1 except that the electrolyte solution containing no compound (2-1) and MP9 was used in the electrolyte solution of Example 9-1. Evaluation was performed.

[Comparative Example 9-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 9-1 except that an electrolyte solution containing no MP9 was used in the electrolyte solution of Example 9-1, and the above evaluation was performed.
[Comparative Example 9-3]
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 9-1 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 9-1. Carried out.

[Comparative Example 9-4]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 9-2 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 9-2. Carried out.
[Comparative Example 9-5]
In the electrolytic solution of Example 9-1, a nonaqueous system was used in the same manner as in Example 9-1 except that an electrolytic solution to which 0.5% by mass of methyl propionate (also referred to as “MP”) was added instead of MP9 was used. An electrolyte secondary battery was prepared and evaluated as described above.

[Comparative Example 9-6]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Comparative Example 9-5 except that the electrolytic solution containing no compound (2-1) was used in the electrolytic solution of Comparative Example 9-5, and the above evaluation was performed. Carried out.

  From Table 9, when the non-aqueous electrolyte solution of Examples 9-1 to 9-2 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the carboxylic acid represented by the formula (2) Compared with the case where no ester is added simultaneously (Comparative Example 9-1), the initial 0.2C capacity is excellent, and the amount of overcharge gas after the high-temperature storage durability test is large. That is, it is possible to provide a battery excellent in initial battery characteristics and evaluation of overcharge characteristics after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 9-2), the initial 0.2 C capacity is lower than that of Comparative Example 9-1. Furthermore, the amount of overcharged gas is Comparative Example 9
Although it increases more than -1, the improvement effect is small and inferior to Examples 9-1 to 9-2. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
In addition, when the carboxylic acid ester represented by the formula (2) is used alone (Comparative Examples 9-3 to 9-4), the amount of overcharge gas is smaller than that of Comparative Example 9-1. It is clearly inferior to 9-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.

When an aromatic compound not included in the range of the carboxylic acid ester represented by the formula (2) and the aromatic carboxylic acid ester represented by the formula (1) were added simultaneously (Comparative Example 9-5), the initial stage The 0.2 C capacity is smaller than that of Comparative Example 9-1, which is clearly inferior to Examples 9-1 to 9-2. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this fact, the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the carboxylic acid ester represented by the formula (2). I can confirm.

<Example 10-1 and Comparative Examples 10-1 to 10-3>
[Example 10-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.0 mol / L to a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Furthermore, to this basic electrolyte solution, 0.5% by mass of compound (2-1) and 0.5% by mass of lithium difluorophosphate (also referred to as “MP10”) were added as additives, and Example 10-1 A non-aqueous electrolyte solution was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). Thereafter, in a state of being pressed by being sandwiched between glass plates, a constant current charge was performed at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then a constant current discharge was performed to 0.2 V at 0.2 C. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, the battery was discharged again to 3.0V at 0.2C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, the volume is measured by immersing the non-aqueous electrolyte secondary battery in an ethanol bath, and the change from the initial battery volume is calculated. The initial gas amount was used.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 4.2 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Overcharge characteristics evaluation after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage durability test was CC-CV charged (at 0.05 C cut) to 4.2 V at a constant current of 0.2 C at 25 ° C. and then immersed in an ethanol bath. The battery volume before overcharge was calculated from the buoyancy of the battery (Archimedes principle). Thereafter, overcharging was performed at a constant current of 0.5C to 45V at 45 ° C. The sufficiently cooled battery was immersed in an ethanol bath to measure the volume, and the amount of change from the battery volume before overcharge was defined as the amount of overcharge gas.

Note that the greater the amount of overcharged gas, the earlier the safety valve can be activated in a battery that activates the safety valve by detecting this when the internal pressure abnormally increases due to an abnormality such as overcharging. As a result, battery safety during overcharge can be ensured.
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high temperature storage durability test, and overcharge characteristic evaluation after high temperature storage durability test were performed. The evaluation results are shown in Table 10 as relative values when Comparative Example 10-1 is 100.0%. The same applies to the following.

[Comparative Example 10-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 10-1, except that the electrolyte solution containing no compound (2-1) and MP10 was used in the electrolyte solution of Example 10-1. Evaluation was performed.
[Comparative Example 10-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 10-1, except that an electrolyte solution containing no MP10 was used in the electrolyte solution of Example 10-1, and the above evaluation was performed.

[Comparative Example 10-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 10-1, except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 10-1. Carried out.

  From Table 10, when the non-aqueous electrolyte solution of Example 10-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and lithium difluorophosphate are not added simultaneously (Comparative Example). Compared to 10-1), the initial gas amount is small, and the amount of overcharged gas after the high-temperature storage durability test is large. That is, it is possible to provide a battery excellent in initial battery characteristics and evaluation of overcharge characteristics after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by the formula (1) is used alone (Comparative Example 10-2), the initial gas amount is increased as compared with Comparative Example 10-1. Furthermore, although the amount of overcharge gas increases rather than the comparative example 10-1, the improvement effect is small and is inferior compared with Example 10-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
In addition, when lithium difluorophosphate is used alone (Comparative Example 10-3), the initial gas amount is smaller than that of Comparative Example 10-1, but the improvement effect is small and inferior to Example 10-1. . Furthermore, the amount of overcharged gas is smaller than that of Comparative Example 10-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and lithium difluorophosphate, the battery characteristics are specifically improved by the synergistic effect.

<Example 11-1 and Comparative Examples 11-1 to 11-3>
[Example 11-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.0 mol / L to a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). It was made to melt | dissolve in the ratio and used as the basic electrolyte solution. Furthermore, Example 11 was prepared by adding 0.5% by mass of the compound (2-1) and 0.5% by mass of lithium bis (oxalato) borate (also referred to as “MP11”) to the basic electrolyte. A non-aqueous electrolyte solution of -1 was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
The non-aqueous electrolyte secondary battery was immersed in an ethanol bath, and the initial battery volume was determined from the buoyancy at that time (Archimedes principle). Thereafter, in a state of being pressed by being sandwiched between glass plates, a constant current charge was performed at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then a constant current discharge was performed to 0.2 V at 0.2 C. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05C cut) to 4.1V with a current corresponding to 0.2C, it reaches 3.0V with a constant current of 0.2C. Discharged. Next, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, the battery was discharged again to 3.0V at 0.2C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, discharge to 3.0V at 0.2C, and determine the ratio of the discharge capacity to the charge capacity at this time. The efficiency was 0.2C (%). Then, after CC-CV charge (0.05C cut) to 4.2V at 0.2C, the volume is measured by immersing the non-aqueous electrolyte secondary battery in an ethanol bath, and the change from the initial battery volume is calculated. The initial gas amount was used.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) to 4.2 V at 0.2 C at 25 ° C., and then at 85 ° C. for 1 day. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage endurance test is CC-CV charged to 0.05 V at a constant current of 0.2 C at 25 ° C. (0.05 C cut), and then to 3.0 V at 0.2 C. The battery was discharged again, the ratio of the discharge capacity to the charge capacity at this time was determined, and this was taken as the recovery 0.2C efficiency (%).
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 11 in terms of relative values when Comparative Example 11-1 is 100.0%. The same applies to the following.

[Comparative Example 11-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 11-1, except that the electrolyte solution containing no compound (2-1) and MP11 was used in the electrolyte solution of Example 11-1. Evaluation was performed.

[Comparative Example 11-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 11-1, except that an electrolyte solution containing no MP11 was used in the electrolyte solution of Example 11-1, and the above evaluation was performed.
[Comparative Example 11-3]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 11-1, except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 11-1, and the above evaluation was performed. Carried out.

  From Table 11, when the non-aqueous electrolyte solution of Example 11-1 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the oxalate are not simultaneously added (Comparative Example 11). Compared to -1), the initial 0.2C efficiency is excellent, and the recovery 0.2C efficiency after the high temperature storage durability test is excellent. That is, it is possible to provide a battery excellent in initial battery characteristics and battery characteristics evaluation after a high-temperature storage durability test.

In addition, when the aromatic carboxylic acid ester represented by Formula (1) is used independently (Comparative Example 11-2), the initial 0.2C efficiency is not different from that of Comparative Example 11-1. Further, the recovery 0.2C efficiency is not different from that of Comparative Example 11-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
When oxalate is used alone (Comparative Example 11-3), the initial 0.2C efficiency is not different from that of Comparative Example 11-1. Further, the recovery 0.2C efficiency is not different from that of Comparative Example 11-1. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the oxalate.

<Examples 12-1 to 12-2 and Comparative Examples 12-1 to 12-4>
[Example 12-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio. Then, 5.0% by mass of monofluoroethylene carbonate (MP2) as an additive was dissolved to obtain a basic electrolytic solution. Furthermore, 1.0 mass% of compound (2-1) was added, and the non-aqueous electrolyte solution of Example 12-1 was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied on both sides of a 15 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 10 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The above positive electrode, negative electrode, and polypropylene separator were laminated in the order of the negative electrode, separator, positive electrode, separator, and negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05 C cut) to 4.1 V with a current corresponding to 0.2 C, it was left under conditions of 45 ° C. and 72 hours. . Then, it discharged to 3.0V with a constant current of 0.2C. Next, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, the battery was discharged again to 3.0V at 0.2C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, it discharged to 3.0V at 0.2C, and this was made into the initial 0.2C capacity | capacitance. Furthermore, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, it discharged to 3.0V at 0.5C, and this was made into the initial 0.5C capacity | capacitance. Then, the ratio of the initial 0.5C capacity to the initial 0.2C capacity was determined, and this was used as the initial rate characteristic (%).
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) at 25 ° C. to 4.35 V at 0.2 C, and then at 60 ° C. for 7 days. And stored at high temperature. After the battery was sufficiently cooled, it was discharged to 3.0 V at 0.2 C at 25 ° C.

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high temperature storage endurance test is CC-CV charged (0.05C cut) to 4.35V at a constant current of 0.2C at 25 ° C, and then to 3.0V at 0.2C. It was discharged again, and this was set to a recovery 0.2 C capacity. Furthermore, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, it discharged to 3.0V at 0.5C, and this was set as the recovery 0.5C capacity. Then, the ratio of the recovery 0.5 C capacity to the recovery 0.2 C capacity was determined, and this was defined as the post-storage rate characteristic (%).
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 12 as relative values when the value of Comparative Example 12-1 is 100.0%. The same applies to the following.

[Example 12-2]
The above evaluation was performed except that the electrolyte solution of Example 12-1 was further added with 3.0 mass% of 1-phenyl-1,3,3-trimethylindane (also referred to as “MP12”). did.

[Comparative Example 12-1]
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 12-1, except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 12-1. Carried out.
[Comparative Example 12-2]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 12-2 except that the electrolyte solution containing no compound (2-1) was used in the electrolyte solution of Example 12-2. Carried out.

[Comparative Example 12-3]
A nonaqueous electrolyte secondary battery in the same manner as in Example 12-1, except that 1.0% by mass of the compound (3-1) was used instead of the compound (2-1) in the electrolyte solution of Example 12-1. And the above evaluation was performed.
[Comparative Example 12-4]
A nonaqueous electrolyte secondary battery in the same manner as in Example 12-2 except that 1.0% by mass of the compound (3-1) was used instead of the compound (2-1) in the electrolytic solution of Example 12-2. And the above evaluation was performed.

From Table 12, when the nonaqueous electrolytic solution of Example 12-1 according to the present invention is used, the initial rate characteristics are excellent compared to the case where the fluorine-containing cyclic carbonate is used alone (Comparative Example 12-1). In addition, the rate characteristics after storage after the high temperature storage durability test are also excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.
Furthermore, when the non-aqueous electrolyte solution of Example 12-2 according to the present invention is used, the aromatic carboxylic acid ester represented by the formula (1) and the aromatic compound other than the formula (1) are not simultaneously added. Compared to (Comparative Example 12-1), the initial rate characteristics are excellent, and the post-storage rate characteristics after the high-temperature storage endurance test are also excellent. Moreover, the improvement effect is superior to Example 12-1. That is, it is possible to provide a battery that is further excellent in initial battery characteristics and battery characteristics after a high-temperature storage durability test.

  In addition, when an aromatic compound other than Formula (1) and a fluorine-containing cyclic carbonate are added simultaneously (Comparative Example 12-2), the initial rate characteristics are lower than those of Comparative Example 12-1. Further, the post-storage rate characteristic is improved as compared with Comparative Example 12-1, but the improvement effect is small and inferior to Example 12-2. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.

When an aromatic compound not included in the range of the aromatic carboxylic acid ester represented by the formula (1) is used at the same time as the aromatic compound other than the fluorine-containing cyclic carbonate and the formula (1) (Comparative Example 12-3 ), The initial rate characteristic is improved as compared with Comparative Example 12-1, but the rate characteristic after storage is lowered. Therefore, it is clear that the battery using the electrolytic solution according to the present invention has superior characteristics.
From this, it can be confirmed that the battery characteristics are specifically improved by the synergistic effect by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the aromatic compound other than the formula (1). .

<Example 13-1 and Comparative Example 13-1>
[Example 13-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio. Then, 5.0% by mass of monofluoroethylene carbonate (MP2) as an additive was dissolved to obtain a basic electrolytic solution. Furthermore, the non-aqueous electrolyte solution of Example 13-1 was prepared by adding 3.0% by mass of the compound (2-2).

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied to both sides of a 21 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 12 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, the positive electrode, the separator, and the negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after a constant current-constant voltage charge (also referred to as “CC-CV charge”) (0.05 C cut) to 4.1 V with a current corresponding to 0.2 C, it was left under conditions of 45 ° C. and 72 hours. . Then, it discharged to 3.0V with a constant current of 0.2C. Next, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, the battery was discharged again to 3.0V at 0.2C to stabilize the initial battery characteristics. Then, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, it discharged to 3.0V at 0.2C, and this was made into the initial 0.2C capacity | capacitance.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) at 25 ° C. to 4.35 V, and then immersed in an ethanol bath. The battery volume before the high temperature storage endurance test was determined from the buoyancy. (Principle of Archimedes) Thereafter, high temperature storage was carried out at 60 ° C. for 7 days. After sufficiently cooling the battery, the volume was measured by immersion in an ethanol bath, and the amount of storage gas was determined from the volume change before and after the high temperature storage durability test. Next, it was discharged to 3.0 V at 0.2 C at 25 ° C., the capacity remaining after the high temperature storage endurance test was measured, the ratio to the initial 0.2 C capacity was determined, and this was defined as the residual ratio (%) .

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high temperature storage endurance test is CC-CV charged (0.05C cut) to 4.35V at a constant current of 0.2C at 25 ° C, and then to 3.0V at 0.2C. The battery was discharged again, the ratio of the discharge capacity to the charge capacity at this time was determined, and this was taken as the recovery 0.2C efficiency (%).
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 13 as relative values when Comparative Example 13-1 is 100.0%. The same applies to the following.

[Comparative Example 13-1]
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 13-1, except that the electrolyte solution containing no compound (2-2) was used in the electrolyte solution of Example 13-1, and the above evaluation was performed. Carried out.

From Table 13, when the non-aqueous electrolyte solution of Example 13-1 according to the present invention is used, the initial 0.2 C capacity is excellent as compared with the case where the fluorine-containing cyclic carbonate is used alone (Comparative Example 13-1). In addition, the storage gas amount, the residual ratio, and the recovery 0.2C efficiency after the high temperature storage durability test are excellent. That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.
From this, it can be confirmed that by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the fluorine-containing cyclic carbonate, the battery characteristics are specifically improved by the synergistic effect.

<Example 14-1 and Comparative Example 14-1>
[Example 14-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere, LiPF ₆ as an electrolyte was added at 1.2 mol / L in a mixed solvent (mixing volume ratio 3: 4: 3) composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). It was made to melt | dissolve in the ratio. Then, 5.0 mass% of monofluoroethylene carbonate (MP2), 2.0 mass% of 1,3-propane sultone (MP8) and 3.0 mass% of adiponitrile (MP5) are dissolved as additives to obtain a basic electrolyte solution. did. Furthermore, 2.0 mass% of compound (2-2) was added, and the non-aqueous electrolyte solution of Example 14-1 was prepared.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied to both sides of a 21 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of negative electrode]
Natural graphite powder as negative electrode active material, aqueous dispersion of sodium carboxymethylcellulose as thickener (carboxymethylcellulose sodium concentration 1 mass%), aqueous dispersion of styrene butadiene rubber as binder (concentration of styrene butadiene rubber 50 mass%) ) And mixed with a disperser to form a slurry. This slurry was uniformly applied to one side of a 12 μm thick copper foil, dried, and then pressed to obtain a negative electrode. In addition, in the negative electrode after drying, it produced so that it might become the mass ratio of natural graphite: carboxymethylcellulose sodium: styrene-butadiene rubber = 98: 1: 1.

[Production of secondary battery]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, the positive electrode, the separator, and the negative electrode to produce a battery element. After inserting this battery element into a bag made of a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of initial battery characteristics]
In a state where a nonaqueous electrolyte secondary battery is sandwiched between glass plates and pressurized, the battery is charged with a constant current at 25 ° C. for 6 hours at a current corresponding to 0.05 C, and then discharged to 3.0 V at 0.2 C. Went. Furthermore, after carrying out constant current-constant voltage charge "CC-CV charge" (0.05C cut) to 4.1V with the electric current equivalent to 0.2C, it was left to stand on 45 degreeC and 72 hours conditions. Then, it discharged to 3V with a constant current of 0.2C. Next, after CC-CV charge (0.05C cut) to 4.35V at 0.2C, the battery was discharged again to 3V at 0.2C to stabilize the initial battery characteristics. Then, after CCCV charge (0.05C cut) to 4.35V at 0.2C, it discharged to 3V at 0.2C, and this was made into initial 0.2C capacity.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.

[High temperature storage durability test]
After the initial battery characteristics evaluation, the non-aqueous electrolyte secondary battery was subjected to CC-CV charge (0.05 C cut) at 25 ° C. to 4.35 V at 0.2 C, and then at 60 ° C. for 7 days. And stored at high temperature. After sufficiently cooling the battery, it was discharged to 3 V at 0.2 C at 25 ° C., the remaining capacity was measured after the high-temperature storage durability test, and the ratio to the initial 0.2 C capacity was obtained. %).

[Evaluation of battery characteristics after high temperature storage durability test]
The non-aqueous electrolyte secondary battery after the high-temperature storage endurance test was CCCV charged (cut by 0.05 C) to 4.35 V at a constant current of 0.2 C at 25 ° C., and then discharged again to 3 V at 0.2 C. The battery capacity after the high temperature storage endurance test was measured, the ratio to the initial 0.2 C capacity was determined, and this was defined as the recovery rate (%).
Using the produced non-aqueous electrolyte secondary battery, initial battery characteristic evaluation, high-temperature storage durability test, and battery characteristic evaluation after high-temperature storage durability test were performed. The evaluation results are shown in Table 14 as relative values when the value of Comparative Example 14-1 is 100.0%. The same applies to the following.

[Comparative Example 14-1]
A nonaqueous electrolyte secondary battery in the same manner as in Example 14-1, except that 2.4% by mass of the compound (3-1) was used instead of the compound (2-2) in the electrolytic solution of Example 14-1. And the above evaluation was performed.
In addition, the compound (2-2) added in Example 14-1 and the compound (3-1) added in Comparative Example 14-1 are equal amounts of substances.

  From Table 14, when the non-aqueous electrolyte solution of Example 14-1 according to the present invention is used, an aromatic compound not included in the range of the aromatic carboxylic acid ester represented by the formula (1), a fluorine-containing cyclic carbonate, Compared to the case where a sulfur-containing organic compound and an organic compound having a cyano group are used simultaneously (Comparative Example 14-1), the initial 0.2 C capacity is excellent, and the residual rate and the recovery rate after a high-temperature storage durability test are excellent. . That is, it is possible to provide a battery having excellent initial battery characteristics and battery characteristics after a high-temperature storage durability test.

  Thus, by simultaneously using the aromatic carboxylic acid ester represented by the formula (1) and the fluorine-containing cyclic carbonate, the sulfur-containing organic compound or the organic compound having a cyano group, the battery characteristics are specifically determined by the synergistic effect. It can be confirmed that it is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the non-aqueous electrolyte solution which can bring about the non-aqueous electrolyte secondary battery excellent in the initial battery characteristic and the battery characteristic after an endurance test can be provided, and a non-aqueous electrolyte secondary battery can be provided. Can be reduced in size, performance and safety. The non-aqueous electrolyte solution and non-aqueous electrolyte secondary battery of the present invention can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, and transceivers. , Electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, motor, automobile, motorcycle, motorbike, bicycle, lighting equipment, toy, game equipment, clock, electric tool, strobe, camera, load leveling Power supply, natural energy storage power supply, lithium ion capacitor, and the like.

Claims (6)

A non-aqueous electrolyte solution for a non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of occluding and releasing metal ions, the non-aqueous electrolyte solution together with an electrolyte and a non-aqueous solvent,
(I) Formula (1):

(Where
A ² is an aryl group which may have a substituent,
n ² is an integer of 1 or 2,
a ² is an integer of 1 or 2,
When a ² is 1, R ⁴ is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an aryl group which may have a substituent, However, when n ² is 2, R ⁴ is an aryl group which may have a substituent,
when a ² is 2, R ⁴ is a single bond, an aliphatic hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an arylene group which may have a substituent; A plurality of A ² may be the same or different, provided that when n ² is 2, R ⁴ is an arylene group which may have a substituent)
An aromatic carboxylic acid ester represented by:
(II) Fluorine-containing cyclic carbonate, sulfur-containing organic compound, phosphonic acid ester, organic compound having cyano group, organic compound having isocyanate group, silicon-containing compound, aromatic compound other than formula (1), formula (2):

Where
R ⁵ is a hydrocarbon group having 1 to 4 carbon atoms,
R ⁶ is a carboxylic acid ester represented by being an ethyl group, an n-propyl group or an n-butyl group, a cyclic compound having a plurality of ether bonds, a monofluorophosphate, a difluorophosphate, a borate, A non-aqueous electrolyte containing at least one compound selected from the group consisting of oxalates and fluorosulfonates. The non-aqueous electrolyte solution according to claim 1, wherein a ² is 1 in the formula (1). The non-aqueous electrolyte solution according to claim 1 or 2, wherein A ² in the formula (1) is a phenyl group.   The said non-aqueous electrolyte solution contains 0.001 mass% or more and 10 mass% or less of aromatic carboxylic acid ester represented by the said Formula (1). Non-aqueous electrolyte.   The non-aqueous electrolyte is a fluorine-containing cyclic carbonate, a sulfur-containing organic compound, a phosphonic acid ester, an organic compound having a cyano group, an organic compound having an isocyanate group, a silicon-containing compound, an aromatic compound other than the formula (1), Selected from the group consisting of the carboxylic acid ester represented by the formula (2), a cyclic compound having a plurality of ether bonds, monofluorophosphate, difluorophosphate, borate, oxalate and fluorosulfonate The non-aqueous electrolyte solution of any one of Claims 1-4 which contains at least 1 sort (s) of compound by 0.001 mass% or more and 20 mass% or less.   A non-aqueous electrolyte secondary battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte is any one of claims 1 to 5. A non-aqueous electrolyte secondary battery comprising the non-aqueous electrolyte solution according to claim 1.