JP2003168477A - Non-aqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery, which combines a good low-temperature performance, high energy density, and the outstanding high- temperature preservation ability. <P>SOLUTION: In the non-aqueous electrolyte battery constituted by at least, a positive electrode, which uses a positive-electrode active material as a main composition component, a negative electrode, which uses a negative-electrode carbonaceous material as the main composition component, and a non-aqueous electrolyte, the above negative-electrode carbonaceous material contains 5% or more of a rhombohedral system structure, and the above non-aqueous electrolyte contains at least carbonate, in which has double bonds of carbon and carbon. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte battery, and more particularly to a negative electrode carbonaceous material and a non-aqueous electrolyte used in a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, non-aqueous electrolyte batteries, especially lithium secondary batteries, have been used as power sources for mobile devices such as mobile phones, PHS (simple mobile phones), and small computers, power storage power sources,
It is attracting attention as a power source for electric vehicles. The lithium secondary battery has a problem that the discharge performance at a low temperature is not sufficient, and there has been a strong demand for a lithium secondary battery that exhibits good low-temperature performance. There has also been a demand for batteries that are small, lightweight, and have high energy density.

A lithium secondary battery is generally composed of a positive electrode containing a positive electrode active material as a main constituent, a negative electrode, and a non-aqueous electrolyte. A lithium-containing transition metal oxide or the like is used as the positive electrode active material, a carbonaceous material typified by graphite having a hexagonal structure is used as the negative electrode material, and lithium hexafluorophosphate (LiPF 6) is used as the non-aqueous electrolyte. _{The one in which} an electrolyte salt such as ₆ ) is dissolved in a non-aqueous solvent such as ethylene carbonate is widely used.

However, since the ethylene carbonate used as the non-aqueous solvent has a low melting point and the non-aqueous electrolyte easily coagulates at a low temperature, the low temperature performance of the lithium secondary battery has been poor. Therefore, in place of ethylene carbonate, a method of using propylene carbonate having a lower melting point as a non-aqueous solvent is known, but particularly when graphite having a high graphitization rate is used as the negative electrode carbonaceous material, propylene carbonate is used during charging. However, since the side reaction such as decomposition on the graphite negative electrode is severe, charging cannot be performed sufficiently, which causes a great decrease in battery performance.

As a means for solving this problem, Japanese Unexamined Patent Publication No.
0-97870 discloses an attempt to suppress delamination of graphite by using graphite having a rhombohedral system structure and to reduce irreversible capacity in a battery using a non-aqueous electrolyte containing propylene carbonate. ing. Also,
Simon, B; Flandrois.S; Fevrier-Bouvier, A; Biensan, P.He
xagonal vs Rhombohedral Graphite: The Effect of C
rystal Structure onthe Electrochemical Intercalati
on on Lithium Ion.Mol.Cryst.Liq.Cryst.vol.310,199
8, p.333-340., In addition to the description of the same effect as above, a carbonaceous material containing a rhombohedral structure in graphite at an arbitrary ratio of several% to several tens% is synthesized. The method is described.

However, although these techniques have the effect of reducing the irreversible capacity, they have not been satisfactory improvements.

On the other hand, in JP-A-11-111297, in order to prevent decomposition of the electrolytic solution, the proportion of crystals having a rhombohedral crystal structure in the crystal structure of the graphitized product does not exceed 30%. It is stated that it is necessary to do so. In addition, the first solvent is used as the electrolyte.
Ethylene carbonate as a solvent and a solvent generally known as a second solvent, for example, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (P
Carbonates having no carbon-carbon double bond such as C) are mentioned.

Further, Japanese Unexamined Patent Publication (Kokai) No. 11-283667 describes that vinylene carbonate is used in combination in order to prevent decomposition of propylene carbonate when a graphite-based carbonaceous material is used. Further, it is described that the addition amount of vinylene carbonate needs to be 5% or more. This is because if the added amount is less than 5%, the battery capacity will be reduced.

[0009]

The present invention has been made in view of the above problems, and an object thereof is to provide a non-aqueous electrolyte battery having both excellent low temperature performance and high energy density. is there.

[0010]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have made earnest studies and, as a result, have used a graphite having a rhombohedral system structure and further used a non-aqueous solvent constituting a non-aqueous electrolyte. It has been found that a non-aqueous electrolyte battery having both a good low temperature performance and a high energy density can be obtained surprisingly by making the above specific, and the present invention has been completed. That is, the technical configuration of the present invention and its effects are as follows. However, the mechanism of action includes estimation, and its correctness does not limit the present invention.

That is, the non-aqueous electrolyte battery according to claim 1 is composed of at least a positive electrode having a positive electrode active material as a main constituent, a negative electrode having a negative electrode carbonaceous material as a main constituent, and a non-aqueous electrolyte. In the non-aqueous electrolyte battery according to the present invention, the negative electrode carbonaceous material contains 5% or more of a rhombohedral structure, and the non-aqueous electrolyte contains at least a carbonate having a carbon-carbon double bond. .

The non-aqueous electrolyte battery according to a second aspect of the invention is characterized in that the non-aqueous electrolyte contains propylene carbonate.

That is, the most general structure of graphite is a hexagonal structure, and the carbon network plane has an ABAB type laminated structure in which the B layer close to the A layer is displaced. On the other hand, as another thermodynamically metastable state, there is a rhombohedral crystal structure, which is an ABCABC type laminated structure.

When graphite having a hexagonal structure is used for the negative electrode and propylene carbonate is used as the solvent for the electrolyte, a protective film (SEI; Solid Electrolyte) formed when lithium ions are electrochemically intercalated
Interface) layer was not sufficiently formed, the irreversible capacity was large, and the battery performance was not good. On the other hand, when graphite containing a rhombohedral structure was used for the negative electrode, and a carbonate having a carbon-carbon double bond was combined as a solvent for the non-aqueous electrolyte, it was surprisingly found that the irreversible capacity was greatly reduced. I found it effective. This effect was recognized as a specific phenomenon when a carbonate having a carbon-carbon double bond was used. Carbonates having a carbon-carbon double bond are susceptible to reduction,
Since the SEI layer is formed on the surface of the carbonaceous material having a particularly active rhombohedral system structure, it is considered to have the effect of preventing reductive decomposition of other non-aqueous solvent and greatly reducing the irreversible capacity.

The above-mentioned effects are particularly remarkable when combined with propylene carbonate. Since propylene carbonate has a low viscosity and an excellent dielectric constant, it is possible to secure sufficient ionic conductivity even at low temperatures without increasing the viscosity of the non-aqueous electrolyte. In addition, since the graphite having the rhombohedral structure and the carbonate having a carbon-carbon double bond are contained, the decomposition of propylene carbonate on the negative electrode during charging can be reliably suppressed, and thus the charging is sufficiently performed. be able to. Therefore, a non-aqueous electrolyte battery having both good low temperature performance and high energy density can be obtained.

Even more surprisingly, when a carbonate having a carbon-carbon double bond and a propylene carbonate are used in combination, even if the propylene carbonate is contained in the non-aqueous solvent in an amount of about 80% by volume, it becomes extremely non-aqueous. It was found that a remarkable effect was exhibited without causing decomposition of the electrolyte.

The non-aqueous electrolyte battery according to the third aspect is characterized in that the carbonate having a carbon-carbon double bond is vinylene carbonate.

Among the carbonates having a double bond, vinylene carbonate is desirable because it is one of the carbonates most susceptible to reduction and less susceptible to oxidative decomposition.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be illustrated below, but the present invention is not limited to the following embodiments.

The non-aqueous electrolyte battery according to the present invention comprises a positive electrode containing a positive electrode active material as a main constituent, a negative electrode containing a carbonaceous material as a main constituent, and a non-aqueous electrolyte containing an electrolyte salt in a non-aqueous solvent. And a separator is generally provided between the positive electrode and the negative electrode.

The carbonate having a carbon-carbon double bond contained in the non-aqueous solvent of the non-aqueous electrolyte includes vinylene carbonate (VC), styrene carbonate (SC),
Examples thereof include catechol carbonate, vinylethylene carbonate, 1-phenylvinylene carbonate, and 1,2-diphenylvinylene carbonate, but are not limited thereto. Further, a carbonate having a carbon-carbon double bond is not excellent in oxidation resistance as compared with a carbonate having no carbon-carbon double bond, and therefore the addition amount is preferably less than 5% by volume of the non-aqueous solvent. . Further, in order to form a sufficient SEI layer on the surface, 0.5% by volume or more of the non-aqueous solvent is desirable.

As other non-aqueous solvents, those generally proposed for use in lithium batteries and the like can be used. Particularly, propylene carbonate (PC) belongs to the third petroleum group, has a high boiling point, has a high flash point and can improve safety, and has a low melting point, so that it is also possible to improve low temperature characteristics, which is desirable. . According to the configuration of the present invention, the irreversible capacity does not significantly increase even if propylene carbonate is contained. Even when propylene carbonate is contained in the non-aqueous solvent of the non-aqueous electrolyte in an amount of 40 vol% or more, the irreversible capacity does not increase, so that the non-aqueous electrolyte does not coagulate even at low temperatures and ion conduction is prevented. You can be sure. Therefore, a non-aqueous electrolyte battery having both high low temperature characteristics and high energy density can be obtained. Furthermore, although propylene carbonate can be charged and discharged even if it is contained in the non-aqueous solvent of the non-aqueous electrolyte in an amount of 60% by volume or more, the irreversible capacity tended to increase slightly, so the proportion of propylene carbonate was 60%
It is desirable to be less than.

Among the other non-aqueous solvents, other than propylene carbonate, ethylene carbonate (E
C), cyclic carbonic acid esters such as butylene carbonate, chloroethylene carbonate; γ-butyrolactone, γ
-Cyclic esters such as valerolactone; chain carbonates such as dimethyl carbonate, diethyl carbonate (DEC) and methyl ethyl carbonate; methyl formate,
Chain esters such as methyl acetate and methyl butyrate; tetrahydrofuran or its derivatives; 1,3-dioxane, 1,
4-dioxane, 1,2-dimethoxyethane, 1,4-
Ethers such as dibutoxyethane and methyl diglyme;
One or more kinds of nitriles such as acetonitrile and benzonitrile; dioxolane or a derivative thereof; sulfolane, sultone or a derivative thereof can be mixed, but the mixture is not limited thereto. Among these, non-aqueous solvents having a vapor pressure of 1000 Pa or less, more preferably 500 Pa or less, such as propylene carbonate, ethylene carbonate, γ-butyrolactone, etc., are desirable because they have a small swelling during storage at high temperature.

As the electrolyte salt, for example, LiCl
O_Four, LiBF_Four, LiAsF₆, LiPF₆, LiSC
N, LiBr, LiI, Li₂SO_Four, Li₂B_TenC
l_Ten, NaClO_Four, NaI, NaSCN, NaBr,
KClO_Four, KSCN, Lithium (Li), Natriu
Inorganic ion containing one of sodium (Na) or potassium (K)
Salt, LiCF₃SO₃, LiN (CF₃SO₂)₂, LiN
(C₂F_FiveSO₂)₂, (CH₃)_FourNBF_Four, (CH₃)_FourN
Br, (C₂H_Five)_FourNClO_Four, (C₂H_Five)_FourNI, (C₃
H₇) _FourNBr, (n-C_FourH₉)_FourNClO_Four, (N-C_Four
H₉)_FourNI, (C₂H_Five)_FourN-maleate, (C₂H
_Five)_FourN-benzoate, (C₂H_Five)_FourN-phta
Quaternary ammonium salt such as late, stearyl sulfone
Lithium oxide, lithium octyl sulfonate, dodecylbe
Examples include organic ionic salts such as lithium benzenesulfonate.
These ionic compounds may be used alone or in combination of two or more.
It is possible to mix and use the above.

Among these salts, LiPF ₆ is preferable because it has excellent dissociation properties and excellent conductivity.

Although LiBF ₄ has a lower dissociation degree and conductivity than LiPF ₆ , it has a low reactivity with water present in the electrolytic solution, so that the water management of the electrolytic solution can be simplified. It is preferable because it is possible and the manufacturing cost can be reduced. Further, a non-aqueous electrolyte battery that has a low degree of generation of hydrofluoric acid that causes corrosion of electrodes and exterior materials and has high durability even when a thin material of 200 μm or less such as a metal resin composite film is used as the exterior material. Is preferable in that

Alternatively, LiPF ₆ or LiBF ₄ and Li
When used in combination with a lithium salt having a perfluoroalkyl group such as N (C ₂ F ₅ SO ₂ ) ₂ , it is possible to further reduce the viscosity of the electrolytic solution and to improve the storage stability. Is preferred.

The concentration of the electrolyte salt in the non-aqueous electrolyte is
In order to reliably obtain a non-aqueous electrolyte battery having high battery characteristics, it is preferably 0.1 mol / l to 5 mol / l, more preferably 1 mol / l to 2.5 mol / l.

As the positive electrode active material which is the main constituent of the positive electrode
Include lithium-containing transition metal oxides and lithium-containing phosphorus.
Acid salt, lithium-containing sulfate, etc., alone or in combination
Is desirable. Lithium-containing transition metal oxide
The general formula Li_yCo_1-xM _xO₂, Li_yNi_1-xM
_xO₂, Li_yMn_2-xM_XO_Four(M is from I to VIII
Of metals (eg, Li, Ca, Cr, Ni, Fe, Co
X value indicating the amount of substitution of different elements)
Is effective up to the maximum amount that can be replaced, but is preferable
Or, in terms of discharge capacity, 0 ≦ x ≦ 1. Also, Richiu
For the y value, which indicates the amount of lithium, use lithium reversibly
The maximum amount is effective, preferably 0 from the viewpoint of discharge capacity.
≦ y ≦ 2. ), But is not limited to these
Not something.

Further, other positive electrode active material may be mixed with the lithium-containing compound, and as the other positive electrode active material, CuO, Cu ₂ O, Ag ₂ O, CuS, CuSO ₄ or the like can be used. IV of metal compounds, TiS ₂ , SiO ₂ , SnO, etc.
Group metal compound, V ₂ O ₅ , V ₆ O ₁₂ , VO _x , Nb ₂ O ₅ , B
Group V metal compounds such as i ₂ O ₃ and Sb ₂ O ₃ , CrO ₃ and Cr ₂
Group VI metal compounds such as O ₃ , MoO ₃ , MoS ₂ , WO ₃ , and SeO ₂ , Group VII metal compounds such as MnO ₂ , Mn ₂ O ₃ , Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , and Ni ₂ O ₃ , NiO,
Group VIII metal compounds such as CoO ₃ and CoO, or general formulas Li _x MX ₂ , Li _x MN _y X ₂ (M and N are I to VI
Group II metal, X represents a chalcogen compound such as oxygen or sulfur. ) Or the like, for example, a metal compound such as a lithium-cobalt-based composite oxide or a lithium-manganese-based composite oxide, and a conductive high material such as disulfide, polypyrrole, polyaniline, polyparaphenylene, polyacetylene, or polyacene-based material. Examples thereof include molecular compounds and pseudo-graphite structure carbonaceous materials, but are not limited to these.

Among the negative electrode carbonaceous materials, which are the main constituents of the negative electrode, graphite has an operating potential very close to that of metallic lithium, so that it is possible to reduce self-discharge when a lithium salt is used as the electrolyte salt and to reduce charge and discharge. It is preferable as a negative electrode carbonaceous material because it can reduce the irreversible capacity. Graphite crystals include the well-known hexagonal system and others belonging to the rhombohedral system. In particular, the rhombohedral graphite has a wide range of solvent selectivity in the non-aqueous electrolyte, and even when a non-aqueous solvent such as propylene carbonate is used, delamination is suppressed and excellent charge-discharge efficiency is exhibited. desirable.

The results of analysis by X-ray diffraction of rhombohedral graphite that can be preferably used are shown below: Lattice constant a ₀ = 0.3635 nm, α = 39.4
9 °

Most of natural graphite and artificial graphite are hexagonal, but some natural graphite and artificial graphite heat-treated at very high temperature have several% of rhombohedral structure.
In addition, there is an increase from the hexagonal system to the rhombohedral system due to crushing and grinding. In particular, graphite in which the surface of graphite particles contains a large amount of rhombohedral system and the interior of particles contains a large amount of hexagonal system is most desirable in terms of high capacity, solvent resistance, manufacturing process and the like.

Here, a method of calculating the rhombohedral crystal system contained in the entire graphite crystal, which is described in Japanese Patent Laid-Open No. 2000-348727, will be described. The peak area of the (101) diffraction line attributed to the rhombohedral crystal measured by the X-ray wide-angle diffraction method is r (101), and the peak area of the (101) diffraction line attributed to the hexagonal crystal measured in the same manner. h (101)
Then, the abundance ratio R% of rhombohedral crystals in the entire graphite crystal is calculated by (Equation 1).

[0035]

[Formula 1]

Rhombohedral graphite is a negative electrode carbonaceous material.
% Or more is preferable because it has an effect of greatly reducing the irreversible capacity in the initial charge and discharge, and in order to obtain a more remarkable effect, it is preferable that the content be 15% or more.

In addition to rhombohedral graphite, the negative electrode material is modified by adding hexagonal graphite, metal oxides such as tin oxide and silicon oxide, phosphorus, boron and amorphous carbon. You may do quality. Particularly, by modifying the surface of the negative electrode material by the above method, it is possible to further suppress the decomposition of the non-aqueous electrolyte and improve the battery characteristics, which is desirable. Further, with respect to graphite, lithium metal, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-
It is also possible to use gallium, a lithium metal-containing alloy such as a wood alloy, or the like, or graphite into which lithium is inserted by electrochemical reduction in advance, or the like, can be used as the negative electrode 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 material with a material having good electron conductivity or ion conductivity, or a compound having a hydrophobic group. For example, substances having good electron conductivity such as gold, silver, carbon, nickel, and copper, substances having good ion conductivity such as lithium carbonate, boron glass, and solid electrolyte,
Alternatively, a material having a hydrophobic group such as silicone oil may be 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 carbonaceous material preferably have an average particle size of 100 μm or less. In particular, the powder of the positive electrode active material is preferably 10 μm or less for the purpose of improving the high output characteristics of the non-aqueous electrolyte battery. A crusher or a classifier is used to obtain the powder in a predetermined shape. For example, mortar, ball mill, sand mill, vibrating ball mill, planetary ball mill, jet mill,
A counter jet mill, a swirling air flow type jet mill, a sieve or the like is used. Wet grinding in which water or an organic solvent such as hexane coexists may be used during grinding. The classification method is not particularly limited, and a sieve, an air classifier, or the like may be used in both dry and wet methods as needed.

The positive electrode and the negative electrode may contain a conductive agent, a binder and a filler as other constituent components in addition to the main constituent components.

The conductive agent is not limited as long as it is an electron conductive material that does not adversely affect the battery performance, but usually,
Natural graphite (scaly graphite, flake graphite, earth graphite, etc.), artificial graphite, carbon black, acetylene black, Ketjen black, carbon whiskers, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) powder, A conductive material such as a metal fiber or a conductive ceramic material may be contained as one kind or a mixture thereof.

Of these, acetylene black is preferable as the conductive agent from the viewpoint of electron conductivity and coatability. The amount of the conductive agent added is preferably 1% by weight to 50% by weight, and particularly 2% by weight to 30% by weight based on the total weight of the positive electrode or the negative electrode.
Weight percent is preferred. These mixing methods are physical mixing, and ideally, they are homogeneous mixing. Therefore, powder type mixers such as V type mixer, S type mixer, grinding machine, ball mill and planetary ball mill are dry type,
Alternatively, it is possible to mix them by a wet method.

The binder is usually a thermoplastic resin such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene or polypropylene, ethylene-propylene diene terpolymer (EPDM), sulfonated EPD.
Polymers having rubber elasticity such as M, styrene-butadiene rubber (SBR) and fluororubber, polysaccharides such as carboxymethyl cellulose and the like can be used as one kind or as a mixture of two or more kinds. In addition, it is desirable that the binder having a functional group that reacts with lithium such as a polysaccharide is deactivated by, for example, methylating. The amount of the binder added is 1 to 50 with respect to the total weight of the positive electrode or the negative electrode.
Weight% is preferable, and 2-30 weight% is especially preferable.

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

For the positive electrode and the negative electrode, the active material, the conductive agent, and the binder are mixed with an organic solvent such as N-methylpyrrolidone and toluene, and the resulting mixed liquid is used as a current collector described in detail below. It is suitably prepared by applying it on the surface and drying it. For the coating method, for example, roller coating such as applicator roll, screen coating, doctor blade method, spin coating,
It is desirable to apply it in an arbitrary thickness and an arbitrary shape by using a means such as a bar coater, but it is not limited thereto.

The current collector may be any electron conductor as long as it does not adversely affect the constructed battery. For example, as the current collector for the positive electrode, aluminum, titanium,
In addition to stainless steel, nickel, baked carbon, conductive polymers, conductive glass, etc., the surface of aluminum, copper, etc. is carbon, nickel, titanium, silver, etc. for the purpose of improving adhesion, conductivity, and oxidation resistance. The product treated with can be used. As the negative electrode current collector, in addition to copper, nickel, iron, stainless steel, titanium, aluminum, baked carbon, conductive polymer, conductive glass, Al-Cd alloy, adhesiveness,
For the purpose of improving conductivity and resistance to reduction, a material obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver or the like can be used. It is also possible to oxidize the surface of these materials.

With respect to the shape of the current collector, in addition to the foil shape, a film shape, a sheet shape, a net shape, a punched or expanded material, a lath body, a porous body, a foam body, a fiber group forming body, or the like is used. To be There is no particular limitation on the thickness, but 1
Those having a thickness of up to 500 μm are used. Among these current collectors, the positive electrode is an aluminum foil having excellent oxidation resistance, and the negative electrode is a stable copper foil in a reducing field and has excellent electrical conductivity, and an inexpensive copper foil, nickel foil, or iron. Preference is given to using foils and alloy foils containing parts thereof. Furthermore, it is preferable that the foil has a rough surface with a surface roughness of 0.2 μmRa or more, and thereby the adhesion between the positive electrode active material or the negative electrode carbonaceous material and the current collector will be excellent. Therefore, it is preferable to use the electrolytic foil because it has such a rough surface. In particular, an electrolytic foil that has been treated with a hook is most preferable. Further, when both sides of the current collector are used, it is desirable that the surface roughness thereof be equal or almost equal.

As the separator for a non-aqueous electrolyte battery, it is preferable to use a porous film or a non-woven fabric having excellent rate characteristics singly or in combination. Examples of the material forming the separator for the non-aqueous electrolyte battery include polyolefin resins represented by polyethylene, polypropylene, etc., polyester resins represented by polyethylene terephthalate, polybutylene terephthalate, etc., polyvinylidene fluoride, and vinylidene fluoride-hexa. 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. From the viewpoint of charge / discharge characteristics, the porosity is preferably 20% by volume or more.

The non-aqueous electrolyte battery separator uses a polymer gel composed of an electrolyte and a polymer such as acrylonitrile, ethylene oxide, propylene oxide, methyl methacrylate, vinyl acetate, vinylpyrrolidone or polyvinylidene fluoride. Good.

Furthermore, the non-aqueous electrolyte battery separator is
It is desirable to use a polymer gel in combination with the above-mentioned porous membrane, non-woven fabric or the like, since the liquid retaining property of the electrolytic solution is improved.
That is, by forming a film in which the surface of the polyethylene microporous membrane and the wall surface of the micropores are coated with a lyophilic polymer having a thickness of several μm or less, and holding an electrolytic solution in the micropores of the film, the lyophilic property is obtained. The polymer gels.

Examples of the solvophilic polymer include polyvinylidene fluoride, acrylate monomers having ethylene oxide groups and ester groups, epoxy monomers, and polymers obtained by crosslinking monomers having isocyanate groups. For the cross-linking, an actinic ray such as an ultraviolet ray (UV) or an electron beam (EB) can be used.

For the purpose of controlling strength and physical properties, the above-mentioned solvent-philic polymer may be used by blending with a physical property adjusting agent within a range not interfering with the formation of a crosslinked product. Examples of the physical property adjusting agent include inorganic fillers {metal oxides such as silicon oxide, titanium oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide and iron oxide, metal carbonates such as calcium carbonate and magnesium carbonate}. , Polymers {polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc.} and the like. The addition amount of the physical property adjusting agent is usually 50% by weight or less, preferably 20% by weight or less with respect to the crosslinkable monomer.

Illustrative examples of the acrylate monomer include bifunctional or higher functional unsaturated monomers.
More specific examples include bifunctional (meth) acrylates {ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, adipic acid / dineopentyl glycol ester di (meth) acrylate, 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, polyoxyethylene / polyoxypropylene copolymer di (meth) acrylate, butanediol di (meth) acrylate, hexamethylene glycol di (meth) ) Acrylate etc.} trifunctional (meth)
Acrylate {Trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, tri (meth) acrylate of ethylene oxide adduct of glycerin, tri (meth) acrylate of propylene oxide adduct of glycerin, ethylene oxide of glycerin, propylene oxide addition Object tri (meth) acrylate, etc.}, tetrafunctional or higher polyfunctional (meth) acrylate {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 monomers 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, acrylamido-2-methylpropane sulfonic acid, etc.} or salts thereof (Li salt, Na salt, K salt, ammonium salt,
Tetraalkylammonium salt, etc.), or these unsaturated carboxylic acids are partially esterified with a C1-C18 aliphatic or alicyclic alcohol, alkylene (C2-C4) glycol, polyalkylene (C2-C4) glycol, etc. (Methyl maleate, monohydroxyethyl maleate, etc.) and those partially amidated with ammonia, primary or secondary amine (maleic acid monoamide, N-
Methyl maleic acid monoamide, N, N-diethyl maleic acid monoamide, etc.), (meth) acrylic acid ester [C
Esters of 1-C18 aliphatic (methyl, ethyl, propyl, butyl, 2-ethylhexyl, stearyl, etc.) alcohols with (meth) acrylic acid, or alkylene (C
Ester of (2-C4) glycol (ethylene glycol, propylene glycol, 1,4-butanediol, etc.) and polyalkylene (C2-C4) glycol (polyethylene glycol, polypropylene glycol) with (meth) acrylic acid]; (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 compounds [(meth) acrylonitrile, crotonnitrile, etc.];
Unsaturated alcohol [(meth) allyl alcohol, etc.]; Unsaturated amine [(meth) allylamine, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.]; Heterocycle-containing monomer [N-
Vinylpyrrolidone, vinylpyridine, etc.]; olefinic aliphatic hydrocarbons [ethylene, propylene, butylene, isobutylene, pentene, (C6-C50) α-olefins, etc.]; olefinic alicyclic hydrocarbons [cyclopentene, cyclohexene, cycloheptene, Norbornene, etc.]; olefinic aromatic hydrocarbons [styrene, α-methylstyrene, stilbene, etc.]; unsaturated imides [maleimide, etc.]; halogen-containing monomers [vinyl chloride, vinylidene chloride, vinylidene fluoride, hexafluoropropylene, etc.], etc. Is mentioned.

Examples of the epoxy monomer include glycidyl ethers {bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, brominated bisphenol A diglycidyl ether, phenol novolac glycidyl ether, cresol novolac glycidyl ether, etc.}, glycidyl esters { Hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester, etc.}, glycidyl amines {triglycidyl isocyanurate, tetraglycidyl diaminophenylmethane, etc.}, linear aliphatic epoxides {epoxidized polybutadiene, epoxidized soybean oil, etc.},
Alicyclic epoxides {3,4 epoxy-6 methylcyclohexyl methyl carboxylate, 3,4 epoxy cyclohexyl methyl carboxylate, etc.} and the like can be mentioned. These epoxy resins can be used alone or after curing by adding a curing agent.

Examples of the curing agent include aliphatic polyamines {diethylenetriamine, triethylenetetramine, 3,9- (3-aminopropyl) -2,4,8,1.
0-tetrooxaspiro [5,5] undecane etc.}, aromatic polyamines {metaxylenediamine, diaminophenylmethane etc.}, polyamides {dimer acid polyamide etc.}, acid anhydrides {phthalic anhydride, tetrahydromethyl anhydride Phthalic acid, hexahydrophthalic anhydride, trimellitic anhydride, methylnadic acid anhydride}, phenols {phenol novolac, etc.}, polymercaptans {polysulfide, etc.}, tertiary amines {tris (dimethylaminomethyl) phenol, 2-ethyl -4-methylimidazole, etc., Lewis acid complex {boron trifluoride / ethylamine complex, etc.} and the like.

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

In cross-linking the monomer having an isocyanate group, polyols and polyamines [bifunctional compounds {water, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, etc.] trifunctional compounds {glycerin, trimethylolpropane , 1,2,6-hexanetriol, triethanolamine and the like}, tetrafunctional compounds {pentaerythritol, ethylenediamine, tolylenediamine, diphenylmethanediamine, tetramethylolcyclohexane,
Methyl glucoside etc.}, 5-functional compound {2,2,6,6
-Tetrakis (hydroxymethyl) cyclohexanol, diethylenetriamine, etc., 6-functional compounds {sorbitol, mannitol, dulcitol, etc.}, 8-functional compounds {sucrose, etc.}, and polyether polyols {propylene oxide and / or the polyol or polyamine. Ethylene oxide adduct}, polyester polyol [the above-mentioned polyol and polybasic acid {adipic acid, o, m, p-phthalic acid, succinic acid, azelaic acid,
A compound having active hydrogen such as a condensate with sebacic acid or ricinoleic acid, a polycaprolactone polyol {poly ε-caprolactone etc.}, a polycondensate of hydroxycarboxylic acid etc.] can be used in combination.

A catalyst may be used in combination in the crosslinking reaction. 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 (DABCO), N, N'-dimethylpiperazine, 1,
2-dimethylimidazole, 1,8-diazabicyclo (5,4,0) undecene-7 (DBU), etc., and salts thereof.

The non-aqueous electrolyte battery according to the present invention is, for example,
It is suitably manufactured by pouring an electrolytic solution before or after laminating the separator for a non-aqueous electrolyte battery, the positive electrode and the negative electrode, and finally sealing with an outer package. Further, in a non-aqueous electrolyte battery in which a positive electrode and a negative electrode are wound around a power generation element laminated with a separator for a non-aqueous electrolyte battery, an electrolytic solution is injected into the power generation element before and after the winding. Is preferred. As the injection method, it is possible to inject 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 non-aqueous electrolyte battery, the outer package is preferably a thin material, for example, a metal-resin composite film in which a metal foil is sandwiched between resin films. Specific examples of the metal foil include aluminum,
Iron, nickel, copper, stainless steel, titanium, gold, silver, etc.
The foil is not limited as long as it is a pinhole-free foil, but a lightweight and inexpensive aluminum foil is preferable. As the resin film on the outside of the battery, a resin film having excellent puncture strength such as polyethylene terephthalate film or nylon film can be heat-sealed as the resin film on the inside of the battery such as polyethylene film or nylon film. A film that is present and has solvent resistance is preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0064]

Example (Example 1) A positive electrode was prepared as follows.
LiCoO ₂ as a positive electrode active material, acetylene black as a conductive agent, and polyvinylidene fluoride as a binder were mixed in a weight ratio of 90: 5: 5, and then a positive electrode slurry of the above material was prepared by using N-methylpyrrolidone as a solvent. It was made. N-methylpyrrolidone was removed by applying the positive electrode slurry on both sides of an aluminum foil (thickness 20 μm) as a positive electrode current collector and drying it.
This positive electrode plate was pressed by a roll press to obtain a positive electrode.

The negative electrode was produced as follows. Natural graphite was ground with a jet mill to obtain a negative electrode carbonaceous material. When the X-ray diffraction measurement of the negative electrode carbonaceous material was performed,
Calculation based on the area of the X-ray diffraction pattern using the calculation formula of (Formula 1) revealed that the graphite contained 15% of the rhombohedral crystal system. The negative electrode carbonaceous material, styrene-butadiene rubber as a binder, and carboxymethyl cellulose also as a binder were mixed at 98: 1: 1.
Were mixed in a weight ratio of 1 to prepare a negative electrode slurry of the above material using distilled water. The surface roughness of the negative electrode current collector is 0.3.
The above slurry was applied onto both surfaces of an electrolytic copper foil of μmRa and dried to obtain a negative electrode plate. The negative electrode plate was pressed by a roll press to obtain a negative electrode.

The separator was manufactured as follows.
First, an ethanol solution in which 3% by weight of a bifunctional acrylate monomer having the structure shown in (Chemical Formula 1) was dissolved was prepared, and a polyethylene microporous membrane (average pore diameter 0.1 μm, porosity 50%) as a porous substrate , Thickness 23μm, weight 1
After coating at 2.52 g / m ² and air permeability of 89 seconds / 100 ml), the monomer was cross-linked by electron beam irradiation to form an organic polymer layer, and dried at a temperature of 60 ° C. for 5 minutes. A separator was obtained through the above steps. The obtained separator had a thickness of 24 μm, a weight of 13.04 g / m ² ,
The air permeability was 103 seconds / 100 ml, the weight of the organic polymer layer was about 4% by weight with respect to the weight of the porous material, the thickness of the crosslinked body layer was about 1 μm, and the pores of the porous substrate were almost the same. It was maintained.

[0067]

[Chemical 1]

The positive electrode current collector of the positive electrode and the negative electrode current collector of the negative electrode are provided with an aluminum plate (width 5 m) as a positive electrode terminal.
m, thickness 100 μm) and a nickel plate (width 5 mm, thickness 100 μm) as a negative electrode terminal were respectively connected by electric resistance welding, and the positive electrode and the negative electrode were wound via a separator to obtain a power generating element. . The power-generating element is made up of a cylindrical metal-resin composite film (battery outside resin, metal foil, battery inside resin, polyethylene terephthalate,
It was placed in an outer package made of aluminum foil and modified polypropylene). The non-aqueous electrolyte was obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent in which propylene carbonate, ethylene carbonate and vinylene carbonate were mixed at a volume ratio of 50: 48: 2. The obtained non-aqueous electrolyte was vacuum-injected into the outer package under a reduced pressure of 1333 Pa.
The nonaqueous electrolyte battery of the present invention was produced by vacuum-sealing under a reduced pressure of Pa. This is referred to as Battery 1 of the present invention.
The design capacity of this non-aqueous electrolyte battery is 500 mAh.

(Example 2) By adjusting the conditions such as the time for grinding natural graphite with a jet mill,
Same as Example 1 except that graphite adjusted to include 20% rhombohedral crystal system was used as the negative electrode carbonaceous material from the result calculated using (Equation 1) from the area of the X-ray diffraction pattern. A non-aqueous electrolyte battery was produced by the method described above. This is designated as Battery 2 of the present invention.

(Example 3) By adjusting the conditions such as the time for grinding artificial graphite with a jet mill,
Example 1 was repeated except that graphite adjusted to contain 5% of rhombohedral crystal system was used as the negative electrode carbonaceous material from the result calculated using (Equation 1) from the area of the X-ray diffraction pattern.
A non-aqueous electrolyte battery was produced in the same manner as in. This is designated as Battery 3 of the present invention.

Comparative Example 1 A non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except that artificial graphite containing no rhombohedral system was used as the negative electrode carbonaceous material. This is referred to as Comparative Battery 1.

Comparative Example 2 A non-aqueous electrolyte obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent obtained by mixing propylene carbonate and ethylene carbonate in a volume ratio of 50:50 was used. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except for the above. This is referred to as Comparative Battery 2.

Example 4 A non-aqueous electrolyte obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent in which propylene carbonate, ethylene carbonate and vinylene carbonate were mixed at a volume ratio of 50: 45: 5. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the above was used. This is the battery 4 of the present invention.
And

Example 5 A non-aqueous electrolyte obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent in which propylene carbonate, ethylene carbonate and vinylene carbonate were mixed in a volume ratio of 50: 49: 1. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the above was used. This is the present invention battery 5
And

Example 6 Obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent obtained by mixing propylene carbonate, ethylene carbonate and styrene carbonate in a volume ratio of 50: 49.5: 0.5. A non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except that the non-aqueous electrolyte was used. This is designated as Battery 6 of the present invention.

Example 7 A non-aqueous electrolyte obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent prepared by mixing propylene carbonate, ethylene carbonate and vinylene carbonate in a volume ratio of 60: 38: 2. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the above was used. This is the battery 7 of the present invention.
And

Example 8 By dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent prepared by mixing propylene carbonate, ethylene carbonate, diethyl carbonate and vinylene carbonate in a volume ratio of 40: 48: 10: 2. A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the obtained non-aqueous electrolyte was used. This is designated as Battery 8 of the present invention.

Example 9 A non-aqueous solution obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent prepared by mixing ethylene carbonate, diethyl carbonate and vinylene carbonate in a volume ratio of 48: 50: 2. A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that an electrolyte was used. The present battery 9
And

Comparative Example 3 A non-aqueous electrolyte obtained by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 50:50 was used. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except for the above. This is referred to as Comparative Battery 3.

(Battery Performance Test) The above batteries 1 to 9 of the present invention
Also, the initial efficiency was evaluated at 20 ° C. using Comparative Batteries 1 to 3. Initial charge was 4.2V at 20 ° C, 0.1It (10 hour rate), constant current constant voltage charge for 20 hours, and initial discharge was 20V at final voltage 2.7V, 0.2It (5 hour rate). ) Constant-current discharge. The results are shown in Table 1.

[0081]

[Table 1]

Here, in the battery of the present invention, the initial discharge capacity almost as designed was obtained.
The battery swelled during charging, so I stopped discharging. That is, the battery of the present invention, which uses a carbonaceous material containing a rhombohedral structure and uses a carbonate having an easily reduced carbon-carbon double bond in combination, can suppress decomposition of other non-aqueous solvents. It can be seen that even when the non-aqueous electrolyte containing propylene carbonate was used as the aqueous solvent, the propylene carbonate was not decomposed and gas was not generated, and charging / discharging with high efficiency was possible.
Further, the batteries 1 to 9 of the present invention have 4.2 V at 20 ° C.
1.0 It (1 hour rate), 2 hours of constant current and constant voltage charging, and a final voltage of 2.7 V, 1.0 It (1 hour rate) cycle test was performed, and as a result, all the batteries of the present invention had 300 cycles. After that, 80% or more of the capacity at the beginning of the cycle could be obtained. Therefore, according to the present invention, a battery having good cycle performance can be obtained.

As is clear from the results shown in Table 1, the batteries 1 to 9 of the present invention have a higher discharge capacity than the comparative battery 3 in which the non-aqueous electrolyte does not contain a carbonate having a carbon-carbon double bond. The battery has a high energy density.
This is because the carbonate having a carbon-carbon double bond was used as the non-aqueous electrolyte, so that SEI was formed on the surface of the negative electrode carbonaceous material.
It is considered that this is because the layer was formed, the reductive decomposition of the other non-aqueous solvent used for the non-aqueous electrolyte was prevented, and the irreversible capacity was greatly reduced. In addition, comparing the batteries 1, 2 and 3 of the present invention, it can be seen that the initial discharge capacity of the battery 2 of the present invention is the largest. It is considered that this is because the battery 2 of the present invention contains 20% of the rhombohedral crystal structure. On the contrary, it can be seen that the battery 3 of the present invention has the smallest initial discharge capacity. It is considered that this is because the battery 3 of the present invention contains 5% of the rhombohedral structure. Therefore, the amount of the rhombohedral structure is preferably 5% or more, more preferably 15% or more, and most preferably 20% or more.

Further, in the batteries 4, 5 and 6 of the present invention, the carbonate having a carbon-carbon double bond such as vinylene carbonate or styrene carbonate was used as the non-aqueous electrolyte.
It can be seen that excellent initial characteristics are obtained when the content is 5% or more. Therefore, the amount of carbonate having a carbon-carbon double bond is preferably 0.5% or more.

Further, it is understood that the battery 7 of the present invention has an initial discharge capacity slightly smaller than that of the other batteries of the present invention. It is considered that this is because the battery 7 of the present invention contains 60% by volume of propylene carbonate in the non-aqueous solvent. Therefore, the amount of propylene carbonate in the non-aqueous solvent is preferably less than 60% by volume.

Next, using the present batteries 1 to 9 and the comparative battery 3, the discharge capacity at −20 ° C. was measured. Charging was performed at 4.2 V, 0.2 It (5 hour rate), 7.5 hour constant current and constant voltage charge at 20 ° C., and discharge was −2.
At 0 ° C., the final voltage was 2.7 V, and the constant current discharge was 1.0 It (1 hour rate).

-20 ° C to discharge capacity at 20 ° C
The ratio of the discharge capacity in the above was determined as a "low temperature performance value" in percentage. The results are also shown in Table 1.

Next, using the present batteries 1 to 9 and the comparative battery 3, the swelling of the batteries during high temperature storage was measured. Charging was carried out by constant current constant voltage charging at 4.2 V, 0.2 It (5 hour rate) and 7.5 hours at 20 ° C., and the battery thickness in the final state of charging was measured. 90 ° C for these batteries
Was stored for 4 hours, and the thickness of the battery immediately after storage was measured. The thickness increased by high temperature storage was determined as "high temperature storage performance". The results are also shown in Table 1.

As is clear from these results, the batteries 1 to 8 of the present invention are batteries having excellent low-temperature performance as compared with the comparative battery 3 containing no carbonate having a carbon-carbon double bond in the non-aqueous electrolyte. It was It is considered that this is because the batteries 1 to 8 of the present invention contain propylene carbonate in the non-aqueous electrolyte. That is, the comparative battery 3 in which the non-aqueous electrolyte does not contain propylene carbonate is −
It is considered that at 20 ° C., the non-aqueous solvent of the non-aqueous electrolyte was solidified and could not be discharged. Therefore, the amount of propylene carbonate contained in the non-aqueous electrolyte is preferably 40% by volume or more.

Further, as is clear from these results, the batteries 1 to 8 of the present invention contained 5% diethyl carbonate having a high vapor pressure.
It can be seen that the swelling after storage at high temperature is smaller than that of the comparative battery 3 containing 0%. This means that in the batteries 1 to 8 of the present invention, the non-aqueous electrolyte does not contain a non-aqueous solvent having a vapor pressure at 20 ° C. of higher than 1000 Pa, in particular, the one having a vapor pressure of 500 Pa or less was used, or the content thereof was contained. 10% by volume
It is considered that this is due to the following. Therefore, the amount of the non-aqueous solvent contained in the non-aqueous electrolyte and having a vapor pressure at 20 ° C. of higher than 1000 Pa is preferably 10% by volume or less.

Further, it is understood that the battery 4 of the present invention has a slightly thicker thickness after storage at high temperature than the other batteries of the present invention. This is because in the battery 4 of the present invention, carbon contained in the non-aqueous electrolyte
It is considered that this is because the amount of the carbonate having a carbon double bond is 5% by volume. That is, it is considered that the carbonate having a carbon-carbon double bond, which is inferior in oxidation resistance, decomposed on the positive electrode plate to generate gas. Therefore, the amount of the carbonate having a carbon-carbon double bond in the non-aqueous solvent is preferably less than 5% by volume.

It was also found that the battery of the present invention 6 had a slightly higher impedance after storage at high temperature than the other batteries of the present invention. It is considered that this is because the battery 6 of the present invention contains styrene carbonate as the carbonate having a carbon-carbon double bond contained in the non-aqueous electrolyte. That is, it is considered that styrene carbonate decomposed on the positive electrode plate and increased the impedance of the positive electrode. Therefore, vinylene carbonate is preferred as the carbonate having a carbon-carbon double bond in the non-aqueous solvent.

[0093]

As described above, according to the present invention, as described in claim 1, the negative electrode carbonaceous material contains 5% or more of the rhombohedral crystal structure, and the nonaqueous electrolyte. By containing at least a carbonate having a carbon-carbon double bond, it is possible to ensure ionic conduction without solidification of the non-aqueous electrolyte even at low temperatures,
Further, since it is possible to reliably suppress the decomposition of the non-aqueous solvent other than the carbonate having a carbon-carbon double bond on the negative electrode during charging and sufficiently perform charging, it is possible to obtain good low-temperature performance and high energy density. It is possible to provide a non-aqueous electrolyte battery having both of the following.

Further, according to the present invention, as described in claim 2, by using propylene carbonate having a low vapor pressure and a high boiling point as a main non-aqueous solvent in the non-aqueous electrolyte, a battery after high temperature storage is obtained. Bulge can be suppressed.

Further, according to the present invention, as described in claim 3, since the carbonate having a carbon-carbon double bond contained in the non-aqueous electrolyte is vinylene carbonate, 5 volume of the non-aqueous solvent is obtained. A non-aqueous electrolyte battery with less adverse effects in high temperature storage because it is possible to suppress decomposition of other non-aqueous solvents with a small amount of less than 10%, and because it has a certain degree of oxidation resistance, impedance does not rise easily after high temperature storage. Can be provided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Kozono             2-32 Kosobe-cho, Takatsuki City, Osaka Prefecture Stock             Ceremony company Yuasa Corporation (72) Inventor Toshiyuki Atsuta             2-32 Kosobe-cho, Takatsuki City, Osaka Prefecture Stock             Ceremony company Yuasa Corporation F term (reference) 5H029 AJ02 AJ03 AJ04 AL06 AL07                       AM03 BJ02 BJ14 DJ16 DJ17                       HJ01                 5H050 AA06 AA08 AA10 BA17 CA08                       CA09 CB07 CB08 FA17 FA18                       HA01

Claims (3)

[Claims] 1. A non-aqueous electrolyte battery comprising at least a positive electrode containing a positive electrode active material as a main constituent, a negative electrode containing a negative electrode carbonaceous material as a main constituent, and a non-aqueous electrolyte, wherein the negative electrode carbonaceous material The material contains 5% or more of a rhombohedral structure, and the nonaqueous electrolyte contains at least a carbonate having a carbon-carbon double bond. 2. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte contains propylene carbonate. 3. The carbonate having a carbon-carbon double bond is vinylene carbonate.
The non-aqueous electrolyte battery described.