TW201622226A - Organic electrolyte and organic electrolyte battery - Google Patents

Abstract

The present invention provides an organic electrolyte capable of improving the initial charge capacity of an organic electrolyte battery which influences the maximum traveling distance of an electric vehicle, the organic electrolyte comprising an organic solvent formed from a high-permittivity solvent and a low-viscosity solvent, and a compound such as 1,1-dicyclohexylethane, a derivative thereof or hydrindane, wherein the low-viscosity solvent is diethyl carbonate and/or ethyl methyl carbonate, and the proportion of the low-viscosity solvent in the organic solvent is at least 70% by volume.

Description

Organic electrolyte and organic electrolyte battery

The present invention relates to an organic electrolyte and an organic electrolyte storage battery using the same.

In recent years, in an attempt to construct a society that is in harmony with the global environment, there have been many attempts to curb CO ₂ emissions caused by the use of fossil fuels. In particular, the CO ₂ emissions in the transportation part of automobiles have been standardized by the government, and the hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and battery-driven electric vehicles carried out by various automobile companies. The development and commercialization of the vehicle (BEV) is accelerating. As an energy source for such electric vehicles, the development of large-sized batteries capable of stably charging and discharging for a long period of time has been vigorously carried out. Compared with other batteries including nickel-hydrogen batteries, organic-based electrolyte batteries have high operating voltages, and are powerful batteries that are easy to achieve high output and high energy density. As an energy source for electric vehicles, the importance is increased. For this reason, various developments have continued, and for example, compounds for increasing the initial storage capacity that affect the travelable distance of an electric vehicle have been discussed. The inventors have also studied various compounds, and as a result, it has been found that a compound having a cyclohexyl group increases the initial storage capacity (Patent Document 1). On the other hand, in automotive applications, the initial storage capacity is required, and at the same time, it is required to be used for up to about 10 years, that is, high durability. For example, it is reported in Non-Patent Document 1 that when a saturated hydrocarbon compound such as decalin is added to an electrolyte according to an electric conduction experiment using a lithium-indium alloy electrode, formation of dendritic lithium on the alloy electrode is suppressed. Although this report teaches the deterioration suppressing effect of a secondary battery using a lithium metal negative electrode, the detailed experimental contents are also unclear, and it is not clear whether it can be applied to an actual battery. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] International Publication 2013/094603 [Non-Patent Document]

[Non-Patent Document 1] Journal of Power Sources, Vol. 20, pp. 253-258

[Problems to be solved by the invention]

The object of the present invention is to improve the long-term durability of an organic electrolyte battery. [Means for solving the problem]

As a result of intensive investigations on the above-mentioned problems, the inventors of the present invention found that by including a compound containing a cyclohexyl group in an organic electrolyte, durability is improved, and it has been found that the type of the low-viscosity solvent contained in the organic electrolyte is adjusted. And the blending amount can further improve the durability, and finally complete the present invention.

In other words, the present invention relates to an organic electrolyte comprising an organic solvent composed of a high dielectric constant solvent and a low viscosity solvent, and a compound represented by any one of the following formulas (1) to (4). The low-viscosity solvent is diethyl carbonate and/or ethyl methyl carbonate, and the ratio of the low-viscosity solvent in the organic solvent is 70% by volume or more. 【化1】 (In the formula (1), R ₁ to R ₁₁ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or Halogen, R ₁₂ to R ₁₃ are a hydrogen atom, "methyl, ethyl or halogen-containing methyl, ethyl" or halogen, and R ₁₄ is an unsubstituted or substituted cyclohexyl group having a maximum number of substituents of 11, Each is independently a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkyl group having 1 to 4 carbon atoms containing halogen, or a halogen. (In the formula (2), R ₁ to R ₁₁ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, Or halogen, R ₁₂ is a linear alkyl group having a carbon number of 3 or 4, and a part of hydrogen may be substituted with a halogen and/or a "methyl or halogen-containing methyl group". R ₁₃ is unsubstituted or substituted. a cyclohexyl group having a maximum number of substituents of 11, and each independently being a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or a halogen. 3] (In the formula (3), R ₁ to R ₁₄ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or Halogen.) [Chemical 4] (In the formula (4), R ₁ to R ₁₆ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or halogen.)

Further, the present invention relates to an organic electrolyte storage battery using the organic electrolyte. [Effects of the Invention]

By using the organic electrolyte of the present invention, the durability of the battery can be improved. Therefore, when the electric vehicle is equipped with the storage battery using the organic electrolyte of the present invention, deterioration due to repeated charge and discharge over a long period of time can be suppressed, and the service life of the electric vehicle can be prolonged. Moreover, due to this high durability, it is possible to charge at a relatively high voltage.

Hereinafter, the present invention will be described in detail.

The organic electrolyte of the present invention contains a compound represented by any one of the following formulas (1) to (4).

【化5】

In the formula (1), R ₁ to R ₁₁ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or a halogen. R ₁₂ R R ₁₃ are a hydrogen atom, a "methyl, ethyl or halogen-containing methyl group, an ethyl group" or a halogen, and R ₁₄ is an unsubstituted or substituted cyclohexyl group having a maximum number of substituents of 11, and each It is a linear or branched alkyl group having a carbon number of 1 to 4, a linear or branched alkyl group having a halogen number of 1 to 4, or a halogen.

【化6】

In the formula (2), R ₁ to R ₁₁ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or Halogen, R ₁₂ is a linear alkyl group having a carbon number of 3 or 4, and a part of hydrogen may be substituted with a halogen and/or a "methyl or halogen-containing methyl group". R ₁₃ is an unsubstituted or substituted cyclohexyl group having a maximum number of substituents of 11, and each independently is a linear or branched alkyl group having 1 to 4 carbon atoms, or a linear or branched halogen having 1 to 4 carbon atoms; Alkyl, or halogen.

【化7】

In the formula (3), R ₁ to R ₁₄ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or a halogen. .

【化8】

In the formula (4), R ₁ to R ₁₆ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or a halogen. .

Specific examples of the compound represented by any one of the formulas (1) to (4) include cyclohexyl (3,4-dimethylcyclohexyl)methane and 1-cyclohexyl-1-( 3,4-Dimethylcyclohexyl)ethane, 2-(3,4-dimethylcyclohexyl)-2-cyclohexylpropane, cyclohexyl (2,4-dimethylcyclohexyl)methane, 1- Cyclohexyl-1-(2,4-dimethylcyclohexyl)ethane, 2-(2,4-dimethylcyclohexyl)-2-cyclohexylpropane, cyclohexyl (2,5-dimethylcyclo) Hexyl)methane, 1-cyclohexyl-1-(2,5-dimethylcyclohexyl)ethane, 2-(2,5-dimethylcyclohexyl)-2-cyclohexylpropane, cyclohexyl (2- Ethylcyclohexyl)methane, 1-cyclohexyl-1-(2-ethylcyclohexyl)ethane, 2-cyclohexyl-2-(2-ethylcyclohexyl)propane, cyclohexyl (3-ethylcyclo) Hexyl)methane, 1-cyclohexyl-1-(3-ethylcyclohexyl)ethane, 2-cyclohexyl-2-(3-ethylcyclohexyl)propane, cyclohexyl (4-ethylcyclohexyl)methane , 1-cyclohexyl-1-(4-ethylcyclohexyl)ethane, 2-cyclohexyl-2-(4-ethylcyclohexyl)propane, cyclohexyl (2-methylcyclohexyl)methane, 1- Cyclohexyl-1-(2-methylcyclohexyl)ethane, cyclohexyl (3-methylcyclohexyl)methane, 1-cyclohexyl-1-(3-methylcyclohexane Ethylene, 2-cyclohexyl-2-(3-methylcyclohexyl)propane, cyclohexyl (4-methylcyclohexyl)methane, 1-cyclohexyl-1-(4-methylcyclohexyl)ethane , (2-methylcyclohexyl)(4-methylcyclohexyl)methane, 1-(2-methylcyclohexyl)-1-(4-methylcyclohexyl)ethane, 2-(2-methyl Cyclohexyl)-2-(4-methylcyclohexyl)propane, (2-methylcyclohexyl)(3-methylcyclohexyl)methane, 1-(2-methylcyclohexyl)-1-(3- Methylcyclohexyl)ethane, 2-(2-methylcyclohexyl)-2-(3-methylcyclohexyl)propane, (4-methylcyclohexyl)(3-methylcyclohexyl)methane, 1 -(4-methylcyclohexyl)-1-(3-methylcyclohexyl)ethane, 2-(4-methylcyclohexyl)-2-(3-methylcyclohexyl)propane, cyclohexyl (4 -isobutylphenyl)methane, cyclohexyl (4-isobutylcyclohexyl)methane, 1-cyclohexyl-1-(4-isobutylcyclohexyl)ethane, 2-cyclohexyl-2-(4 -isobutylcyclohexyl)propane, cyclohexyl (2-isobutylcyclohexyl)methane, 1-cyclohexyl-1-(2-isobutylcyclohexyl)ethane, 2-cyclohexyl-2-(2 -isobutylcyclohexyl)propane, cyclohexyl (3-isobutylcyclohexyl)methane, 1-cyclohexyl-1-(3-isobutylcyclohexyl)ethane, 2-cyclohexyl-2-(3 -isobutylcyclohexene Propane, cyclohexyl (4-isopropylphenyl)methane, cyclohexyl (4-isopropylcyclohexyl)methane, 1-cyclohexyl-1-(4-isopropylcyclohexyl)ethane, 2- Cyclohexyl-2-(4-isopropylcyclohexyl)propane, cyclohexyl (2-isopropylcyclohexyl)methane, 1-cyclohexyl-1-(2-isopropylcyclohexyl)ethane, 2- Cyclohexyl-2-(2-isopropylcyclohexyl)propane, 2-cyclohexyl-2-(2-isopropylcyclohexyl)propane, cyclohexyl (3-isopropylcyclohexyl)methane, 1-ring Hexyl-1-(3-isopropylcyclohexyl)ethane, 2-cyclohexyl-2-(3-isopropylcyclohexyl)propane, 2,2-dicyclohexylbutane, 1,3-bicyclo Hexetane, 1,4-dicyclohexylbutane, 1,1-dicyclohexyl-2-methylpropane, dicyclohexylmethane, 1,1-dicyclohexylethane, 2,2-dicyclohexyl Propane, bis(4-methylcyclohexyl)methane, 1,1-bis(4-methylcyclohexyl)ethane, 1,1-bis(2-methylcyclohexyl)ethane, 1,1-double (3-methylcyclohexyl)ethane, 1,1-bis(4-ethylcyclohexyl)ethane, 1,1-bis(2-ethylcyclohexyl)ethane, 1,1-double (3 -ethylcyclohexyl)ethane, 1,1-bis(4-(isopropylcyclohexyl))ethane, 1,1-bis(2-(isopropylcyclohexyl))ethane, 1,1 - double (3- (different Cyclohexyl)) ethane, 1,1-bis(3,4-dimethylcyclohexyl)ethane, 1,1-bis(3,5-dimethylcyclohexyl)ethane, 1,1- Bis(2,5-dimethylcyclohexyl)ethane, 1,1-bis(3,4,5-trimethylcyclohexyl)ethane, 1,1-bis(3-fluorocyclohexyl)ethane 1,1-bis(2,5-difluorocyclohexyl)ethane, 1,1-bis(3,5-difluorocyclohexyl)ethane, 1,1-bis(2,4-difluorocyclo Hexyl)ethane, 1,1-bis(3,4,5-trifluorocyclohexyl)ethane, bis(4-methylcyclohexyl)methane, bis(2-methylcyclohexyl)methane, bis (3) -Methylcyclohexyl)methane, bis(4-ethylcyclohexyl)methane, bis(2-ethylcyclohexyl)methane, bis(3-ethylcyclohexyl)methane, bis(4-isopropylcyclohexyl) )) methane, bis(2-isopropylcyclohexyl))methane, bis(3-isopropylcyclohexyl))methane, bis(3,4-dimethylcyclohexyl)methane, bis(3,5- Dimethylcyclohexyl)methane, bis(2,5-dimethylcyclohexyl)methane, bis(3,4,5-trimethylcyclohexyl)methane, bis(3-fluorocyclohexyl)methane, bis ( 2,5-Difluorocyclohexyl)methane, bis(3,4-difluorocyclohexyl)methane, bis(3,5-difluorocyclohexyl)methane, bis(3,4,5-trifluorocyclohexyl) Methane, 2,2-bis(4-methylcyclohexyl)propane , 2,2-bis(2-methylcyclohexyl)propane, 2,2-bis(3-methylcyclohexyl)propane, 2,2-bis(4-ethylcyclohexyl)propane, 2,2- Bis(2-ethylcyclohexyl)propane, 2,2-bis(3-ethylcyclohexyl)propane, 2,2-bis(4-isopropylphenyl)propane, 2,2-bis(2- Isopropylphenyl)propane, 2,2-bis(3-isopropylphenyl)propane, 2,2-bis(3,4-dimethylcyclohexyl)propane, 2,2-bis (3, 5-dimethylcyclohexyl)propane, 2,2-bis(2,5-dimethylcyclohexyl)propane, 2,2-bis(3,4,5-trimethylcyclohexyl)propane, 2, 2-bis(3-fluorocyclohexyl)propane, 2,2-bis(2,5-difluorocyclohexyl)propane, 2,2-bis(3,4-difluorocyclohexyl)propane, 2,2- Bis(3,5-difluorocyclohexyl)propane, trans octahydroindole, cis octahydroquinone, and the like. These may be used alone or in combination of two or more.

Among these, especially 1,1-dicyclohexylethane, 1-cyclohexyl-1-(2,5-dimethylcyclohexyl)ethane, 1-cyclohexyl-1-(2,3- Dimethylcyclohexyl)ethane, 1-cyclohexyl-1-(2,4-dimethylcyclohexyl)ethane, 1-cyclohexyl-1-(4-ethylcyclohexyl)ethane, 1, 3-dicyclohexylpropane, 1,4-dicyclohexylbutane, 1,3-dicyclohexylbutane, trans octahydroindole, cis octahydroquinone, 1,1-dicyclohexylethane It is particularly preferred that 1-cyclohexyl-1-(2,5-dimethylcyclohexyl)ethane, trans octahydroindole, and cis octahydroindole are preferred.

The blending ratio of the compound represented by any one of the formulas (1) to (4) is preferably 0.05% by weight or more, and more preferably 0.1% by weight or more, based on the organic electrolyte. On the other hand, it is preferably 10% by weight or less, more preferably 5% by weight or less. When the blending ratio of the compound represented by the formula (1) is less than 0.05% by weight, the effect according to the present invention may not be obtained; if it is more than 10% by weight, the solubility of the electrolyte salt may be lowered, or the organic electrolyte may be The viscosity increases and the performance of the battery deteriorates.

Further, the purity of the compound represented by any one of the formulae (1) to (4) is preferably 95% or more, more preferably 96% or more, and still more preferably 97% or more. When the purity is lower than 95%, impurities which hinder the effects of the present invention may be contained, and the original effect may not be obtained.

The organic-based electrolyte of the present invention is mainly composed of a compound represented by any one of the formulae (1) to (4), an organic solvent, and an electrolyte salt, and a high dielectric constant solvent and a low-viscosity solvent are used as the organic solvent.

The content ratio of the high dielectric constant solvent in the organic solvent is preferably from 5 to 30% by volume, more preferably from 10 to 25% by volume, and still more preferably from 15 to 25% by volume. On the other hand, the content ratio of the low viscosity solvent in the organic electrolyte is preferably 70 to 95% by volume, more preferably 75 to 90% by volume, and still more preferably 75 to 85% by volume.

As the high dielectric constant solvent, in addition to ethyl carbonate and propylene carbonate, for example, butyl carbonate, γ-butyrolactone, γ-valerolactone, tetrahydrofuran, 1,4-two are mentioned. Alkane, N-methyl-2-pyrrolidone, N-methyl-2-oxazolidinone, cyclobutyl hydrazine, 2-methylcyclobutyl hydrazine, and the like.

As the aforementioned low viscosity solvent, diethyl carbonate and/or ethyl methyl carbonate are used in the present invention. Among them, diethyl carbonate is particularly desirable. As a low viscosity solvent, although dimethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl butyrate, dibutyl carbonate, dimethoxy B are known. Alkane, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, methyl propionate, ethyl propionate, methyl formate, ethyl formate, methyl butyrate , various solvents such as methyl isobutyrate, but in the present invention, an organic solvent containing 70% by volume or more of diethyl carbonate and/or ethyl methyl carbonate is used as a low viscosity solvent, and by the above formula (1) The combination of the compounds shown can improve the durability of the battery, and the electric vehicle equipped with the battery using the organic electrolyte of the present invention can suppress deterioration caused by repeated charge and discharge over a long period of time.

Examples of the electrolyte salt include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium hexafluoroantimonate (LiSbF ₆ ), and lithium perchlorate (LiClO _{4 ).} And an inorganic lithium salt such as lithium tetrachloroaluminate (LiAlCl ₄ ), and lithium trifluoromethanesulfonate (CF ₃ SO ₃ Li), lithium bis(trifluoromethyl sulfonium) ruthenium [(CF ₃ SO ₂ ) ₂ NLi], bis(pentafluoroacetamidine) quinone imide lithium [(C ₂ F ₅ SO ₂ ) ₂ NLi] and ginseng (trifluoromethyl hydrazine) methylated lithium [(CF ₃ SO ₂ ) ₃ CLi], etc. A lithium salt of a perfluoroalkanesulfonic acid derivative. The electrolyte salt may be used singly or in combination of a plurality of types. The electrolyte salt is usually desirably contained in the organic electrolyte at a concentration of 0.5 to 3 m/liter, preferably 0.8 to 2 m/liter, more preferably 1.0 to 1.6 m/liter.

In addition to the compound according to the present invention, an electrode protective material such as a vinyl carbonate, a fluorocarbonic acid ethyl ester, a vinyl carbonate ethyl ester, a 1,3-propane sultone or a sulfite ethyl ester may be contained. For the electrolyte.

Moreover, the present invention provides an organic-based electrolyte secondary battery using the organic electrolyte of the present invention.

In the organic-based electrolyte storage battery of the present invention, it can be used as a positive electrode active material, and is a material capable of occluding and releasing lithium. For example, a lithium-containing composite oxide LiMO ₂ (M may be used alone or in combination of two or more metals selected from the group consisting of Mn, Fe, Co, Ni, etc., may also be partially Mg, Al, An olivine-type material typified by other cations such as Ti, LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ or the like, or LiFePO ₄ or LiMnPO ₄ . Further, a lithium-rich material such as Li ₂ MnO ₃ or Li ₂ MSiO ₄ (M is a metal) can be used. Preferably, the positive electrode contains lithium and a transition metal, and particularly preferably contains a layered oxide containing cobalt.

Artificial graphite or a carbon-based negative electrode material containing natural graphite is used for the negative electrode. As the negative electrode active material, a negative electrode active material capable of inserting or reacting with lithium is used. As the negative electrode active material, graphite is mainly used, but a carbon material such as amorphous carbon or a material such as Li metal, Si, Sn, or Al which forms an alloy with Li, Si oxide, and Si may be mixed. Si composite oxide with other metal elements other than Si, Sn oxide, Sn composite oxide containing a metal element other than Sn and Sn, Li ₄ Ti ₅ O ₁₂ or the like.

The separator may be composed of a porous body that is electrically insulating, and examples thereof include a polyolefin such as polyethylene or polypropylene, a polymer such as polyester, polyethylene terephthalate or polyimine. The film or fiber is not woven. The material can be used alone or in most cases. Further, the separator may be a single layer or a multilayer (composite film). Further, inorganic material nano particles such as ceramics may be contained. Further, a polymer compound such as polyvinylidene fluoride may be applied to both surfaces of the separator.

In the organic-based electrolyte storage battery of the present invention, an electrolyte which is gel-like by the inclusion of the polymer compound may be used, and the polymer compound is swollen by the organic solvent to form a support for holding the organic electrolyte. This is because high ion conductivity can be obtained by including a polymer compound which is swollen by an organic solvent, whereby excellent charge and discharge efficiency can be obtained, and leakage of the battery can be prevented. When the polymer compound is contained in the organic electrolyte, the content of the polymer compound is preferably in the range of 0.1% by mass or more and 10% by mass or less.

In the case where a polymer compound such as polyvinylidene fluoride is applied to both surfaces of the separator, the mass ratio of the organic electrolyte to the polymer compound is preferably in the range of 50:1 to 10:1. By setting it within this range, higher charge and discharge efficiency can be obtained.

Examples of the polymer compound include an ether polymer compound such as polyvinyl formaldehyde, polyethylene oxide, and a polyethylene oxide-containing crosslinked product, and an ester polymer such as polymethacrylate. A polymer of a vinylidene fluoride compound such as a compound, an acrylate-based polymer compound, and a copolymer of polyvinylidene fluoride and a copolymer of vinylidene fluoride and hexafluoropropylene. The polymer compound may be used singly or in combination of a plurality of types. In particular, from the viewpoint of the swelling preventing effect at the time of high-temperature storage, it is desirable to use a fluorine-based polymer compound such as polyvinylidene fluoride.

Generally, the higher the voltage (charging voltage) at the time of charging the battery, the more power the battery can be charged, and the output at the time of discharge can be increased. On the other hand, when the charging voltage is high, deterioration of the electrode material or the like is likely to occur, and there is a problem of reduction in repeatability or safety or economy. Therefore, the charging voltage of the organic electrolyte storage battery is currently generally 4.10 to 4.20V. However, since the organic-based electrolyte storage battery of the present invention has high durability, a higher charging voltage can be employed. Specifically, it can be used at a charging voltage higher than 4.20 V, preferably 4.25 V or higher, more preferably 4.35 V or higher, still more preferably 4.45 V or higher. [Examples]

Although the invention is specifically illustrated by the following examples, the invention is not limited to the embodiments. In addition, although the coin type organic electrolyte battery is described with reference to FIG. 1, the form of the organic electrolyte battery of the present invention is not limited to the coin type, and may be, for example, a button type, a bag type, a square type, or the like. Or an organic electrolyte storage battery having a cylindrical structure such as a spiral structure. Further, the size of the organic electrolyte storage battery is also arbitrary, and it can be large, small, or thin.

Fig. 1 is a schematic cross-sectional view showing the structure of a coin type organic-based electrolyte storage battery. This battery is a laminate in which the positive electrode 12 and the negative electrode 14 are laminated with the separator 15 interposed therebetween. The positive electrode 12, the negative electrode 14, and the separator 15 are all in the shape of a disk, and are accommodated in a space defined by the metal exterior part 11 and the exterior part 13. The inside of the exterior parts 11 and 13 is filled with an organic electrolyte, and the peripheral portions of the exterior parts 11 and 13 are sealed by interposing a gap by a gasket 17. Further, a metal spring 18 and a spacer 19 are disposed between the exterior member 13 and the negative electrode 14.

The positive electrode was produced in the following manner. In the active material: LiNi _1/3 Mn _1/3 Co _1/3 O ₂ 90% by weight, conductive auxiliary: acetylene black 5% by weight, binder: polyvinylidene fluoride 5 wt% mixture, add N- Methylpyrrolidone (hereinafter abbreviated as NMP) was kneaded to prepare a slurry. The produced slurry was dropped onto an aluminum current collector, formed into a film using a film applicator having a micrometer, and an automatic coater, and dried in an oven at 100 ° C under a nitrogen atmosphere. The prepared positive electrode was punched into a circular shape having a diameter of 15 mm, and then pressed. The mass of the positive electrode active material was about 16 mg.

The negative electrode was produced in the following manner. In the mixture of the active material: 94% by weight of artificial graphite, 1% by weight of a conductive auxiliary agent: acetylene black, and 5% by weight of a binder: polyvinylidene fluoride, NMP was added and kneaded to prepare a slurry. The produced slurry was dropped onto a copper current collector, formed into a film using a film applicator having a micrometer, and an automatic coater, and dried in an oven at 110 ° C under a nitrogen atmosphere. The prepared negative electrode was punched into a circular shape having a diameter of 15 mm, and then pressed. The mass of the negative electrode active material was about 10 mg.

A coin-type secondary battery was produced using a positive electrode made of the above method, a negative electrode, a separator made of polypropylene having a circular thickness of 25 μm, and various prepared organic electrolytes. As the organic solvent, a high dielectric constant solvent and a low viscosity solvent are used, and LiPF ₆ is dissolved at a ratio of 1 mol/liter in a solvent in which these are mixed in a predetermined volume ratio. Further, the purity of the compound was 97% or more. The high dielectric constant solvent uses ethyl carbonate (hereinafter referred to as EC); the low viscosity solvent uses diethyl carbonate (hereinafter abbreviated as DEC), or ethyl methyl carbonate (hereinafter referred to as EMC), or dimethyl carbonate (hereinafter referred to as EMC) Hereinafter referred to as DMC).

(Example 1) An organic electrolyte was prepared as shown in Table 1 below, and a coin battery was produced as described above.

【Table 1】

(Comparative Example 1) A coin-type secondary battery was produced in the same manner as in Example 1 except that an organic electrolyte having no compound and a compound was changed in the manner shown in Table 2 below.

【Table 2】

(Comparative Example 2) A coin-type secondary battery was produced in the same manner as in Example 1 except that an organic electrolyte having a low viscosity solvent changed to DMC was prepared as shown in Table 3 below.

【table 3】

(Example 2) A coin-type secondary battery was produced in the same manner as in Example 1 except that an organic electrolyte having a high dielectric constant solvent and a low viscosity solvent ratio was prepared as shown in Table 4 below.

【Table 4】

(Comparative Example 3) A coin-type secondary battery was produced in the same manner as in Example 1 except that an organic electrolyte having a high dielectric constant solvent and a low viscosity solvent ratio was prepared as shown in Table 5 below.

【table 5】

The coin type battery and the pouch type battery fabricated by the above method were placed in a thermostat at room temperature to perform a charge and discharge test. First, charging was performed for 8 hours at a constant current of 0.840 mA and a constant voltage of 4.45 V, and then discharging was performed at a constant current of 0.840 mA until 3.00 V. The discharge capacity at this time was taken as the initial storage capacity. After the initial charge and discharge, the battery was charged at a constant current of 1.68 mA and a constant voltage of 4.45 V for 4 hours, and was allowed to stand in a thermostat at 60 ° C in a charged state, and stored at a high temperature for 3 weeks. After the storage, the battery was discharged to 3.00 V at a current of 1.68 mA, charged at a constant current of 1.68 mA, and charged at a constant voltage of 4.45 V for 4 hours, and then discharged to 3.00 V at a current of 1.68 mA. The discharge capacity at this time is taken as the storage capacity after storage. The initial storage capacity of each battery and the storage capacity after storage are summarized in Table 6. In addition, since the batteries of Comparative 1-4 were deteriorated at the time of initial charge and discharge, the storage test was not performed.

[Table 6]

(Reference Example 1) An organic electrolyte was prepared as shown in Table 7 below, and a coin battery was produced in the same manner as in Example 1. The initial storage capacity of each battery and the storage capacity after storage were measured by changing the charging voltage to 4.20 V (reference 1-1 to 1-9) or 4.35 V (refer to 1-10 to 1-18). The measurement results are summarized in Table 8.

[Table 7] [Table 8]

As a result of the above, it is understood that any one of the formulas (1) to (4) is represented by using a high dielectric constant solvent and an organic solvent using diethyl carbonate and/or ethyl methyl carbonate as a low viscosity solvent. The organic electrolyte of the present invention having the compound has an effect of increasing the storage capacity after storage at a high temperature, that is, an effect of improving durability. Moreover, due to this durability, it can be used at a higher charging voltage than conventional ones. [Industrial use]

The organic-based electrolyte of the present invention has an effect of increasing the storage capacity after storage of the battery at a high temperature. When the battery using the organic-based electrolyte of the present invention is mounted on the electric vehicle, the durability of the battery can be improved, and the long-term reliability of the automobile can be improved. .

11‧‧‧ Exterior parts
12‧‧‧ positive
13‧‧‧ Exterior parts
14‧‧‧negative
15‧‧‧Parts
17‧‧‧shims
18‧‧‧ Spring
19‧‧‧ spacers

Fig. 1 is a schematic cross-sectional view showing the structure of a coin type organic-based electrolyte storage battery.

11‧‧‧ Exterior parts

12‧‧‧ positive

13‧‧‧ Exterior parts

14‧‧‧negative

15‧‧‧Parts

17‧‧‧shims

18‧‧‧ Spring

19‧‧‧ spacers

Claims (6)

An organic electrolyte comprising an organic solvent composed of a high dielectric constant solvent and a low viscosity solvent, and a compound represented by any one of the following formulas (1) to (4), wherein the low viscosity solvent is carbonic acid Diethyl ester and/or ethyl methyl carbonate, the ratio of the low viscosity solvent in the organic solvent is 70% by volume or more; (In the formula (1), R ₁ to R ₁₁ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or Halogen, R ₁₂ to R ₁₃ are a hydrogen atom, "methyl, ethyl or halogen-containing methyl, ethyl" or halogen, and R ₁₄ is an unsubstituted or substituted cyclohexyl group having a maximum number of substituents of 11, Each of which is independently a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or a halogen; (In the formula (2), R ₁ to R ₁₁ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, Or halogen, R ₁₂ is a linear alkyl group having a carbon number of 3 or 4, a part of hydrogen may be substituted with a halogen and/or a "methyl or halogen-containing methyl group", and R ₁₃ is unsubstituted or substituted. a cyclohexyl group having a maximum number of substituents of 11, and each independently being a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or a halogen); 3] (In the formula (3), R ₁ to R ₁₄ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or Halogen); [Chemical 4] (In the formula (4), R ₁ to R ₁₆ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen-containing linear or branched alkyl group having 1 to 4 carbon atoms, or halogen). The organic electrolyte according to the first aspect of the invention, wherein the compound represented by any one of the formulae (1) to (4) is blended in an amount of 0.05 to 10% by weight based on the organic electrolyte. The organic electrolyte according to claim 1 or 2, wherein the compound represented by any one of the formulae (1) to (4) is selected from the group consisting of 1,1-dicyclohexylethane and 1-cyclohexyl-1. -(2,5-Dimethylcyclohexyl)ethane, 1-cyclohexyl-1-(2,3-dimethylcyclohexyl)ethane, 1-cyclohexyl-1-(2,4-dimethyl Ethylcyclohexyl)ethane, 1-cyclohexyl-1-(4-ethylcyclohexyl)ethane, 1,3-dicyclohexylpropane, 1,4-dicyclohexylbutane, 1,3-bicyclo At least one of hexylbutane, trans octahydroquinone and cis octahydroindole. An organic-based electrolyte storage battery characterized by using the organic-based electrolyte according to any one of claims 1 to 3. An organic electrolyte storage battery according to claim 4, wherein the charging voltage is higher than 4.20V. An organic electrolyte storage battery according to the fourth or fifth aspect of the invention, wherein the positive electrode comprises cobalt, nickel or manganese.