JP2006269374A - Nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a battery output characteristic by improving an impregnation property of a molten salt electrolyte into an electrolyte and a separator, in a nonaqueous electrolyte battery using an ambient temperature molten salt. <P>SOLUTION: In a nonaqueous electrolyte battery provided with: a negative electrode containing or storing and releasing lithium; a positive electrode arranged separately from the negative electrode and storing and releasing lithium; and the molten salt electrolyte contacting the positive electrode and the negative electrode, containing a lithium salt and being in a molten state at ordinary temperature, this nonaqueous electrolyte battery contains 0.2-5% of perfluoropolyether in the molten salt electrolyte. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a nonaqueous electrolyte battery using a room temperature molten salt.

  In recent years, the market for portable information devices such as mobile phones, small personal computers, and portable audio devices is rapidly expanding. Non-aqueous electrolyte secondary batteries with high energy density are frequently used in these portable devices, and research for improving the performance is still ongoing. Mobile devices are assumed to be carried by humans, and therefore must perform in various environments and ensure their safety.

This type of non-aqueous electrolyte secondary battery uses a lithium-containing cobalt composite oxide and a lithium-containing nickel composite oxide as a positive electrode material, a carbon-based material such as graphite or coke as a negative electrode active material, and an electrolyte. Lithium salts such as LiPF ₆ and LiBF ₄ are used by dissolving them in an organic solvent such as ethylene carbonate and diethyl carbonate. The positive electrode and the negative electrode are molded into a sheet shape, hold the electrolytic solution, and face each other through a separator that electrically insulates the positive and negative electrodes, and are housed in various shaped containers to form a battery.

  Non-aqueous electrolyte secondary batteries such as those described above cause thermal instability due to a chemical reaction that differs from the original charge / discharge when used unexpectedly during overcharge, etc., and the electrolyte is flammable. Since the organic solvent is a main component, the safety of the battery may be impaired by the combustion. Further, when the outside air temperature rises, the internal pressure rises due to the vaporization of the internal electrolyte, and when the temperature is too high, there is a possibility of the explosion of the exterior material and the accompanying ignition. Furthermore, if the internal electrolyte leaks due to external impact, deformation, or scratches, they are flammable liquids, and there is a possibility of ignition and combustion.

  In order to solve such a problem, it has been studied to dramatically improve safety by using a room temperature molten salt having no flash point as an electrolyte. A room temperature molten salt is a liquid consisting only of ions that show a molten state at room temperature, and is also called an ionic liquid. In recent years, room temperature molten salts using a nitrogen-containing compound that is stable in the atmosphere as a cation have been developed, and research for applying these to batteries has become active. As the nitrogen-containing compound cation, quaternary ammonium, imidazolium, pyridinium, and the like have been studied. For example, lithium metal oxide is used for the positive electrode, lithium metal, lithium alloy, or a carbonaceous material that absorbs and releases lithium ions is used for the negative electrode, and the lithium electrolyte, aluminum halide, and quaternary ammonium halide are used as the electrolyte. A non-aqueous electrolyte secondary battery using a room temperature molten salt is disclosed, for example, in Japanese Patent Application Laid-Open No. 4-349365 (Patent Document 1) as a secondary battery excellent in safety. Also used is a molten salt composed of a positive electrode, a negative electrode containing a carbonaceous material that occludes / releases lithium ions, a lithium ion, and a quaternary ammonium ion and a fluoride anion of an element selected from boron, phosphorus, and sulfur. For example, Japanese Patent Application Laid-Open No. 11-86905 (Patent Document 2) discloses a non-aqueous electrolyte secondary battery that has excellent safety and has improved cycle life and discharge capacity. However, these molten salts have a problem in that impregnation into positive and negative electrodes and separators is difficult in addition to extremely low output characteristics due to low ionic conductivity.

  In order to solve these problems, it has been studied to add a conventionally used non-aqueous solvent such as diethyl carbonate and ethylene carbonate to the molten salt. However, even if the molten salt is nonflammable or flame retardant, there is a problem that the safety, which is a great advantage obtained by using the molten salt, is impaired by adding a flammable organic solvent. .

Even in a molten salt containing a hexafluoroborate anion (abbreviation: BF ₄ ⁻ ) or a bistrifluoromethanesulfonylamide anion (abbreviation: TFSI), which has a relatively low viscosity in various molten salts, the conventional carbonate type, etc. Compared with organic electrolytes of this type, the viscosity is high, and impregnation into the porous positive and negative electrodes and separators constituting the battery is very difficult, which results in the problem of reduced capacity and reduced output characteristics.

In addition, even for primary batteries that use lithium metal or lithium alloys containing lithium as the negative electrode, safety can be improved by using molten salt as the electrolyte. There was a problem that the reduction was likely to occur.
JP-A-4-349365 JP 11-86905 A

  An object of the present invention is to improve the impregnation property of a room temperature molten salt electrolyte, which is difficult to impregnate due to high viscosity in a non-aqueous electrolyte battery using a room temperature molten salt electrolyte.

  In order to solve the above problem, a non-aqueous electrolyte battery according to claim 1 includes a negative electrode containing or absorbing / desorbing lithium, a positive electrode arranged separately from the negative electrode and inserting and extracting lithium, and contacts the positive electrode and the negative electrode. And a non-aqueous electrolyte battery comprising a molten salt electrolyte containing lithium salt and in a molten state at room temperature, the perfluoropolyether represented by the formula (1) in the molten salt electrolyte is 0.2% or more and 5% or more. % Non-aqueous electrolyte battery characterized by containing.

R ₁ -[(OC R ₂ R ₃ -CF ₂ ) _n- (O-CF ₂ ) _m ] -OR ₄ (1)
In the formula, n / m is 0.5 or more and 1000 or less, R ₁ and R ₄ are perfluoroalkyl groups having 1 to 3 carbon atoms, and R ₂ and R ₃ are fluorine or perfluoroalkyl having 1 to 3 carbon atoms. Represents a group. Further, it may be a block copolymer or a random copolymer.

  The nonaqueous electrolyte battery according to claim 2 is characterized in that, in claim 1, the negative electrode is a lithium-containing titanium oxide.

  The nonaqueous electrolyte battery according to claim 3 is characterized in that, in claim 1, the molten salt electrolyte includes a lithium salt and a molten salt composed of an anion containing fluorine and a cation having an imidazolium skeleton.

  A nonaqueous electrolyte battery according to a fourth aspect is the nonaqueous electrolyte battery according to the second aspect, wherein the positive electrode includes a lithium composite oxide containing a metal selected from at least one of cobalt, manganese, and nickel.

The positive electrode contains a lithium composite oxide containing at least one of cobalt, manganese, and nickel as a positive electrode active material, and can occlude and release lithium ions. Various oxides, for example, chalcogen compounds such as lithium-containing cobalt composite oxide, lithium-containing nickel cobalt composite oxide, lithium-containing nickel composite oxide, and lithium manganese composite oxide can be used as the positive electrode active material. Among these, lithium-containing cobalt composite oxide, lithium-containing nickel-cobalt composite oxide, lithium-containing manganese composite oxide, and the like having a charge / discharge potential of 3.8 V or more with respect to the lithium metal potential are preferable because high battery capacity can be realized. Further, since it suppress the decomposition reaction of the molten salt in the cathode surface at room temperature or _{higher, LiCo x Ni y Mn z O} 2 (x + y + z = 1,0 <x ≦ 0.5,0 ≦ y <1,0 ≦ z < The positive electrode active material represented by 1) is particularly desirable.

  The negative electrode contains a negative electrode active material that can occlude and release lithium ions like the positive electrode and can occlude and release lithium ions at a lower potential than the combined positive electrode. Those having such characteristics include lithium metal or carbonaceous materials such as artificial and natural graphite, non-graphitizable carbon, graphitizable low-temperature calcined carbon, lithium titanate, iron sulfide, cobalt oxide, lithium aluminum alloy, tin oxide, etc. Is mentioned. Furthermore, an active material in which the operating potential of the negative electrode is nobler than 0.5 V with respect to the potential of metallic lithium is desirable. By selecting such an active material, it is possible to suppress deterioration due to side reaction of the molten salt on the negative electrode active material surface. As the negative electrode active material, lithium-containing titanium oxides that are excellent in lithium occlusion / release repetitive characteristics are most desirable. Furthermore, a mixture of two or more negative electrode active materials can be used. Various shapes such as flakes, fibers, and spheres are possible.

  The positive electrode and the negative electrode preferably contain a carbonaceous material as a conductive aid.

The molten salt electrolyte is composed of a molten salt and a lithium salt.

  The cation forming the molten salt is not particularly limited, but 1-ethyl-3-methylimidazolium, 1-methyl-3-propylimidazolium, 1-methyl-3-isopropylimidazolium, 1-ethyl-3-methylimidazolium, Butyl-3-methylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-ethyl-3,4-dimethylimidazolium, N-propylpyridinium, N-butylpyridinium, N-tert-butylpyridinium, N Aromatic quaternary ammonium ions such as tert-pentylpyridinium, N-butyl-N, N, N-trimethylammonium, N-ethyl-N, N-dimethyl-N-propylammonium, N-butyl-N-ethyl -N, N-dimethylammonium, N-butyl-N, N-dimethyl-N-propyla Monium, N-methyl-N-propylpyrrolidinium ion, N-butyl-N-methylpyrrolidinium ion, N-methyl-N-pentylpyrrolidinium, N-propoxyethyl-N-methylpyrrolidinium, N-methyl -N-propylpiperidinium, N-methyl-N-isopropylpiperidinium, N-butyl-N-methylpiperidinium, N-isobutyl-N-methylpiperidinium, N-sec-butyl-N-methyl One or more kinds of aliphatic quaternary ammonium ions such as piperidinium, N-methoxyethyl-N-methylpiperidinium, and N-ethoxyethyl-N-methylpiperidinium can be used. In particular, when a cation having an imidazolium skeleton is used, a molten salt having a low viscosity can be obtained, and high battery output characteristics can be obtained when used as an electrolyte. Furthermore, when an active material having an operating potential nobler than 0.5 V with respect to the metal lithium potential is used as the negative electrode active material, side reactions on the negative electrode are suppressed even in a molten salt containing a cation having the imidazolium skeleton, A nonaqueous electrolyte secondary battery excellent in storage and cycle characteristics can be obtained.

Examples of the lithium salt include lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoromethanesulfonate, lithium bistrifluoromethanesulfonylamide (LiTFSI), lithium dicyanamide (LiDCI), and the like. 1 or more types can be used. In order to improve the characteristics in a relatively high temperature environment such as 60 ° C., it is desirable that the alkali metal salt has the same anion species as the anion of the molten salt.

  The electrolyte is composed of one or more types of the molten salt and one or more types of the lithium salt. In order to obtain as high a flame retardance as possible, it is desirable not to include an organic solvent other than the above. However, other organic solvents may be included for the purpose of suppressing side reactions in the battery. However, in order to maintain flame retardancy, the addition amount is desirably 5% by weight or less. In addition, when adding another organic solvent for controlling the chemical reaction in the battery such as side reaction suppression, it is more desirable that the amount added is more than half of the added amount after the battery configuration or after the completion of the initial charge / discharge. The amount added is 3% by weight or less based on the total amount of the electrolyte.

  Carbon dioxide may be contained in the electrolyte. Since carbon dioxide is a non-flammable gas, side reactions on the negative electrode surface can be suppressed without impairing flame retardancy, and an increase in internal impedance and an improvement in cycle characteristics can be obtained.

  As the separator, a porous sheet or nonwoven fabric made of polyolefin or polyester can be used. In particular, it is desirable to use a polypropylene nonwoven fabric, which is a kind of polyolefin, or a polyethylene terephthalate nonwoven cloth, which is a kind of polyester, because high output characteristics can be obtained and better cycle characteristics can be obtained. This is presumed to be due to the affinity with liquid salt and liquid retention.

  The perfluoropolyether is represented by the formula (1). Since the perfluoropolyether has a high molecular weight, it has a high boiling point, and can greatly reduce volatilization due to the battery manufacturing process or when the battery container is damaged. Furthermore, since it is nonflammable, the flame retardance of molten salt is not impaired. Since the perfluoropolyether has a low viscosity, the average molecular weight is preferably 500 to 4000. More desirably, the average molecular weight is 900 or more. By setting the molecular weight within this range, the boiling point becomes 200 ° C. or more, and the volatility is further suppressed. If n / m is between 0.5 and 1000, similar performance can be obtained because of similar characteristics.

  ADVANTAGE OF THE INVENTION According to this invention, the impregnation property of molten salt electrolyte can be improved and the nonaqueous electrolyte battery excellent in the output characteristic can be provided.

  Hereinafter, an embodiment of the nonaqueous electrolyte battery of the present invention will be described in detail with reference to FIG. However, FIG. 1 is a cross-sectional view of the nonaqueous electrolyte secondary battery cut in a direction perpendicular to the central axis around which the electrode is wound.

  This non-aqueous electrolyte secondary battery has a positive electrode 1, a separator 3, and a negative electrode 2 stacked in a coin-type battery container 4. The non-aqueous electrolyte is accommodated in the battery container 4 and has an electrically insulating gasket ( The upper and lower parts of the battery container 4 are connected and sealed via a not-shown). The voids in the separator 3, the positive electrode 1, and the negative electrode 2 are impregnated with a nonaqueous electrolyte.

  The positive electrode 1 contains a positive electrode active material, and can further contain a material having electronic conductivity such as carbon, or a binder for forming a sheet-like or pellet-like shape, and a metal having electronic conductivity. A base material such as a current collector can be used in contact with the current collector.

  As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), ethylene-propylene-diene copolymer, styrene-butadiene rubber, or the like can be used.

As the current collector, a metal foil such as aluminum, stainless steel, or titanium, a thin plate or mesh, a wire mesh, or the like can be used.

  The positive electrode active material and the conductive material can be pelletized or formed into a sheet by adding the binder and kneading and rolling. Alternatively, after dissolving and suspending in a solvent such as toluene and N-methylpyrrolidone (NMP) to form a slurry, it can be applied onto the current collector and dried to form a sheet.

  The negative electrode 2 contains a negative electrode active material, and is formed into a pellet shape, a thin plate shape, or a sheet shape using a conductive agent, a binder, or the like.

As the conductive material, a material having electronic conductivity such as carbon or metal can be used. Shapes such as powder and fibrous powder are desirable.

As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), styrene-butadiene rubber, carboxymethyl cellulose (CMC), or the like can be used. As the current collector, a metal foil such as copper, stainless steel, nickel or the like, a thin plate or mesh, a wire net, or the like can be used.

  The negative electrode active material and the conductive material can be pelletized or sheeted by adding the binder and kneading and rolling. Alternatively, after dissolving and suspending in water, a solvent such as N-methylpyrrolidone (NMP) to form a slurry, it can be applied onto the current collector and dried to form a sheet.

  As the separator 3, for example, a synthetic resin nonwoven fabric, a polyethylene porous film, a polypropylene porous film, a cellulose porous sheet, or the like can be used.

  As the battery container 4, a coin type made of stainless steel or iron is used. The upper part and the lower part are sealed by being crimped with a gasket interposed therebetween. It is also possible to use containers of various shapes such as a cylindrical shape and a square shape, and laminated film bags.

  For the gasket, polypropylene, polyethylene, vinyl chloride, polycarbonate, Teflon (R), or the like can be used.

  FIG. 1 shows an example using a coin-type container. The lower surface is a positive terminal and the upper surface is a negative terminal.

  Hereinafter, examples of the present invention will be described in detail with reference to the drawings. The following examples employ the battery structure shown in FIG. 1, but are not limited to this structure.

Example 1
90% by weight of lithium cobalt oxide (Li ₂ CoO ₂ ) powder as a positive electrode active material, 2.5% by weight of acetylene black, 2.5% by weight of graphite, 3.5% by weight of polyvinylidene fluoride as a binder, N-methylpyrrolidone Slurry as a solvent, coated on a 20 μm thick aluminum foil (metal foil serving as a positive electrode current collector) at a coating amount of 66 g / m ² (total amount of solid content after drying per unit area), and after drying, the packing density was 0 Rolled to .0030 g / mm ³ . The obtained positive electrode sheet was cut into a width of 50.5 mm and a length of 210 mm to prepare the positive electrode 1. The coated layer was peeled off in a strip shape for 5 mm of the positive electrode end portion to create an aluminum exposed portion, and an aluminum ribbon having a width of 3 mm and a length of 50 mm was attached to the exposed portion by ultrasonic welding to form a positive electrode tab 5. As a result of peeling off the coating layer, the size of the coated part was 50.5 mm wide and 205 mm long.

As a negative electrode active material, 90% by weight of Li _4/3 Ti _5/3 O ₄ powder, 5% by weight of artificial graphite, and 5% by weight of polyvinylidene fluoride (PVdF) were added to an N-methylpyrrolidone (NMP) solution and mixed. The obtained slurry was applied to an aluminum foil having a thickness of 20 μm (a metal foil serving as a negative electrode current collector) at an application amount of 70 g / m ² (total amount of solid content after drying per unit area), and after drying, the packing density was 0. Rolled to 0019 g / mm ³ . The obtained negative electrode sheet was cut into a width of 50.0 mm and a length of 205 mm to prepare a negative electrode 2. The coated layer was peeled off in the form of a strip for 5 mm of the negative electrode end portion to create an aluminum exposed portion, and an aluminum ribbon having a width of 3 mm and a length of 50 mm was attached to the exposed portion by ultrasonic welding to form a negative electrode tab 6. As a result of peeling off the coating layer, the size of the coated part was 50.0 mm wide and 200 mm long.

  The separator 3 was a polypropylene non-woven fabric, cut into a width of 56 mm and a length of 280 mm.

The positive electrode 1 and the negative electrode 2 were laminated via the separator 3. At this time, all the application parts of the negative electrode 2 faced each other so as to face the application part of the positive electrode 1. Thereafter, folding was performed a plurality of times every 40 mm in the long direction, and an electrode group having a long side of 56 mm and a short side of 40 mm was obtained as a whole.

2.0 mol / L of lithium tetrafluoroborate (LiBF ₄ ) is dissolved in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI · BF ₄ ), and R1, R2, and R4 of formula (1) are further dissolved. An electrolyte was prepared by mixing 0.5% of a perfluoropolyether having a molecular weight of about 1500, wherein n is a trifluoromethyl group, R3 is fluorine and n / m = 30.

  The electrode group was wrapped with aluminum laminate 4, and three sides of the aluminum laminate were heat-sealed to form a bag. At this time, the aluminum ribbon of the positive electrode 1 and the aluminum ribbon of the negative electrode 2 were allowed to come out from the aluminum laminate bag through the heat-sealing seal portion. After the electrolyte was added to the aluminum laminated bag containing the electrode group, it was impregnated in a vacuum state, and the remaining side of the aluminum laminated bag was heat-sealed and sealed in a vacuum state to produce a nonaqueous electrolyte secondary battery.

(Example 2)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that 0.2% of the perfluoropolyether was mixed.

(Example 3)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that 1.0% of the perfluoropolyether was mixed.

Example 4
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that 5.0% of the perfluoropolyether was mixed.

(Example 5)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the perfluoropolyether having an average molecular weight of about 3200 was used.

(Example 6)
In the same manner as in Example 1, except that R1 and R4 are trifluoromethyl groups, R2 and R3 are fluorine, and n / m is 1 and an average molecular weight of about 4000 perfluoropolyether is used. A water electrolyte secondary battery was produced.

(Example 7)
Except that 1.0 mol / L bistrifluoromethanesulfonylamide lithium (LiTFSI) was dissolved in 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylamide (EMI • TFSI), the same as in Example 1 was performed. A water electrolyte secondary battery was produced.

(Example 8)
Except that 1.0 mol / L bistrifluoromethanesulfonylamidolithium (LiTFSI) was dissolved in 1-ethyl-3-methylimidazolium 1-ethyl-2-methyl-3-methylimidazolium (EMMI • TFSI), A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1.

Example 9
Example 1 was repeated except that 1.0 mol / L bispentafluoroethanesulfonylamidolithium (LiBETI) was dissolved in 1-ethyl-3-methylimidazolium bispentafluoroethanesulfonylamide (EMI • BETI). Thus, a non-aqueous electrolyte secondary battery was produced.

(Example 10)
Except that 0.8 mol / L bistrifluoromethanesulfonylamide lithium (LiTFSI) was dissolved in N-methyl-N-propylpiperidinium bistrifluoromethanesulfonylamide (13P6 · TFSI), the same procedure as in Example 1 was performed. A non-aqueous electrolyte secondary battery was produced.

(Example 11)
90% by weight of lithium nickel oxide (Li ₂ NiO ₂ ) powder as a positive electrode active material, 2.5% by weight of acetylene black, 2.5% by weight of graphite, 3.5% by weight of polyvinylidene fluoride as a binder, N-methylpyrrolidone Slurry as a solvent, coated on an aluminum foil having a thickness of 20 μm (metal foil serving as a positive electrode current collector) at a coating amount of 52 g / m ² (total amount of solid content after drying per unit area), and after drying, the packing density was 0 Rolled to .0028 g / mm ³ . A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the obtained positive electrode sheet was cut into a width of 50.5 mm and a length of 210 mm to produce the positive electrode 1.

(Comparative Example 1)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that no perfluoropolyether was added.

(Comparative Example 2)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 7 except that no perfluoropolyether was added.

(Comparative Example 3)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 9 except that no perfluoropolyether was added.

(Comparative Example 4)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 10 except that no perfluoropolyether was added.

(Comparative Example 5)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 11 except that no perfluoropolyether was added.

About the obtained non-aqueous electrolyte secondary batteries of Examples 1 to 11 and Comparative Examples 1 to 5, the battery was charged at a constant current of 2.8 V at 20 mA (0.2 C), and after reaching 2.8 V, 2.8 V was reached. The battery was charged at a constant voltage until the total time was 8 hours. Then, constant current discharge of 20 mA was performed to 1.5V. Thereafter, after charging under the same conditions as described above, discharging at 20 mA (0.2 C), 50 mA (0.5 C) and 100 mA (1 C) was performed up to 1.5 V, and the discharge capacity was measured. The obtained discharge capacity is shown in Table 1.

As is clear from Table 1, the nonaqueous electrolyte secondary batteries of Examples 1 to 11 obtained a higher discharge capacity from the initial discharge than Comparative Examples 1 to 5, and exhibited high output characteristics.

Sectional drawing of the nonaqueous electrolyte secondary battery which concerns on embodiment of invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Positive electrode 2 ... Negative electrode 3 ... Separator 4 ... Aluminum laminate 5 ... Positive electrode tab 6 ... Negative electrode tab

Claims (4)

A negative electrode containing or occluding and releasing lithium; a positive electrode which is disposed apart from the negative electrode and occluding and releasing lithium; and a molten salt electrolyte which is in contact with the positive electrode and the negative electrode and contains a lithium salt and which is in a molten state at room temperature. A nonaqueous electrolyte battery comprising: a perfluoropolyether represented by the formula (1) in the molten salt electrolyte in an amount of 0.2% to 5%.
R ₁ -[(OC R ₂ R ₃ -CF ₂ ) _n- (O-CF ₂ ) _m ] -OR ₄ (1)
In the formula, n / m is 0.5 or more and 1000 or less, R ₁ and R ₄ are perfluoroalkyl groups having 1 to 3 carbon atoms, and R ₂ and R ₃ are fluorine or perfluoroalkyl having 1 to 3 carbon atoms. Represents a group.   The nonaqueous electrolyte battery according to claim 1, wherein the negative electrode is a lithium-containing titanium oxide.   The non-aqueous electrolyte battery according to claim 1, wherein the molten salt electrolyte includes a lithium salt and a molten salt composed of an anion containing fluorine and a cation having an imidazolium skeleton. The non-aqueous electrolyte battery according to claim 2, wherein the positive electrode includes a lithium composite oxide containing a metal selected from at least one of cobalt, manganese, and nickel.

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