JP2002008715A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery having both excellent low-temperature characteristics and high energy density. SOLUTION: This nonaqueous electrolyte battery is formed of, at least, a positive electrode mainly composed of the positive electrode active material, a negative electrode mainly composed of the negative electrode active material, and the nonaqueous electrolyte included in the non-aqueous solvent. In this non-aqueous electrolyte battery, the non-aqueous electrolyte includes γ- butyrolactone, phenylene carbonate or the derivative thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte battery, and more particularly to a non-aqueous electrolyte battery having good low-temperature characteristics and high energy density.

[0002]

2. Description of the Related Art In recent years, non-aqueous electrolyte batteries, particularly lithium secondary batteries, have been used as power supplies for portable devices such as portable telephones, PHS (simple portable telephones), and small computers, and as power supplies for power storage,
It is attracting attention as a power source for electric vehicles.

A lithium secondary battery generally includes a positive electrode having a positive electrode active material as a main component, a negative electrode having a negative electrode active material as a main component, and a non-aqueous electrolyte.

As a positive electrode active material constituting a lithium secondary battery, a lithium-containing transition metal oxide is used. As a negative electrode active material, a carbonaceous material represented by graphite is used. As a nonaqueous electrolyte, hexafluoride is used. Lithium phosphate (LiP
It is widely known that an electrolyte such as F ₆ ) is dissolved in a non-aqueous solvent of ethylene carbonate.

However, ethylene carbonate has a low melting point, and the electrolyte is easily coagulated at a low temperature. Therefore, in place of ethylene carbonate, a method of using propylene carbonate having a higher melting point as a non-aqueous solvent for an electrolytic solution is known.However, propylene carbonate is decomposed on a graphite negative electrode during a charging operation, so that charging is sufficiently performed. There was a problem that it was not possible.

As means for solving this problem, Japanese Patent Laid-Open No.
Patent Document 1-67266 discloses a technique in which a non-aqueous solvent containing propylene carbonate and vinylene carbonate for suppressing the decomposition of propylene carbonate as essential components is applied to a non-aqueous electrolyte battery. It is said that a non-aqueous electrolyte battery having low-temperature characteristics and high battery characteristics can be obtained. However, even with the means disclosed in the above publication, the improvement in low-temperature characteristics is insufficient, and there is a need for a non-aqueous electrolyte battery that achieves both high-temperature characteristics and high battery characteristics at a high level.

On the other hand, Japanese Patent Laid-Open No. 4-75266 discloses that
A technique in which a derivative of phenylene carbonate is used as a solvent for an electrolytic solution is disclosed, and it is said that oxidation resistance is improved. However, the derivative of phenylene carbonate has a high melting point, and there is a problem that low-temperature characteristics cannot be improved when used alone.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a nonaqueous electrolyte battery having both good low-temperature characteristics and high energy density. .

[0009]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have made intensive studies and found that the non-aqueous solvent constituting the non-aqueous electrolyte is specified to be surprising. In particular, they have found that a non-aqueous electrolyte battery having both good low-temperature characteristics and high energy density can be obtained, and have reached the present invention. That is, the technical configuration of the present invention and the operation and effect thereof are as follows. However, the mechanism of action includes estimation, and its correctness does not limit the present invention.

That is, the nonaqueous electrolyte battery according to claim 1 includes a positive electrode having a positive electrode active material as a main component, a negative electrode having a negative electrode active material as a main component, and an electrolyte salt contained in the nonaqueous solvent. A nonaqueous electrolyte battery comprising at least a nonaqueous electrolyte, wherein the nonaqueous electrolyte contains γ-butyrolactone and phenylene carbonate or a derivative thereof as the nonaqueous solvent.

Here, phenylene carbonate refers to benzo [1,3] dioxyzol-2-one, and derivatives of phenylene carbonate include, for example, 4-methyl-benzo [1,3] dioxyzol-2-one, 5-methyl-benzo [1,
3] dioxyzol-2-one and the like. According to such a configuration, for example, γ-butyrolactone has a higher ionic conductivity and a lower viscosity than ethylene carbonate or propylene carbonate, so that even at a low temperature,
Ion conduction can be ensured without increasing the viscosity of the electrolytic solution. In addition, the presence of phenylene carbonate or a derivative thereof can reliably suppress the decomposition of γ-butyrolactone on the negative electrode during charging, so that charging can be performed sufficiently. Therefore, a nonaqueous electrolyte battery having good low-temperature characteristics and high energy density can be obtained.

A non-aqueous electrolyte battery according to a second aspect is characterized in that the negative electrode active material is graphite. Graphite is preferred as a negative electrode active material of a non-aqueous electrolyte battery because it has an operating potential very close to metallic lithium and can reduce the irreversible capacity in charge and discharge, and further, as a non-aqueous solvent, γ-butyrolactone and phenylene carbonate or the same. By using the non-aqueous electrolyte containing the derivative together, as described above, γ-butyrolactone is decomposed on the negative electrode containing graphite as a main component at the time of charging, and the characteristics of graphite are deteriorated. Can be reliably avoided. Therefore, by using graphite as the negative electrode active material and lithium salt as the electrolyte salt, a non-aqueous electrolyte battery with less self-discharge and less irreversible capacity in charge and discharge can be obtained.

A non-aqueous electrolyte battery according to a third aspect is characterized in that the electrolyte salt is lithium tetrafluoroborate (LiBF ₄ ). LiBF ₄ is compared with other fluorine-based lithium salts widely used as electrolyte salts,
Since it has low reactivity with water present in the electrolytic solution, the degree of hydrofluoric acid generation that causes corrosion of electrodes and exterior materials is small.
Therefore, even when a thin material such as a metal-resin composite film is used as an exterior material for the purpose of weight reduction, a non-aqueous electrolyte battery having high durability can be obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

A nonaqueous electrolyte battery according to the present invention comprises a positive electrode having a positive electrode active material as a main component, a negative electrode having a negative electrode active material as a main component, and a nonaqueous electrolyte containing an electrolyte salt in a nonaqueous solvent. A nonaqueous electrolyte battery separator is generally provided between the positive electrode and the negative electrode.

The non-aqueous electrolyte contains γ-butyrolactone and phenylene carbonate or a derivative thereof as non-aqueous solvents. According to such a configuration, γ-butyrolactone has high ionic conductivity and Since the viscosity is low, the ionic conduction can be ensured without increasing the viscosity of the electrolytic solution even at a low temperature. In addition, the presence of phenylene carbonate or a derivative thereof can reliably suppress the decomposition of γ-butyrolactone on the negative electrode during charging, and can sufficiently perform charging, so that a non-aqueous electrolyte battery having a high energy density can be obtained. Obtainable.

The amount of phenylene carbonate or a derivative thereof is from 0.01% by weight to 1% based on the total weight of γ-butyrolactone and phenylene carbonate or a derivative thereof.
0% by weight, more preferably 0.1% by weight.
0 to 5% by weight. The amount of phenylene carbonate or a derivative thereof is set to be 0,0 based on the total weight of phenylene carbonate or a derivative thereof and γ-butyrolactone.
When the content is 01% by weight or more, the decomposition of γ-butyrolactone during the charging operation can be almost completely suppressed, and the charging can be performed more reliably. When the content is 10% by weight or less, the viscosity of the electrolytic solution does not become too high, so that ionic conduction can be ensured even at a low temperature.

In the mixed solvent composed of γ-butyrolactone and phenylene carbonate or a derivative thereof, since both γ-butyrolactone and phenylene carbonate or a derivative thereof are high-boiling solvents, volatilization of the electrolytic solution through the exterior material can be suppressed. Although it is preferable as a non-aqueous solvent for the electrolytic solution also in this point, another organic solvent such as a low-viscosity solvent may be added as needed as long as the above object can be achieved. That is, examples of such other organic solvents include cyclic carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate, and vinylene carbonate;
Cyclic esters such as valerolactone; chain carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate; chain esters such as methyl acetate and methyl butyrate; tetrahydrofuran or derivatives thereof;
Ethers such as 1,3-dioxane, 1,2-dimethoxyethane, and methyldiglyme; nitriles such as acetonitrile and benzonitrile; dioxalane or a derivative thereof; sulfolane, sultone or a derivative thereof, alone or in combination of two or more thereof Although a mixture etc. can be mentioned, it is not limited to these.

As the electrolyte salt, for example, LiCl
O_Four, LiBF_Four, LiAsF₆, LiPF₆, LiCF_Three
SO_Three, LiN (CF_ThreeSO_Two)_Two, LiN (C_TwoF_FiveS
O_Two)_Two, LiSCN, LiBr, LiI, Li_TwoSO_Four,
Li_TwoB_TenCl_Ten, NaClO_Four, NaI, NaSCN,
NaBr, KCLO_Four, KSCN and other lithium (L
i) one of sodium (Na) or potassium (K)
Inorganic ion salt containing LiN (CF _ThreeSO_Two)_Two, LiN
(C_TwoF_FiveSO_Two)_Two, (CH_Three)_FourNBF_Four, (CH_Three)_FourN
Br, (C_TwoH_Five)_FourNCLO_Four, (C_TwoH_Five)_FourNI, (C_Three
H₇)_FourNBr, (n-C_FourH₉) _FourNCLO_Four, (N-C_Four
H₉)_FourNI, (C_TwoH_Five)_FourN-maleate, (C_TwoH
_Five)_FourN-benzoate, (C_TwoH_Five)_FourN-phta
quaternary ammonium salts such as late, stearyl sulfone
Lithium oxide, lithium octyl sulfonate, dodecyl
Organic ion salts such as lithium benzene sulfonate;
These ionic compounds may be used alone or in combination of two or more.
It is possible to use a mixture of the above.

In particular, LiBF ₄ has a lower reactivity with water present in the electrolytic solution than the other fluorine-based lithium salts exemplified above, so that the generation of hydrofluoric acid causing corrosion of the electrode and the exterior material is reduced. Even when a thin material such as a metal-resin composite film is used as the exterior material for the purpose of reducing the weight and reducing the weight, a non-aqueous electrolyte battery having high durability can be obtained, so that it is preferable as an electrolyte salt.

Further, LiBF ₄ and LiN (C ₂ F ₅ S
By mixing and using a lithium salt having a perfluoroalkyl group such as O ₂ ) ₂ , the viscosity of the electrolytic solution can be further reduced, so that the low-temperature characteristics can be further improved. The concentration of the electrolyte salt in the liquid is 0.1 mol / l to 5 mol / l in order to reliably obtain a non-aqueous electrolyte battery having high battery characteristics.
And more preferably 1 mol / l to 2.5
mol / l.

As the positive electrode active material which is a main component of the positive electrode, it is desirable to use lithium-containing transition metal oxides, lithium-containing phosphates, lithium-containing sulfates, etc., alone or in combination. Examples of lithium-containing transition metal oxides include general formulas Li _y Co _1-x M _x O ₂ and Li _y Mn _2-x M _x
O ₄ (M is a metal of Group I to VIII (eg, Li, C
a, Cr, Ni, Fe, and Co), and the x value indicating the amount of dissimilar element substitution is effective up to the maximum amount that can be substituted, but is preferably 0 from the viewpoint of discharge capacity.
≦ x ≦ 1. For the y value indicating the amount of lithium, the maximum amount capable of reversibly using lithium is effective,
Preferably, 0 ≦ y ≦ 2 from the viewpoint of discharge capacity. ), But is not limited thereto.

Further, another positive electrode active material may be mixed with the above-mentioned lithium-containing compound, and the other positive electrode active material may be a Group I material such as CuO, Cu ₂ O, Ag ₂ O, CuS, and CuSO _4. metal compounds, TiS _2, SiO _2, IV group metal compound of SnO, _{etc., V 2 O 5, V 6} O 1 2, VO x, Nb 2 O 5, Bi
Group V metal compounds such as ₂ O ₃ and Sb ₂ O ₃ , CrO ₃ and Cr ₂ O
Group VI metal compound such as ₃ , ₃ , MoO ₃ , MoS ₂ , WO ₃ , SeO ₂ , Group VII metal compound such as MnO ₂ , Mn ₂ O ₃ , Fe ₂
O ₃ , FeO, Fe ₃ O ₄ , Ni ₂ O ₃ , NiO, CoO ₃ ,
Group VIII metal compound such as CoO or the general formula Li _x M
X ₂ , Li _x MN _y X ₂ (M and N are metals of Group I to VIII, X
Represents a chalcogen compound such as oxygen and sulfur. ) And the like, for example, a metal compound such as a lithium-cobalt-based composite oxide or a lithium-manganese-based composite oxide,
Examples include, but are not limited to, conductive polymer compounds such as disulfide, polypyrrole, polyaniline, polyparaphenylene, polyacetylene, and polyacene-based materials, and pseudo-graphite structured carbonaceous materials.

The negative electrode active material which is a main component of the negative electrode includes carbonaceous materials, metal oxides such as tin oxide and silicon oxide, and phosphorus or boron added to these materials for the purpose of improving the negative electrode characteristics. And modified materials. Among the carbonaceous materials, graphite has an operating potential very close to that of metallic lithium, so that self-discharge can be reduced when a lithium salt is employed as an electrolyte salt, and irreversible capacity in charge and discharge can be reduced, so that it is preferable as a negative electrode active material. . Further, in the present invention, since a non-aqueous electrolyte containing γ-butyrolactone and phenylene carbonate or a derivative thereof is used, γ-butyrolactone is decomposed on a negative electrode containing graphite as a main component at the time of charging, and the graphite is decomposed. Is less likely to be modified, and the above-mentioned advantageous properties of graphite can be reliably exhibited.

The analysis results of X-ray diffraction and the like of graphite that can be suitably used are shown below: Lattice spacing (d002) 0.333 to 0.350 nm Crystallite size La 20 in a-axis direction La 20 Nanometer or more Crystallite size in c-axis direction Lc 20 nanometer or more True density 2.00 to 2.25 g / cm3 In addition, graphite, metal oxides such as tin oxide and silicon oxide, phosphorus, boron, It is also possible to perform reforming by adding amorphous carbon or the like. In particular, by modifying the surface of graphite by the above-described method, it is possible to suppress the decomposition of the electrolyte and to improve the battery characteristics, which is desirable. Further, lithium metal, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and a lithium metal-containing alloy such as a wood alloy may be used in combination with graphite, Graphite or the like into which lithium has been inserted by chemical reduction can also be used as the negative electrode active material.

It is also possible to modify at least the surface layer portion of the powder of the positive electrode active material and the powder of the negative electrode active material with a material having good electron conductivity and ion conductivity, or a compound having a hydrophobic group. For example, materials having good electron conductivity such as gold, silver, carbon, nickel, and copper, lithium carbonate,
A material having good ion conductivity, such as boron glass or a solid electrolyte, or a material having a hydrophobic group such as silicone oil is coated by applying a technique such as plating, sintering, mechanofusion, vapor deposition, or baking.

The powder of the positive electrode active material and the powder of the negative electrode active material preferably have an average particle size of 100 μm or less. In particular, the powder of the positive electrode active material is desirably 10 μm or less for the purpose of improving the high output characteristics of the nonaqueous electrolyte battery. In order to obtain the powder in a predetermined shape, a pulverizer or a classifier is used. For example, mortar, ball mill, sand mill,
A vibration ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air jet mill, a sieve, and the like are used. At the time of pulverization, wet pulverization in which an organic solvent such as water or hexane coexists can be used. There are no particular limitations on the classification method, such as a sieve or a wind classifier,
Both dry and wet types are used as needed.

Although the positive electrode active material and the negative electrode active material have been described in detail above, the positive electrode and the negative electrode have a conductive agent, a binder, and a filler in addition to the above-mentioned active material, which is a main component. It may be contained as.

The conductive agent is not limited as long as it is an electron conductive material that does not adversely affect battery performance.
Natural graphite (flaky graphite, flaky graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon whisker, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) powder, A conductive material such as a metal fiber or a conductive ceramic material can be included as one type or a mixture thereof.

Among these, acetylene black is preferable as the conductive agent from the viewpoints of conductivity and coatability. The amount of the conductive agent to be added is preferably 1% by weight to 50% by weight, more preferably 2% by weight to 30% by weight based on the total weight of the positive electrode or the negative electrode. These mixing methods are physical mixing, and ideally, uniform mixing. Therefore, V-type mixer, S-type mixer, grinder, ball mill,
It is possible to mix a powder mixer such as a planetary ball mill in a dry or wet manner.

Examples of the binder include thermoplastic resins such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polypropylene; ethylene-propylene diene terpolymer (EPDM); and sulfonated EPD.
M, a polymer having rubber elasticity such as styrene-butadiene rubber (SBR) or fluororubber, or a polysaccharide such as carboxymethylcellulose can be used alone or as a mixture of two or more. Further, it is desirable that a binder having a functional group that reacts with lithium, such as a polysaccharide, be deactivated by, for example, methylation. The amount of the binder added is 1 to the total weight of the positive electrode or the negative electrode.
It is preferably 50% by weight, particularly preferably 2 to 30% by weight.

As the filler, any material may be used as long as it does not adversely affect battery performance. Usually, olefin polymers such as polypropylene and polyethylene, aerosil, zeolite, glass, carbon and the like are used. The amount of the filler is preferably 30% by weight or less based on the total weight of the positive electrode or the negative electrode.

The positive electrode and the negative electrode are prepared by mixing the active material, the conductive agent and the binder with an organic solvent such as N-methylpyrrolidone, toluene and the like. It is suitably prepared by coating on top and drying. Regarding the application method, for example, it is desirable to apply to any thickness and any shape using means such as roller coating such as an applicator roll, screen coating, a doctor blade method, spin coating, and a bar coder. It is not limited.

The current collector may be any electronic conductor that does not adversely affect the battery structure. For example, as the positive electrode current collector, aluminum, titanium,
In addition to stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, etc., the surface of aluminum, copper, etc. is coated with carbon, nickel, titanium, silver, etc. for the purpose of improving adhesion, conductivity and oxidation resistance. Can be used. As the current collector for the negative electrode, copper, nickel, iron, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc.
For the purpose of improving conductivity and oxidation resistance, a material obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver, or the like can be used. These materials can be oxidized on the surface.

Regarding the shape of the current collector, in addition to a foil shape, a film shape, a sheet shape, a net shape, a punched or expanded material, a lath body, a porous body, a foamed body, a fiber group formed body, and the like are used. Can be There is no particular limitation on the thickness.
〜500 μm is used. Among these current collectors, as the positive electrode, aluminum foil having excellent oxidation resistance is used, and as the negative electrode, copper foil, nickel foil, iron, which is stable in the reduction field and has excellent electrical conductivity, and is inexpensive. It is preferred to use foils, and alloy foils containing some of them.
Further, it is preferable that the foil has a rough surface roughness of 0.2 μm Ra or more, whereby the adhesion between the positive electrode active material or the negative electrode active material and the current collector becomes excellent. Therefore, it is preferable to use an electrolytic foil because of having such a rough surface. In particular, an electrolytic foil subjected to a napping treatment is most preferable.

As a separator for a non-aqueous electrolyte battery, it is preferable to use a porous film or a nonwoven fabric exhibiting excellent rate characteristics alone or in combination. Examples of the material constituting the separator for a non-aqueous electrolyte battery include polyolefin-based resins such as polyethylene and polypropylene; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; polyvinylidene fluoride; Fluoropropylene copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-fluoroethylene copolymer, fluorine Vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride - tetrafluoroethylene - hexafluoropropylene copolymer, vinylidene fluoride - ethylene - can be mentioned tetrafluoroethylene copolymer.

The porosity of the separator for a non-aqueous electrolyte battery is preferably 98% by volume or less from the viewpoint of strength. Further, the porosity is preferably 20% by volume or more from the viewpoint of charge and discharge characteristics.

The separator for a non-aqueous electrolyte battery uses a polymer gel composed of a polymer such as acrylonitrile, ethylene oxide, propylene oxide, methyl methacrylate, vinyl acetate, vinyl pyrrolidone, polyvinylidene fluoride, etc. and an electrolyte. Is also good.

Further, the separator for a non-aqueous electrolyte battery is as follows:
It is preferable to use a polymer gel in combination with the above-described porous membrane, nonwoven fabric, or the like, since the liquid retention of the electrolytic solution is improved.
That is, by forming a film coated with a lipophilic polymer having a thickness of several μm or less on the surface of the polyethylene microporous membrane and the microporous wall surface, and by holding the electrolytic solution in the micropores of the film,
The solvent-soluble polymer gels.

Examples of the solvent-philic polymer include polymers crosslinked with polyvinylidene fluoride, acrylate monomers having an ethylene oxide group or an ester group, epoxy monomers, monomers having an isocyanate group, and the like. Upon crosslinking, an actinic ray such as ultraviolet (UV) or electron beam (EB) can be used.

For the purpose of controlling the strength and physical properties, a physical property modifier within a range that does not hinder the formation of the crosslinked product can be blended with the solvent-philic polymer and used. Examples of the physical property modifier include inorganic fillers {metal oxides such as silicon oxide, titanium oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide and iron oxide, and metal carbonates such as calcium carbonate and magnesium carbonate}. And polymers {polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, and the like}. The amount of the physical property modifier is usually 50% by weight or less, preferably 20% by weight or less, based on the crosslinkable monomer.

As an example of the acrylate monomer, a bifunctional or higher functional unsaturated monomer is preferably exemplified.
More specific examples include bifunctional (meth) acrylate ｛ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, adipic acid / dineopentyl glycol ester di (meth) acrylate, and polyethylene glycol having a degree of polymerization of 2 or more. Di (meth) acrylate, polypropylene glycol di (meth) acrylate having a degree of polymerization of 2 or more, di (meth) acrylate of polyoxyethylene / polyoxypropylene copolymer, butanediol di (meth) acrylate, hexamethylene glycol di (meth) acrylate ) Acrylate, etc., trifunctional (meth)
Acrylate: trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, tri (meth) acrylate of glycerin ethylene oxide adduct, tri (meth) acrylate of glycerin propylene oxide adduct, glycerin ethylene oxide, propylene oxide addition Tri (meth) acrylate, etc.}, polyfunctional (meth) acrylate having 4 or more functional groups, pentaerythritol tetra (meth) acrylate,
And diglycerin hexa (meth) acrylate. These monomers can be used alone or in combination.

A monofunctional monomer may be added to the acrylate monomer for the purpose of adjusting physical properties and the like. Examples of the monofunctional monomer include unsaturated carboxylic acids ｛acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, vinylbenzoic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, methylenemalonic acid, Aconitic acid, etc., unsaturated sulfonic acid {styrene sulfonic acid, acrylamide-2-methylpropane sulfonic acid, etc.} or a salt thereof (Li salt, Na salt, K salt, ammonium salt,
Tetraalkylammonium salts, etc.) and also partially esterify these unsaturated carboxylic acids with C1-C18 aliphatic or alicyclic alcohols, alkylene (C2-C4) glycols, polyalkylene (C2-C4) glycols, etc. (Methylmalate, monohydroxyethylmalate, etc.) and partially amidated with ammonia and primary or secondary amines (maleic acid monoamide, N-methylmaleic acid monoamide, N, N-diethylmaleic acid) Monoamide), (meth) acrylic acid ester [C1-C18 aliphatic (methyl, ethyl, propyl, butyl, 2-ethylhexyl, stearyl, etc.)
Ester of alcohol and (meth) acrylic acid, or alkylene (C2-C4) glycol (ethylene glycol, propylene glycol, 1,4-butanediol, etc.) and polyalkylene (C2-C4) glycol (polyethylene glycol, polypropylene glycol) With (meth) acrylamide or N-substituted (meth) acrylamide [(meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, etc.]; vinyl ester or Allyl ester [vinyl acetate, allyl acetate, etc.]; vinyl ether or allyl ether [butyl vinyl ether, dodecyl allyl ether, etc.]; unsaturated nitrile compound [(meth) acrylonitrile, crotonnitrile, etc.]; Saturated alcohols [(meth) allyl alcohol]; unsaturated amines [(meth) allylamine, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate];
Heterocycle-containing monomer [N-vinylpyrrolidone, vinylpyridine, etc.]; olefinic aliphatic hydrocarbon [ethylene,
Propylene, butylene, isobutylene, pentene, (C
6-C50) α-olefins, etc.]; olefin-based alicyclic hydrocarbons [cyclopentene, cyclohexene, cycloheptene, norbornene, etc.]; olefin-based aromatic hydrocarbons [styrene, α-methylstyrene, stilbene, etc.];
Unsaturated imide [maleimide etc.]; halogen-containing monomer [vinyl chloride, vinylidene chloride, vinylidene fluoride, hexafluoropropylene etc.] and the like.

Examples of the epoxy monomer include glycidyl ethers such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, brominated bisphenol A diglycidyl ether, phenol novolac glycidyl ether, cresol novolac glycidyl ether, and glycidyl esters. Glycidyl hexahydrophthalate, glycidyl dimer, etc., glycidylamines, triglycidyl isocyanurate, tetraglycidyl diaminophenylmethane, etc., linear aliphatic epoxides, epoxidized polybutadiene, epoxidized soybean oil, etc.,
Alicyclic epoxides {3,4 epoxy-6 methylcyclohexylmethyl carboxylate, 3,4 epoxy cyclohexylmethyl carboxylate, etc.}; These epoxy resins can be used alone or after being cured by adding a curing agent.

Examples of the curing agent include aliphatic polyamines such as diethylene triamine, triethylene tetramine,
3,9- (3-aminopropyl) -2,4,8,10-
Tetrooxaspiro [5,5] undecane, etc., aromatic polyamines, such as meta-xylene diamine, diaminophenylmethane, etc., polyamides, such as dimer acid polyamide, etc., acid anhydrides, phthalic anhydride, tetrahydromethyl phthalic anhydride. , Hexahydrophthalic anhydride, trimellitic anhydride, methylnadic anhydride, phenols such as phenol novolak, polymercaptans such as polysulfide, tertiary amines tris (dimethylaminomethyl) phenol, 2-ethyl-4 -Methylimidazole, etc.}, Lewis acid complex {boron trifluoride / ethylamine complex, etc.} and the like.

Examples of the monomer having an isocyanate group include toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4 (2,2,4) -trimethyl-hexamethylene diisocyanate, and p-phenylene diisocyanate. 4,4′-dicyclohexylmethane diisocyanate, 3,3′-dimethyldiphenyl 4,4′-diisocyanate, dianisidine diisocyanate, m-xylene diisocyanate, trimethyl xylene diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, trans
-1,4-cyclohexyl diisocyanate, lysine diisocyanate and the like.

In crosslinking the isocyanate group-containing monomer, polyols and polyamines [bifunctional compounds {water, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, etc.}, trifunctional compounds} glycerin, trimethylolpropane, 1,4,6-hexanetriol, triethanolamine, etc., tetrafunctional compound, pentaerythritol, ethylenediamine, tolylenediamine, diphenylmethanediamine, tetramethylolcyclohexane,
Methyl glucoside, etc.｝ pentafunctional compound ｛2,2,6,6
-Tetrakis (hydroxymethyl) cyclohexanol, diethylenetriamine and the like {, 6-functional compound {sorbitol, mannitol, dulcitol, etc.}, 8-functional compound {sucrose, etc.}], and polyether polyols {propylene oxide and / or the polyol or polyamine) An ethylene oxide adduct {, a polyester polyol [condensation product of the polyol and a polybasic acid {adipic acid, o, m, p-phthalic acid, succinic acid, azelaic acid, sebacic acid, ricinoleic acid};
Compounds having active hydrogen can be used in combination, such as polycaprolactone polyol {poly-ε-caprolactone, etc.}, polycondensates of hydroxycarboxylic acids, etc.].

In the crosslinking reaction, a catalyst can be used in combination. Examples of the catalyst include organotin compounds, trialkylphosphines, amines [monoamines {N, N-dimethylcyclohexylamine, triethylamine, etc.}, cyclic monoamines {pyridine, N-methylmorpholine, etc.}, diamines} N, N, N ', N'
-Tetramethylethylenediamine, N, N, N ', N'
-Tetramethyl 1,3-butanediamine etc., triamines {N, N, N ', N'-pentamethyldiethylenetriamine etc.}, hexamines {N, N, N'N'-tetra (3-dimethylaminopropyl) ) -Methanediamine, etc., cyclic polyamines, diazabicyclooctane (D
ABCO), N, N'-dimethylpiperazine, 1,2-
Dimethylimidazole, 1,8-diazabicyclo (5,
4,0) undecene-7 (DBU) and the like, and salts thereof.

In the non-aqueous electrolyte battery according to the present invention, for example, the electrolyte is injected before or after laminating the separator for a non-aqueous electrolyte battery and the positive electrode and the negative electrode.
It is suitably manufactured by sealing with an exterior material. Further, in a non-aqueous electrolyte battery in which a positive electrode and a negative electrode are wound around a power generating element stacked with a non-aqueous electrolyte battery separator interposed therebetween, the electrolyte is injected into the power generating element before and after the winding. Is preferred. As the liquid injection method, it is possible to inject liquid at normal pressure, but a vacuum impregnation method or a pressure impregnation method can also be used.

From the viewpoint of reducing the weight of the nonaqueous electrolyte battery, a thin material is preferable as the exterior material. For example, a metal-resin composite film in which a metal foil is sandwiched between resin films is preferable. Specific examples of the metal foil include aluminum,
Iron, nickel, copper, stainless steel, titanium, gold, silver, etc.
There is no limitation as long as the foil has no pinhole, but a lightweight and inexpensive aluminum foil is preferred. As the resin film on the outside of the battery, a resin film having excellent piercing strength such as a polyethylene terephthalate film or a nylon film can be used, and as the resin film on the inside of the battery, a polyethylene film or a nylon film can be used. It is preferable to use a film that has a solvent resistance.

[0051]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. (Example) A nonaqueous electrolyte battery of an example was manufactured according to the following procedures (a) to (c).

(A) The positive electrode was prepared as follows. After mixing LiCoO ₂ as a positive electrode active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder at a weight ratio of 90: 5: 5, N- as a solvent was used.
A positive electrode slurry of the above material was prepared using methylpyrrolidone. The obtained slurry was used as a positive electrode current collector at 20 μm.
The N-methylpyrrolidone was removed by coating on both sides of an aluminum foil and drying. This positive electrode plate was pressed by a roll press to obtain a positive electrode.

(B) The negative electrode was prepared as follows. Graphite having an Lc of 100 nm or more as a negative electrode active material and styrene butadiene rubber (SB) as a binder
R) and carboxymethylcellulose (CMC)
After mixing at a weight ratio of 7: 2: 1, a negative electrode slurry of the above material was prepared using purified water as a solvent. The obtained slurry was used as a negative electrode current collector and had a rough surface roughness of 0.3 μm Ra.
Was applied to both sides of an electrolytic copper foil, and dried to remove N-methylpyrrolidone. This negative electrode plate was pressed by a roll press to obtain a negative electrode.

(C) Preparation of Nonaqueous Electrolyte Battery of Example 1 The positive electrode and the negative electrode obtained in the above (a) and (b) were combined with a nonwoven fabric made of polyethylene as a nonaqueous electrolyte battery separator (with a basis weight of 10 g / m 2). ² and a thickness of 100 μm), followed by aluminum terminals (width 5 mm, thickness 10 μm).
0 μm) (positive electrode terminal) was connected to the positive electrode current collector, and the nickel terminal (5 mm width, 100 μm thickness) (negative electrode terminal) was connected to the negative electrode current collector by electric resistance welding. This laminated body is formed into a cylindrical metal-resin composite film (resin outside the battery,
(The metal foil and the battery inside resin are polyethylene terephthalate, aluminum foil, and modified polypropylene, respectively), and then 20 parts by weight of lithium tetrafluoroborate (LiBF ₄ ) and γ-butyrolactone A non-aqueous electrolyte obtained by mixing 80 parts by weight and 5 parts by weight of phenylene carbonate was vacuum-injected into the exterior material (13).
33 Pa) and vacuum sealing (1333 Pa) to produce the non-aqueous electrolyte battery of Example 1.

(D) Preparation of Non-Aqueous Electrolyte Battery of Example 2 Instead of phenylene carbonate, 4-methyl-benzo [1,
3] A non-aqueous electrolyte battery of Example 2 was produced in the same manner as in Example 1, except that dioxyzol-2-one was used.

(E) Preparation of Nonaqueous Electrolyte Battery of Comparative Example 1 20 parts by weight of lithium tetrafluoroborate (LiBF ₄ ) and γ
A non-aqueous electrolyte battery of Comparative Example 1 was produced in the same manner as in the non-aqueous electrolyte battery of the above-described example, except that a non-aqueous electrolyte mixed with 80 parts by weight of butyrolactone was used.

(F) Preparation of Nonaqueous Electrolyte Battery of Comparative Example 2 A nonaqueous electrolyte obtained by mixing 20 parts by weight of lithium tetrafluoroborate (LiBF ₄ ), 80 parts by weight of propylene carbonate, and 5 parts by weight of phenylene carbonate was used. A non-aqueous electrolyte battery of Comparative Example 2 was produced in the same manner as in the non-aqueous electrolyte battery of the above-described embodiment except that the battery was used.

(Performance Test of Nonaqueous Electrolyte Battery) Using the nonaqueous electrolyte battery of the example and the nonaqueous electrolyte battery of the comparative example, the discharge capacity at 20 ° C. and the discharge capacity at −20 ° C. were measured. . Charging is 4.1 at 20 ° C
V, 5 hour rate (0.2 C), constant current constant voltage charging for 7 hours, and discharge at a final voltage of 2.7 V, 5 hour rate (0.2 C) at 20 ° C. and −20 ° C., respectively. Performed with current. The energy density was evaluated by “discharge capacity at 20 ° C.”, and the low-temperature characteristics were evaluated by “ratio of discharge capacity at −20 ° C. to discharge capacity at 20 ° C.”.
Table 1 shows the results.

[0059]

[Table 1]

As shown in Table 1, the non-aqueous electrolyte batteries of Examples 1 and 2 were compared with the non-aqueous electrolyte batteries of Comparative Examples 1 and 2 in terms of “discharge capacity at 20 ° C.” The ratio of the discharge capacity at −20 ° C. to the discharge capacity at 20 ° C. ”was high, and it was confirmed that the battery was a nonaqueous electrolyte battery having both good low-temperature characteristics and high energy density.

On the other hand, the nonaqueous electrolyte battery of Comparative Example 1
The discharge capacity at 0 ° C. was low, and a high energy density was not obtained.
It is considered that butyrolactone was decomposed and the reversible capacity was reduced.

The non-aqueous electrolyte battery of Comparative Example 2
The ratio of the discharge capacity at −20 ° C. to the discharge capacity at 0 ° C. ”was low, and the low-temperature characteristics were insufficient. The non-aqueous solvent of the non-aqueous electrolyte was composed of propylene carbonate and phenylene carbonate. Also, it is considered that the viscosity was higher than that of the non-aqueous electrolyte battery of the example because it did not contain γ-butyrolactone.

[0063]

As described above, according to the present invention, as described in claim 1, the non-aqueous electrolyte contains γ-butyrolactone and phenylene carbonate or a derivative thereof as non-aqueous solvents. By doing so, it is possible to ensure ionic conduction without increasing the viscosity of the electrolytic solution even at low temperatures, and to sufficiently suppress the decomposition of γ-butyrolactone on the negative electrode during charging to sufficiently charge the battery. As a result, it is possible to provide a non-aqueous electrolyte battery having both good low-temperature characteristics and high energy density.

According to the present invention, since the negative electrode active material is graphite as described in claim 2, the use of a lithium salt as the electrolyte salt makes it possible to reduce self-discharge and reduce charge and discharge. A non-aqueous electrolyte battery with small irreversible capacity can be provided.

According to the present invention, the electrolyte salt is lithium tetrafluoroborate (Li).
BF ₄ ) has low reactivity with water present in the electrolytic solution and generates a small amount of hydrofluoric acid which causes corrosion of electrodes and exterior materials. Even when a thin material such as a composite film is used, a non-aqueous electrolyte battery having high durability can be provided.

Claims (3)

[Claims] At least one of a positive electrode having a positive electrode active material as a main component, a negative electrode having a negative electrode active material as a main component, and a non-aqueous electrolyte containing an electrolyte salt in a non-aqueous solvent. In the nonaqueous electrolyte battery, the nonaqueous electrolyte solution contains γ-butyrolactone and phenylene carbonate or a derivative thereof as the nonaqueous solvent. 2. The non-aqueous electrolyte battery according to claim 1, wherein the negative electrode active material is graphite. 3. The non-aqueous electrolyte battery according to claim 1, wherein the electrolyte salt is lithium tetrafluoroborate (LiBF ₄ ).