JP2013033663A - Nonaqueous electrolytic solution, and nonaqueous electrolyte battery comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution improving the cycle characteristics and inhibiting degradation in high-temperature storage characteristics, and a nonaqueous electrolyte battery comprising the nonaqueous electrolytic solution.SOLUTION: A nonaqueous electrolytic solution contains: (A) a phosphazene represented by the formula (1), where Xto Xindependently represent at least one member selected from the group consisting of halogen atoms, alkyl groups, aryl groups, alkoxy groups and aryloxy groups, and may be identical with or different from one another; and (B) a compound having at least one isocyanate group in a molecule. A nonaqueous electrolyte battery comprises the electrolytic solution.

Description

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

With the rapid progress of portable electronic devices such as mobile phones and notebook personal computers, there is an increasing demand for higher capacities for batteries used for the main power source and backup power source, such as nickel cadmium batteries and nickel Non-aqueous electrolyte batteries such as lithium ion secondary batteries having higher energy density than hydrogen batteries have attracted attention.
Examples of the electrolyte solution for the lithium ion secondary battery include LiPF ₆ , LiBF ₄ , LiN (CF ₃ S
O ₂ ) ₂ , LiCF ₃ (CF ₂ ) ₃ SO _{3 and} other electrolytes, mixed solvents of high dielectric constant solvents such as ethylene carbonate and propylene carbonate, and low viscosity solvents such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate A typical example is a non-aqueous electrolyte solution dissolved in the solution.

  In addition, as a negative electrode active material of a lithium ion secondary battery, a carbonaceous material capable of occluding and releasing lithium ions is mainly used, and natural graphite, artificial graphite, amorphous carbon, etc. are listed as representative examples. It is done. Furthermore, metal or alloy negative electrodes using silicon, tin or the like for increasing the capacity are also known. As the positive electrode active material, a transition metal composite oxide capable of mainly inserting and extracting lithium ions is used, and representative examples of the transition metal include cobalt, nickel, manganese, iron and the like.

In such lithium ion secondary batteries, various studies have been made on non-aqueous solvents and electrolytes in order to improve battery characteristics.
Patent Document 1 discloses that battery safety can be improved by using phosphazene as a solvent.
Patent Document 2 discloses that thermal stability and cycle characteristics are improved by including a cyclic carbonate having a carbon-carbon unsaturated double bond together with phosphazenes.

In addition, since lithium ion secondary batteries use a highly active positive electrode and negative electrode, it is known that the charge / discharge capacity decreases due to side reactions between the electrode and the electrolyte, in order to improve battery characteristics. In addition, various studies have been made on non-aqueous solvents and electrolytes.
Patent Document 3 discloses that by adding a compound having an isocyanate group to a non-aqueous electrolyte, the decomposition reaction of the solvent on the negative electrode is suppressed, and the cycle characteristics of the battery are improved.

  Patent Document 4 discloses that by adding a compound having an isocyanate group and an unsaturated cyclic carbonate to a non-aqueous electrolyte, a film is formed stepwise on the negative electrode, and the cycle characteristics of the battery are improved. ing.

JP 2002-83628 A JP 2006-24380 A JP 2005-259641 A JP 2006-164759 A

In recent years, the demand for higher performance of lithium secondary batteries has been increasing, and various characteristics such as high capacity, cycle characteristics, high temperature storage characteristics, continuous charge characteristics, overcharge characteristics, battery safety, etc. It is required to achieve together.
When the technology described in Patent Document 1 is applied to improve safety, the negative electrode film of the battery becomes unstable and the side reaction proceeds when charging and discharging are repeated. Therefore, deterioration due to the side reaction at the negative electrode becomes a problem. The characteristics, high-temperature storage characteristics, cycle characteristics, etc. have not yet been satisfactory.
In addition, when the electrolytic solution described in Patent Document 2 is used, deterioration due to side reactions at the negative electrode of phosphazenes can be suppressed, but all battery characteristics such as initial characteristics, high temperature storage characteristics, and cycle characteristics are still unsatisfactory. It wasn't good.

Moreover, when using the electrolyte solution using the additive described in Patent Documents 3 and 4, although the side reaction at the negative electrode is suppressed, the deterioration of the battery characteristics due to the side reaction at the positive electrode was a problem. The battery characteristics were not yet satisfactory.
The present invention has been made in view of the above problems, and an object thereof is to provide a lithium secondary battery in which various characteristics of the battery, in particular, high temperature storage characteristics and cycle characteristics are remarkably improved while maintaining initial characteristics. To do.

As a result of intensive studies to solve the above-mentioned problems, the present inventors use a non-aqueous electrolytic solution characterized by containing a phosphazene having a specific structure and a compound having a plurality of isocyanate groups. Thus, the inventors have found that the cycle characteristics and the high-temperature storage characteristics are remarkably improved while maintaining various characteristics, in particular, the initial characteristics of the electrolyte, and the present invention has been completed.
That is, the gist of the present invention is as follows.
(A) a non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte is at least (A) phosphazenes represented by the following general formula (1), and
(B) A non-aqueous electrolyte containing a compound having at least one isocyanate group in the molecule.

(In the general formula (1), X ^{1 to} X ⁶ each independently represent at least one selected from the group of a halogen atom, an alkyl group, an aryl group, an alkoxy group or an aryloxy group, and are the same. May be different.)
(B) The non-aqueous electrolyte solution according to (a), wherein the phosphazene represented by the general formula (1) is contained in an amount of 0.01 to 50% by mass in the non-aqueous electrolyte solution.
(C) The non-aqueous electrolyte solution according to (a), wherein the phosphazene represented by the general formula (1) is contained in an amount of 3 to 50% by mass in the non-aqueous electrolyte solution.
(D) The non-aqueous electrolyte solution according to (a), wherein the phosphazenes represented by the general formula (1) are contained in an amount of 0.01 to 5% by mass in the non-aqueous electrolyte solution.
(E) In the general formula (1), at least one of X ^{1 to} X ⁶ is a halogen atom, and at least one of X ^{1 to} X ⁶ is an alkoxy group or an aryloxy group. The nonaqueous electrolytic solution according to any one of (a) to (d).
(F) The non-aqueous electrolysis according to any one of (a) to (e), wherein the compound having at least one isocyanate group in the molecule is represented by the following general formula (2): liquid.

(X ⁷ ) − (N═C═O) _n (2)
(In the general formula (2), X ⁷ represents an organic group composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, and , N represents an integer of 1 to 5.
(G) In any one of (a) to (f), in the general formula (2), X ⁷ represents an organic group having 2 to 14 carbon atoms, and n is 2 or more. Non-aqueous electrolyte battery.
(H) The non-aqueous electrolyte solution according to any one of (a) to (g), wherein the non-aqueous electrolyte solution contains the compound (B) in an amount of 0.01 to 10% by mass. .
(I) In the non-aqueous electrolyte, at least one selected from the group consisting of a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, and a difluorophosphate The non-aqueous electrolyte solution according to any one of (a) to (h), comprising:
(J) The cyclic carbonate having a fluorine atom is at least one compound selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate, The non-aqueous electrolyte according to (i), wherein the cyclic carbonate having a saturated bond is at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate.
(K) A non-aqueous electrolyte battery including a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is a non-aqueous electrolyte according to any one of (a) to (i) A non-aqueous electrolyte battery characterized by being an aqueous electrolyte.

One feature of the present invention is that a phosphazene having a specific structure and a compound having an isocyanate group are used in a non-aqueous electrolyte battery.
The inventors of the present invention include a specific phosphazene and a compound having an isocyanate group in the molecule in a non-aqueous electrolyte solution, whereby the phosphazene and the compound having an isocyanate group form a composite film on the negative electrode. Therefore, it was found that side reactions on the negative electrode were suppressed, and that side reactions of the compounds having isocyanate groups were suppressed because phosphazenes reacted on the positive electrode to show the positive electrode protection effect. As a result, the initial performance of the battery was maintained. However, it has been found that the effect of improving high-temperature storage characteristics and cycle characteristics is remarkably improved.

  That is, according to the present invention, it is possible to provide a non-aqueous electrolyte battery excellent in initial battery characteristics, high-temperature storage, and cycle characteristics.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
1. Non-aqueous electrolyte The non-aqueous electrolyte of the present invention relates to a non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent.

1-1. Phosphazenes represented by general formula (1) The non-aqueous electrolyte solution of the present invention contains phosphazenes represented by the following general formula (1) and a compound having at least one isocyanate group in the molecule. Features.

(In the general formula (1), X ^{1 to} X ⁶ each independently represent at least one selected from the group of a halogen atom, an alkyl group, an aryl group, an alkoxy group or an aryloxy group, and are the same. May be different.)
Among these, a halogen atom, an alkoxy group, or an aryloxy group is preferable from the viewpoint of electrochemical stability. As the halogen atom, fluorine, chlorine and bromine are more preferable, and fluorine is most preferable from the viewpoint of electrochemical stability and flame retardancy. On the other hand, the number of carbon atoms of the alkyl group and aryl group is not particularly limited. However, the alkoxy group preferably has a carbon number of 10 or less, more preferably because the flame retardancy is reduced as the number of carbon atoms increases. Preferably has 6 or less carbon atoms, and more preferably only 3 or less carbon atoms with respect to the alkoxy group alone.

The above Xs may all be the same type of substituents as long as they satisfy the basic performance as an electrolyte such as viscosity, conductivity, electrochemical stability, and safety, but two or more different types You may combine a substituent.
Specific examples of these alkoxy groups include methoxy group, fluoromethoxy group, difluoromethoxy group, trifluoromethoxy group, ethoxy group, 1-fluoroethoxy group, 2-fluoroethoxy group, 1,1-difluoroethoxy group, 1, 2-difluoroethoxy group, 2,2-difluoroethoxy group, 1,1,2-trifluoroethoxy group, 1,2,2-trifluoroethoxy group, 2,2,2-trifluoroethoxy group, 1,1 , 2,2-tetrafluoroethoxy group, 1,2,2,2-tetrafluoroethoxy group, pentafluoroethoxy group, propoxy group (n-propoxy group), 1-fluoropropoxy group, 2-fluoropropoxy group, 3 -Fluoropropoxy group, 1,1-difluoropropoxy group, 1,2-difluoropropoxy group, 1,3- Fluoropropoxy group, 2,2-difluoropropoxy group, 2,3-difluoropropoxy group, 3,3-difluoropropoxy group, 1,1,2-trifluoropropoxy group, 1,2,2-trifluoropropoxy group, 1,1,3-trifluoropropoxy group, 1,2,3-trifluoropropoxy group, 1,3,3-trifluoropropoxy group, 2,2,3-trifluoropropoxy group, 2,3,3- Trifluoropropoxy group, 3,3,3-trifluoropropoxy group, 1,1,2,2-tetrafluoropropoxy group, 1,1,2,3-tetrafluoropropoxy group, 1,1,3,3- Tetrafluoropropoxy group, 1,2,2,3-tetrafluoropropoxy group, 1,2,3,3-tetrafluoropropoxy group, 2,2,3,3-tetra Fluoropropoxy group, 2,3,3,3-tetrafluoropropoxy group, 1,1,2,2,3-pentafluoropropoxy group, 1,2,2,3,3-pentafluoropropoxy group, 1, 1,3,3,3-pentafluoropropoxy group, 1,2,3,3,3-pentafluoropropoxy group, 2,2,3,3,3-pentafluoropropoxy group, 1,1,2,2 , 3,3-hexafluoropropoxy group, 1,1,2,3,3,3-hexafluoropropoxy group, 1,2,2,3
3,3-hexafluoropropoxy group, heptafluoropropoxy group, 1-methylethoxy group (i-propoxy group), 1-fluoro-1-methylethoxy group, 2-fluoro-1-methylethoxy group, 1,2- Difluoro-1-methylethoxy group, 1,2-difluoro-1- (fluoromethyl) ethoxy group, 1,2,2-trifluoro-1-methylethoxy group, 2,2,2-trifluoro-1-methyl Ethoxy group, 2,2, -difluoro-1- (fluoromethyl) ethoxy group, 1,2,2,2-tetrafluoro-1-methylethoxy group, 1,2,2-trifluoro-1- (fluoromethyl) ) Ethoxy group, 2,2,2-trifluoro-1- (fluoromethyl) ethoxy group, 2,2-difluoro-1- (difluoromethyl) ethoxy group, 1,2,2 2-tetrafluoro-1- (fluoromethyl) ethoxy group, 1,2,2-trifluoro-1- (difluoromethyl) ethoxy group, 2,2,2-trifluoro-1- (difluoromethyl) ethoxy group, 1,2,2,2-tetrafluoro-1- (difluoromethyl) ethoxy group, 2,2,2-trifluoro-1- (trifluoromethyl) ethoxy group, 1,2,2,2-tetrafluoro- 1- (trifluoromethyl) ethoxy group and the like can be mentioned.

  As specific examples of the aryloxy group, an unsubstituted or fluorine-substituted phenoxy group is preferable. Specifically, a phenoxy group, a 2-fluorophenoxy group, a 3-fluorophenoxy group, a 4-fluorophenoxy group, 2, 3 -Difluorophenoxy group, 2,4-difluorophenoxy group, 2,5-difluorophenoxy group, 2,6-difluorophenoxy group, 3,4-difluorophenoxy group, 3,5-difluorophenoxy group, 2,3,4 -Trifluorophenoxy group, 2,3,5-trifluorophenoxy group, 2,3,6-trifluorophenoxy group, 2,4,5-trifluorophenoxy group, 2,4,6-trifluorophenoxy group, 3,4,5-trifluorophenoxy group, 2,3,4,5-tetrafluorophenoxy group, 2,3,4, - tetra-fluorophenoxy group, 2,3,5,6-fluorophenoxy group, pentafluorophenoxy group, and the like.

Among these, methoxy group, trifluoromethoxy group, ethoxy group, 2,2,2-trifluoroethoxy group, propoxy group, 1-methylethoxy group (i-
Propoxy group) and phenoxy group are more preferable, and methoxy group, ethoxy group and phenoxy group are particularly preferable.
As the compound represented by the general formula (1), specifically,

Among these, preferably from the viewpoint of boiling point, etc.

Etc. Furthermore, from the viewpoint that there are few side reactions in the battery and it is difficult to inhibit the battery reaction,

Is mentioned.
Phosphazenes may be used alone or in combination of two or more in any combination and ratio.
There is no limit to the amount of phosphazenes added to the entire non-aqueous electrolyte solution of the present invention, and it is optional as long as the effects of the present invention are not significantly impaired. When used as a non-aqueous solvent, Usually 0.01% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, most preferably 12% by mass or more, and preferably 50% by mass or less, More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less, Most preferably, it is 20 mass% or less. Within this range, the non-aqueous electrolyte secondary battery can prevent further deterioration of the load characteristics of the battery without inhibiting the dissolution of the Li salt, and can further impart flame retardancy, improving cycle characteristics. The effects of the invention such as these can be fully exhibited.

In addition, since phosphazenes act on the positive electrode during the charge / discharge reaction of the battery, they exhibit an effective function not only as a non-aqueous solvent but also as an auxiliary agent. When phosphazenes are used as an auxiliary agent, the blending amount is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.5% by mass in 100% by mass of the non-aqueous electrolyte solution. As mentioned above, it is 1.0 mass% or more most preferably, Preferably it is 5 mass% or less, More preferably, it is 4 mass% or less, More preferably, it is 3 mass% or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exerted.

1-2. Compound having at least one isocyanate group in the molecule The non-aqueous electrolyte solution of the present invention comprises a compound having at least one isocyanate group in the molecule in addition to the phosphazenes represented by the general formula (1). It is characterized by containing.
The molecular weight of the compound having at least one isocyanate group in the molecule is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 80 or more, more preferably 115 or more, still more preferably 160 or more, and is 400 or less, more preferably 270 or less, and even more preferably 200 or less. If it is this range, it will be easy to ensure the solubility of the isocyanate compound with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The method for producing the isocyanate compound is not particularly limited, and any known method can be selected and produced.

  The compound having at least one isocyanate group in the molecule includes an alkylene derivative having an isocyanate group, or alkenylene derivative, cycloalkylene derivative, alkynylene derivative, cycloalkenylene derivative, arylene derivative, carbonyl derivative, sulfonyl derivative, sulfinyl derivative, phosphonyl. Examples thereof include derivatives, phosphinyl derivatives, amide derivatives, imide derivatives, ether derivatives, thioether derivatives, borinic acid derivatives, borane derivatives, and compounds having metal ions.

Among these, a compound having an alkylene group, an alkenylene group, a cycloalkylene group, an alkynylene group, or an arylene group is preferable from the viewpoint of improving battery characteristics.
Specific examples of the compound having at least one isocyanate group in the molecule include the following compounds.
Methyl isocyanate,
Ethyl isocyanate,
Propyl isocyanate,
Isopropyl isocyanate,
Butyl isocyanate,
Tertiary butyl isocyanate,
Pentyl isocyanate hexyl isocyanate,
Cyclohexyl isocyanate,
Vinyl isocyanate,
Allyl isocyanate,
Ethynyl isocyanate,
Propynyl isocyanate,
Phenyl isocyanate,
Fluorophenyl isocyanate,
3- (triethoxysilyl) propyl isocyanate,
2-isocyanatoethyl acrylate,
A compound having one isocyanate group, such as 2-isocyanatoethyl methacrylate,
Monomethylene diisocyanate,
Dimethylene diisocyanate,
Trimethylene diisocyanate,
Tetramethylene diisocyanate,
Pentamethylene diisocyanate,
Hexamethylene diisocyanate,
Heptamethylene diisocyanate,
Octamethylene diisocyanate,
Nonamethylene diisocyanate,
Decamethylene diisocyanate,
1,3-diisocyanatepropane,
1,4-diisocyanate 2-butene,
1,4-diisocyanate 2-fluorobutane,
1,4-diisocyanate 2,3-difluorobutane,
1,5-diisocyanate 2-pentene,
1,5-diisocyanate 2-methylpentane,
1,6-diisocyanate 2-hexene,
1,6-diisocyanate 3-hexene,
1,6-diisocyanate 3-fluorohexane,
1,6-diisocyanate 3,4-difluorohexane,
Toluene diisocyanate,
Xylene diisocyanate,
Tolylene diisocyanate,
1,2-bis (isocyanatomethyl) cyclohexane,
1,3-bis (isocyanatomethyl) cyclohexane,
1,4-bis (isocyanatomethyl) cyclohexane,
1,2-diisocyanate cyclohexane,
1,3-diisocyanate cyclohexane,
1,4-diisocyanate cyclohexane,
Dicyclohexylmethane-1,1′-diisocyanate,
Dicyclohexylmethane-2,2′-diisocyanate,
Dicyclohexylmethane-3,3′-diisocyanate,
Dicyclohexylmethane-4,4′-diisocyanate,
Compounds having two isocyanate groups, such as isophorone diisocyanate,
Monomethylene triisocyanate,
Dimethylene triisocyanate,
Trimethylene triisocyanate,
Tetramethylene triisocyanate,
Pentamethylene triisocyanate,
Hexamethylene triisocyanate,
Heptamethylene triisocyanate,
Octamethylene triisocyanate,
Nonamethylene triisocyanate,
Decamethylene triisocyanate,
Tol entry isocyanate,
Xylene triisocyanate,
A compound having three isocyanate groups such as tolylene triisocyanate,
Monomethylene tetraisocyanate,
Dimethylene tetraisocyanate,
Trimethylene tetraisocyanate,
Tetramethylenetetraisocyanate,
Pentamethylene tetraisocyanate,
Hexamethylene tetraisocyanate,
Heptamethylene tetraisocyanate,
Octamethylene tetraisocyanate,
Nonamethylene ditetraisocyanate,
Decamethylene tetraisocyanate,
Toluene tetraisocyanate,
Xylene tetraisocyanate,
Compounds having four isocyanate groups such as tolylenetetraisocyanate,
Monomethylene pentaisocyanate,
Dimethylene pentaisocyanate,
Trimethylene pentaisocyanate,
Pentamethylene pentaisocyanate,
Pentamethylene pentaisocyanate,
Hexamethylene pentaisocyanate,
Heptamethylene pentaisocyanate,
Octamethylene pentaisocyanate,
Nonamethylene dipentaisocyanate,
Decamethylene pentaisocyanate,
Toluene pentaisocyanate,
Xylene pentaisocyanate,
Examples include compounds having five isocyanate groups such as tolylene pentaisocyanate.

Among these, a compound having two or more isocyanate groups is preferable from the viewpoint of improving storage characteristics because it forms a good negative electrode film having a crosslinked structure.
In addition, a compound having 2 to 3 isocyanate groups is more preferable because it forms a good negative electrode film having a cross-linked structure, further reduces side reactions with the positive electrode, and as a result further improves battery characteristics.

  Monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, monomethylene triisocyanate, dimethylene triisocyanate Isocyanate compounds such as isocyanate, trimethylene triisocyanate, tetramethylene triisocyanate, pentamethylene triisocyanate, hexamethylene triisocyanate, heptamethylene triisocyanate, octamethylene triisocyanate, nonamethylene triisocyanate, decamethylene triisocyanate , Hardly decomposes during the charge and discharge reaction of the battery becomes more dense the coating formed on the negative electrode from the symmetry of the molecule, as a result, to further improve the battery characteristics, further preferred.

In addition, diisocyanate compounds such as hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate form a denser film on the negative electrode, and as a result, battery characteristics are further improved. Most preferable because of improvement.
A compound having at least one isocyanate group in the molecule may be used alone or in combination of two or more in any combination and ratio. There is no restriction | limiting in the compounding quantity of the isocyanate compound with respect to the whole nonaqueous electrolyte solution of this invention, Although it is arbitrary unless the effect of this invention is impaired remarkably, Usually 0.001 mass% with respect to the nonaqueous electrolyte solution of this invention. The content is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

1-3. A cyclic carbonate having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate and a difluorophosphate The nonaqueous electrolytic solution according to the present invention further includes a cyclic having a carbon-carbon unsaturated bond. It is preferable to contain at least one compound selected from the group consisting of a carbonate compound, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate, and a difluorophosphate. When the above compound is contained, battery characteristics are further improved.

At least one compound selected from the group consisting of a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate and a difluorophosphate is a protective film that is stable on the surface of the negative electrode Can be formed, the side reaction between the negative electrode and the electrolyte component can be suppressed, and high-temperature storage characteristics and cycle characteristics can be improved.
Further, when a cyclic carbonate compound having a carbon-carbon unsaturated bond and a cyclic carbonate compound having a fluorine atom are contained, the gas generation amount tends to increase during high-temperature storage, but it is represented by the general formula (1). Use in combination with phosphazenes and a compound group formed by mixing a compound having at least one isocyanate group in the molecule is preferable because capacity deterioration and gas generation during storage at high temperatures can be suppressed. In particular, the effect is remarkable when used in combination with a cyclic carbonate having a carbon-carbon unsaturated bond or a cyclic carbonate compound having a fluorine atom.

<Cyclic carbonate having a carbon-carbon unsaturated bond>
As the cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter sometimes abbreviated as “unsaturated cyclic carbonate”), any cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond may be used. There is no limitation, and any unsaturated carbonate can be used. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate. Examples of unsaturated cyclic carbonates include vinylene carbonates, aromatic carbonates, ethylene carbonates substituted with a substituent having a carbon-carbon double bond or carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, Catechol carbonates etc. are mentioned.

As vinylene carbonates, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4 , 5-diallyl vinylene carbonate and the like.

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

Among them, particularly preferred unsaturated cyclic carbonates for use in combination with phosphazenes represented by the general formula (1) and a compound group in which a compound having at least one isocyanate group in the molecule is mixed include vinylene carbonate, Methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-
Vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynyl Ethylene carbonate is mentioned. Vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are particularly preferable because they form a more stable interface protective film.

  The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 86 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily. The molecular weight of the unsaturated cyclic carbonate is more preferably 86 or more and 150 or less. The production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.

  An unsaturated cyclic carbonate may be used individually by 1 type, or may have 2 or more types by arbitrary combinations and ratios. Moreover, the compounding quantity of unsaturated cyclic carbonate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The blending amount of the unsaturated cyclic carbonate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and further preferably 0.1% by mass or more, in 100% by mass of the non-aqueous electrolyte solution. Moreover, Preferably it is 5 mass% or less, More preferably, it is 4 mass% or less, More preferably, it is 3 mass% or less. Within this range, the non-aqueous electrolyte battery tends to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics deteriorate, the amount of gas generated increases, and the discharge capacity maintenance ratio decreases. Easy to avoid.

<Cyclic carbonate having a fluorine atom>
The cyclic carbonate having a fluorine atom (hereinafter sometimes abbreviated as “fluorinated cyclic carbonate”) is not particularly limited as long as it is a cyclic carbonate having a fluorine atom.
Examples of the fluorinated cyclic carbonate include derivatives of cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, such as ethylene carbonate derivatives. Examples of the ethylene carbonate derivative include fluorinated products of ethylene carbonate or ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms), and particularly those having 1 to 8 fluorine atoms. Is preferred.

  Specifically, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4- Fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethyl Le ethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

Among them, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate gives high ion conductivity and suitably forms an interface protective film. And more preferable. A fluorinated cyclic carbonate may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.

  When fluorinated cyclic carbonate is used as the non-aqueous solvent, the blending amount is 3% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass in 100% by mass of the non-aqueous solvent. Further, it is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, avoiding a decrease in discharge capacity maintenance rate due to a decrease in high-temperature storage characteristics and an increase in gas generation amount. It's easy to do.

  Moreover, the cyclic carbonate which has a fluorine atom expresses an effective function not only as a non-aqueous solvent but also as an auxiliary agent. The blending amount when using fluorinated cyclic carbonate as an auxiliary agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably 0.5% in 100% by mass of the non-aqueous electrolyte solution. It is at least 5% by mass, preferably at most 5% by mass, more preferably at most 4% by mass, even more preferably at most 3% by mass. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exerted.

<Monofluorophosphate and difluorophosphate>
The counter cation of monofluorophosphate and difluorophosphate is not particularly limited, but lithium, sodium, potassium, magnesium, calcium, and NR ¹ R ² R ³ R ⁴ (wherein R ^{1 to} R ⁴ Are each independently a hydrogen atom or an organic group having 1 to 12 carbon atoms.)

Although it does not specifically limit as a C1-C12 organic group represented by R < ¹ > -R < ⁴ > of the said ammonium, For example, it is substituted by the alkyl group, halogen atom, or alkyl group which may be substituted by the halogen atom. Examples thereof include an cycloalkyl group which may be substituted, an aryl group which may be substituted with a halogen atom or an alkyl group, and a nitrogen atom-containing heterocyclic group which may have a substituent. Among these, as R ^{1 to} R ⁴ , a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group is preferable.

  Specific examples of monofluorophosphate and difluorophosphate include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. And lithium monofluorophosphate and lithium difluorophosphate are preferable, and lithium difluorophosphate is more preferable.

Monofluorophosphate and difluorophosphate may be used alone or in combination of two or more in any combination and ratio. Moreover, the compounding quantity of a monofluoro phosphate and a difluoro phosphate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The blending amount of monofluorophosphate and difluorophosphate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% in 100% by mass of the non-aqueous electrolyte. It is at least 5% by mass, preferably at most 5% by mass, more preferably at most 4% by mass, even more preferably at most 3% by mass. Within this range, the non-aqueous electrolyte battery tends to exhibit a sufficient cycle characteristics improvement effect, and the high temperature storage characteristics deteriorate, the amount of gas generated increases, and the discharge capacity maintenance ratio decreases. Easy to avoid.

1-4. Electrolyte <Lithium salt>
As the electrolyte, a lithium salt is usually used. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any lithium salt can be used. Specific examples include the following.

For _{example, LiPF 6, LiBF 4, LiClO} 4, LiAlF 4, LiSbF 6, LiTa
Inorganic lithium salts such as F ₆ and LiWF ₇ ; lithium tungstates such as LiWOF ₅ ; HC
O ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li, CF ₃ CO ₂ Li, C
_{F 3 CH 2 CO 2 Li,} CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CF 2 CO 2 carboxylic acid lithium salts such as Li; FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ F
Lithium sulfonate such as SO ₃ Li, CHF ₂ SO ₃ Li, CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ Li, etc. Salts; LiN (F
CO) ₂ , LiN (FCO) (FSO ₂ ), LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (C
_{F 3 SO 2), LiN (} CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, lithium cyclic 1,2
Lithium imide salts such as perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); L
Lithium methides such as iC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ ; lithium difluorooxalatoborate, lithium bis (oxalato) borate, lithium bis (malonato) borate Lithium oxalate borate salts such as lithium difluoro (malonato) borate; lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate, lithium tris (malonato) phosphate, lithium difluoro Lithium oxalatophosphate salts such as bis (malonato) phosphate and lithium tetrafluoro (malonato) phosphate; other, LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂
F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , L
iBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , Li
And fluorine-containing organic lithium salts such as BF ₂ (CF ₃ SO ₂ ) ₂ and LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ .

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalate phosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF _{3 C 2 F 5, LiPF 3 (} CF 3) 3, LiPF 3 (C 2 F 5) 3 or the like is output characteristics and high Over preparative charge and discharge characteristics, high-temperature storage characteristics, particularly preferred from the viewpoint that an effect of improving the cycle characteristics and the like.

These lithium salts may be used alone or in combination of two or more. A preferred example in the case of using two or more types in combination is a combination of LiPF ₆ and LiBF ₄ , LiPF ₆ and FSO ₃ Li, etc., and has an effect of improving load characteristics and cycle characteristics. In this case, the concentration of LiBF ₄ or FSO ₃ Li with respect to 100% by mass of the entire non-aqueous electrolyte solution is not limited as long as the amount of the present invention is not significantly impaired. On the other hand, it is usually 0.01% by mass or more, preferably 0.1% by mass or more, while its upper limit is usually 30% by mass or less, preferably 20% by mass or less.

Another example is the combined use of an inorganic lithium salt and an organic lithium salt, and the combined use of both has the effect of suppressing deterioration due to high-temperature storage. Examples of the organic lithium salt include CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) _2. , Lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalate phosphate, lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF ₃
C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (C ₂ F ₅ ) _{3 and the} like are preferable. In this case, the ratio of the organic lithium salt to 100% by mass of the whole non-aqueous electrolyte is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, preferably 30% by mass or less, particularly preferably. It is 20 mass% or less.

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

1-5. Nonaqueous solvent There is no restriction | limiting in particular about the nonaqueous solvent in this invention, It is possible to use a well-known organic solvent. Examples thereof include cyclic carbonates having no fluorine atom, chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, sulfone compounds, and the like.

<Cyclic carbonate not having fluorine atoms>
Examples of the cyclic carbonate having no fluorine atom include those having an alkylene group having 2 to 4 carbon atoms.
Specific examples of the cyclic carbonate having no fluorine atom having 2 to 4 carbon atoms include alkylene carbonates having an alkylene group having 2 to 4 carbon atoms such as ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

The cyclic carbonate which does not have a fluorine atom may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.
The blending amount of the cyclic carbonate not having a fluorine atom is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. However, the lower limit of the blending amount when using one kind alone is a non-aqueous solvent. In 100 mass%, it is 5 mass% or more, More preferably, it is 10 mass% or more. By setting this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the non-aqueous electrolyte is avoided, and the high current discharge characteristics, stability against the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery are in a good range. And it will be easier. Moreover, an upper limit is 95 mass% or less, More preferably, it is 90 mass% or less, More preferably, it is 85 mass% or less. By setting it as this range, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, the decrease in ionic conductivity is suppressed, and the load characteristics of the non-aqueous electrolyte battery are easily set in a favorable range.

<Chain carbonate>
As a chain carbonate, a C3-C7 thing is preferable.
Specifically, as the chain carbonate having 3 to 7 carbon atoms, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, Examples include n-butyl methyl carbonate, isobutyl methyl carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, t-butyl ethyl carbonate.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl n-propyl carbonate are preferable, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferable. is there.
Further, a chain carbonate having a fluorine atom (hereinafter sometimes abbreviated as “fluorinated chain carbonate”) can also be suitably used. The number of fluorine atoms contained in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or may be bonded to different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

Examples of the fluorinated dimethyl carbonate derivative include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate, and the like.
Fluorinated ethyl methyl carbonate derivatives include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2-trimethyl Examples include fluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, and ethyl trifluoromethyl carbonate.

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

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

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

  The compounding amount of the cyclic carboxylic acid ester is usually 5% by volume or more, more preferably 10% by weight or more, in 100% by weight of the non-aqueous solvent. If it is this range, it will become easy to improve the electrical conductivity of a non-aqueous electrolyte solution, and to improve the large current discharge characteristic of a non-aqueous electrolyte battery. Moreover, the compounding quantity of cyclic carboxylic acid ester becomes like this. Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

<Chain carboxylic acid ester>
Examples of the chain carboxylic acid ester include those having 3 to 7 carbon atoms in the structural formula.
Specifically, methyl acetate, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-t-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, Isopropyl propionate, n-butyl propionate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, isobutyric acid-n- Examples include propyl and isopropyl isobutyrate.

Among them, methyl acetate, ethyl acetate, acetate-n-propyl, acetate-n-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, isopropyl propionate, methyl butyrate, ethyl butyrate, etc. It is preferable from the viewpoint of improvement of ionic conductivity.
The amount of the chain carboxylic acid ester is usually 10% by mass or more, more preferably 15% by mass or more, in 100% by mass of the non-aqueous solvent. By setting the lower limit in this way, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the large current discharge characteristics of the non-aqueous electrolyte battery are easily improved. Moreover, the compounding quantity of chain | strand-shaped carboxylic acid ester is in a nonaqueous solvent 100 mass%, Preferably it is 60 mass% or less, More preferably, it is 50 mass% or less. By setting the upper limit in this way, an increase in negative electrode resistance is suppressed, and the large current discharge characteristics and cycle characteristics of the non-aqueous electrolyte battery are easily set in a favorable range.

<Ether compound>
As the ether compound, a chain ether having 3 to 10 carbon atoms in which part of hydrogen may be substituted with fluorine, and a cyclic ether having 3 to 6 carbon atoms are preferable.
Examples of the chain ether having 3 to 10 carbon atoms include diethyl ether, di (2-fluoroethyl) ether, di (2,2-difluoroethyl) ether, di (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2 -Trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (2,2,2-trifluoroethyl) (1,1,2,2-tetrafluoro) Ethyl) ether, ethyl-n-propyl ether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) Ether, ethyl (2,2,3,3-tetrafluoro -n
-Propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl ether, (2-fluoroethyl) (3-fluoro-n-propyl) ) Ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, 2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propyl ether, (2,2,2-trifluoroethyl) ) (3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,2-trifluoro) Oloethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,2-trifluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl) (3-fluoro-n-propyl) ether, (1,1,2,2 -Tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) Ether, (1,1,2,2-tetrafluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propyl ether, (n-propyl) (3- Fluoro-n-pro ) Ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (n -Propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (3-fluoro-n-propyl) ether, (3-fluoro-n-propyl) (3,3,3 -Trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2 , 3,3,3-pentafluoro-n-propyl) ether, di (3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl) (2, 2,3,3-tetrafluoro -N-propyl) ether, (3,3,3-trifluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (2,2,3,3) -Tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, di (2, 2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy (2-fluoroethoxy) methane, methoxy (2,2,2-trifluoroethoxy) ) Methanemethoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy (2,2,2-trifluoro) Roethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, di (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) methane, (2 -Fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) methanedi (2,2,2-trifluoroethoxy) methane, (2,2,2-trifluoroethoxy) (1,1,2,2 -Tetrafluoroethoxy) methane, di (1,1,2,2-tetrafluoroethoxy) methane, dimethoxyethane, methoxyethoxyethane, methoxy (2-fluoroethoxy) ethane, methoxy (2,2,2-trifluoroethoxy) ) Ethane, methoxy (1,1,2,2-tetrafluoroethoxy) ethane, diethoxyethane, ethoxy (2-fur Roethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, di (2-fluoroethoxy) ethane, (2-fluoroethoxy) ( 2,2,2-trifluoroethoxy) ethane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (2,2,2-trifluoroethoxy) ethane, (2, 2,2-trifluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, di (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol Examples thereof include di-n-butyl ether and diethylene glycol dimethyl ether.

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

  The compounding amount of the ether-based compound is usually 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and preferably 70% by mass or less, in 100% by mass of the nonaqueous solvent. More preferably, it is 60 mass% or less, More preferably, it is 50 mass% or less. If it is this range, it is easy to ensure the improvement effect of the lithium ion dissociation degree of chain ether, and the improvement of the ionic conductivity derived from a viscosity fall, and when a negative electrode active material is a carbonaceous material, a chain ether with lithium ion It is easy to avoid a situation where the capacity is reduced due to co-insertion.

<Sulfone compounds>
As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.
Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones that are monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones that are disulfone compounds. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.

The sulfolane is preferably sulfolane and / or a sulfolane derivative (hereinafter sometimes abbreviated as “sulfolane” including sulfolane). As the sulfolane derivative, one in which one or more hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable.
Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methyl sulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ionic conductivity and high input / output.

As the chain sulfone, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n- Butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, Trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trif Oromethylsulfone, perfluoroethylmethylsulfone, ethyltrifluoroethylsulfone, ethylpentafluoroethylsulfone, di (trifluoroethyl) sulfone, perfluorodiethylsulfone, fluoromethyl-n-propylsulfone, difluoromethyl-n-propylsulfone Trifluoromethyl-n-propylsulfone, fluoromethylisopropylsulfone, difluoromethylisopropylsulfone, trifluoromethylisopropylsulfone, trifluoroethyl-n-propylsulfone, trifluoroethylisopropylsulfone, pentafluoroethyl-n-propylsulfone, Pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone Emissions, pentafluoroethyl -n- butyl sulfone, pentafluoroethyl -t- butyl sulfone, and the like.

  Among them, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone , Monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoro Ethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl isopropyl sulfone, tri Ruoroechiru -n- butyl sulfone, trifluoroethyl -t- butyl sulfone, trifluoromethyl -n- butyl sulfone, trifluoromethyl -t- butyl sulfone is preferred because a higher high output ionic conductivity.

The amount of the sulfone compound is usually 3% by mass or more, more preferably 5% by mass or more, still more preferably 8% by mass or more, and preferably 40% by mass in 100% by mass of the non-aqueous solvent. Hereinafter, it is more preferably 35% by mass or less, and further preferably 30% by mass or less. Within this range, durability improvement effects such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be set to an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging an aqueous electrolyte battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

These non-aqueous solvents may be used alone or in combination of two or more, but it is preferable to use in combination of two or more compounds. For example, a high-permittivity solvent such as a cyclic carbonate not containing a fluorine atom, a cyclic carbonate containing a fluorine atom, or a cyclic carboxylic acid ester, and a low viscosity solvent such as a chain carbonate or a chain carboxylic acid ester are used in combination. It is preferable to do this.
One preferable combination of the non-aqueous solvents is a combination mainly composed of ethylene carbonate and chain carbonate. Among them, the total of ethylene carbonate and chain carbonate in the non-aqueous solvent is usually 70% by volume or more, preferably 80% by volume or more, more preferably 90% by volume or more, and ethylene carbonate and chain carbonate. The ratio of ethylene carbonate to the total is usually 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and usually 50% by volume or less, preferably 35% by volume or less. Use of a combination of these non-aqueous solvents is preferable because the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent is improved.

Specific examples of preferred combinations of ethylene carbonate and chain carbonate include ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate and ethyl Examples include methyl carbonate, ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

A combination in which propylene carbonate is further added to the combination of these ethylene carbonates and chain carbonates is also a preferable combination.
In the case of containing propylene carbonate, the volume ratio of ethylene carbonate to propylene carbonate (ethylene carbonate / propylene carbonate) is preferably 1.0 or more, more preferably 1.2 or more, and particularly preferably 1.5 or more. . Furthermore, the lower limit of the proportion of propylene carbonate in the entire non-aqueous solvent is usually 0.1% by volume or more, preferably 1% by volume or more, more preferably 2% by volume or more, and the upper limit is usually 20% by volume or less. Preferably it is 8 volume% or less, More preferably, it is 5 volume% or less. It is preferable to contain propylene carbonate in this concentration range because the low temperature characteristics are further excellent while maintaining the combination characteristics of ethylene carbonate and chain carbonate.

  Among the combinations of ethylene carbonate and chain carbonate, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferable. Specifically, ethylene carbonate such as ethylene carbonate and ethyl methyl carbonate, and asymmetric chains. Containing ethylene alkyl carbonates; ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, ethylene carbonate, and symmetrical chain alkyl carbonate And those containing asymmetric chain alkyl carbonates have a good balance between cycle characteristics and large current discharge characteristics. Preferred. Among them, the asymmetric chain alkyl carbonate is preferably ethyl methyl carbonate, and the alkyl group of the alkyl carbonate preferably has 1 to 2 carbon atoms.

  When diethyl carbonate is contained in the non-aqueous solvent, the lower limit of the proportion of diethyl carbonate in the total non-aqueous solvent is usually 10% by volume or more, preferably 20% by volume or more, more preferably 25% by volume. More preferably, it is 30% by volume or more, and the upper limit is usually 90% by volume or less, preferably 80% by volume or less, more preferably 75% by volume or less, and further preferably 70% by volume or less. When contained, gas generation during high-temperature storage is suppressed, which is preferable.

  In the case where dimethyl carbonate is contained in the non-aqueous solvent, the lower limit of the proportion of dimethyl carbonate in the total non-aqueous solvent is usually 10% by volume or more, preferably 20% by volume or more, more preferably 25% by volume. More preferably, it is 30% by volume or more, and the upper limit is usually 90% by volume or less, preferably 80% by volume or less, and more preferably 75% by volume or less. This is preferable. Further, in the combination mainly composed of the alkylene carbonates and the chain carbonates, other solvents may be mixed.

Another example of the preferred non-aqueous solvent is an organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, or a mixed solvent consisting of two or more organic solvents selected from the group. It occupies 40% by volume or more. The non-aqueous electrolyte using this mixed solvent is less likely to evaporate or leak when used at high temperatures. Among them, the total of ethylene carbonate and propylene carbonate in the nonaqueous solvent is 40% by volume or more, preferably 50% by volume or more, more preferably 60% by volume or more, and the volume ratio of ethylene carbonate to propylene carbonate (ethylene When a carbonate / propylene carbonate) of 1.0 or less, preferably 0.9 or less is used, the balance between cycle characteristics and high-temperature storage characteristics is generally improved.

  Another example of a preferable non-aqueous solvent is a combination mainly composed of a cyclic carbonate having a fluorine atom and a chain carbonate. Among them, the total of the cyclic carbonate having a fluorine atom and the chain carbonate in the non-aqueous solvent is preferably 60% by volume or more, more preferably 80% by volume or more, and further preferably 90% by volume or more, and the fluorine atom. The ratio of the cyclic carbonate having a fluorine atom to the total of the cyclic carbonate and the chain carbonate having 3 is 3 volume or more, preferably 5 volume% or more, more preferably 10 volume% or more, still more preferably 15 volume% or more, It is preferably 60% by volume or less, more preferably 50% by volume or less, still more preferably 40% by volume or less, and particularly preferably 35% by volume or less. When a combination of these non-aqueous solvents is used, the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent may be improved.

  For example, specific examples of preferred combinations of a cyclic carbonate having a fluorine atom and a chain carbonate include monofluoroethylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and diethyl carbonate, monofluoroethylene carbonate and ethyl methyl carbonate, and monofluoroethylene carbonate. And dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the like.

  Among the combinations of cyclic carbonates having a fluorine atom and chain carbonates, those containing asymmetric chain alkyl carbonates as chain carbonates are more preferred, and in particular, monofluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, Cycle characteristics include monofluoroethylene carbonate, symmetric chain carbonates and asymmetric chain carbonates such as fluoroethylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. And a large current discharge characteristic are preferable. Among them, the symmetric chain carbonate is preferably dimethyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.

  A combination in which a cyclic carbonate not having a fluorine atom is further added to the combination of the cyclic carbonate having a fluorine atom and the chain carbonate is also a preferable combination. Among them, the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate not having a fluorine atom in the nonaqueous solvent is preferably 10% by volume or more, more preferably 15% by volume or more, and further preferably 20% by volume or more. The ratio of the cyclic carbonate having a fluorine atom to the total of the cyclic carbonate having a fluorine atom and the cyclic carbonate having no fluorine atom is 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume. % Or more, more preferably 25% by volume or more, preferably 95% by volume or less, more preferably 85% by volume or less, still more preferably 75% by volume or less, and particularly preferably 60% by volume or less. When a cyclic carbonate having no fluorine atom is contained in this concentration range, the electrical conductivity of the electrolytic solution can be secured while forming a stable protective film on the negative electrode.

  For example, specific examples of preferable combinations of a cyclic carbonate having a fluorine atom and a cyclic carbonate having no fluorine atom and a chain carbonate include monofluoroethylene carbonate, ethylene carbonate and dimethyl carbonate, monofluoroethylene carbonate and ethylene carbonate, Diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate and ethylene Carbonate and diethyl carbonate and ethyl Cyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, propylene carbonate and dimethyl carbonate, monofluoroethylene carbonate, propylene carbonate and diethyl carbonate, monofluoroethylene carbonate and propylene carbonate And ethyl methyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, propylene carbonate and diethyl carbonate Bonate and ethyl methyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate and dimethyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate and diethyl Carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate, monofluoroethylene carbonate, ethylene carbonate and propylene carbonate -Bonate, dimethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate It is done.

Among the combinations of a cyclic carbonate having a fluorine atom and a cyclic carbonate having no fluorine atom and a chain carbonate, those containing a symmetric chain alkyl carbonate as the chain carbonate are more preferable, in particular, monofluoroethylene Carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, Ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, monofluoroethylene -Bonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate monofluoroethylene Monofluoroethylene carbonates such as carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, monofluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and symmetrical chain cars Those containing sulfonates and asymmetric linear carbonate is preferred because good balanced cycle characteristics and large-current discharge characteristics. Among them, the symmetric chain carbonate is preferably dimethyl carbonate, and the alkyl group of the chain carbonate preferably has 1 to 2 carbon atoms.
Further, when dimethyl carbonate is contained in the non-aqueous solvent, the proportion of dimethyl carbonate in the total non-aqueous solvent is preferably 10% by volume or more, more preferably 20% by volume or more, and further preferably 25% by volume or more. In particular, it is 30% by volume or more, preferably 90% by volume or less, more preferably 80% by volume or less, still more preferably 75% by volume or less, and particularly preferably 70% by volume or less. As a result, the load characteristics of the battery may be improved.

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

In the combination mainly composed of the cyclic carbonate having a fluorine atom and the chain carbonate, in addition to the cyclic carbonate having no fluorine atom, a cyclic carboxylic acid ester, a chain carboxylic acid ester, a cyclic ether, Other solvents such as chain ethers, sulfur-containing organic solvents, phosphorus-containing organic solvents, and aromatic fluorine-containing solvents may be mixed.
In this specification, the volume of the non-aqueous solvent is a measured value at 25 ° C., but the measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.

1-6. Auxiliary Agent In the non-aqueous electrolyte battery of the present invention, an auxiliary agent may be appropriately used depending on the purpose in addition to the phosphazenes represented by the general formula (1) and the compound having at least one isocyanate group in the molecule. Good. Examples of the auxiliary agent include compounds having a nitrile group shown below, an overcharge inhibitor, and other auxiliary agents.

<Compound having nitrile group>
The compound having a nitrile group is not particularly limited as long as it is a compound having a nitrile group in the molecule.
Specific examples of the compound having a nitrile group include, for example,
Acetonitrile,
Propionitrile,
Butyronitrile,
Isobutyronitrile,
Valeronitrile,
Isovaleronitrile,
Lauronitrile,
2-methylbutyronitrile,
Trimethylacetonitrile,
Hexanenitrile,
Cyclopentanecarbonitrile,
Cyclohexanecarbonitrile,
Acrylonitrile,
Methacrylonitrile,
Crotononitrile,
3-methylcrotononitrile,
2-methyl-2-butenenitryl,
2-pentenenitrile,
2-methyl-2-pentenenitrile,
3-methyl-2-pentenenitrile,
2-hexenenitrile,
Fluoroacetonitrile,
Difluoroacetonitrile,
Trifluoroacetonitrile,
2-fluoropropionitrile,
3-fluoropropionitrile,
2,2-difluoropropionitrile,
2,3-difluoropropionitrile,
3,3-difluoropropionitrile,
2,2,3-trifluoropropionitrile,
3,3,3-trifluoropropionitrile,
3,3′-oxydipropionitrile,
3,3′-thiodipropionitrile,
1,2,3-propanetricarbonitrile,
1,3,5-pentanetricarbonitrile,
Compounds having one nitrile group such as pentafluoropropionitrile;
Malononitrile,
Succinonitrile,
Glutaronitrile,
Adiponitrile,
Pimelonitrile,
Suberonitrile,
Azeronitrile,
Sevacononitrile,
Undecandinitrile,
Dodecanedinitrile,
Methylmalononitrile,
Ethylmalononitrile,
Isopropylmalononitrile,
tert-butylmalononitrile,
Methylsuccinonitrile,
2,2-dimethylsuccinonitrile,
2,3-dimethylsuccinonitrile,
2,3,3-trimethylsuccinonitrile,
2,2,3,3-tetramethylsuccinonitrile,
2,3-diethyl-2,3-dimethylsuccinonitrile,
2,2-diethyl-3,3-dimethylsuccinonitrile,
Bicyclohexyl-1,1-dicarbonitrile,
Bicyclohexyl-2,2-dicarbonitrile,
Bicyclohexyl-3,3-dicarbonitrile,
2,5-dimethyl-2,5-hexanedicarbonitrile,
2,3-diisobutyl-2,3-dimethylsuccinonitrile,
2,2-diisobutyl-3,3-dimethylsuccinonitrile,
2-methylglutaronitrile,
2,3-dimethylglutaronitrile,
2,4-dimethylglutaronitrile,
2,2,3,3-tetramethylglutaronitrile,
2,2,4,4-tetramethylglutaronitrile,
2,2,3,4-tetramethylglutaronitrile,
2,3,3,4-tetramethylglutaronitrile,
Maleonitrile,
Fumaronitrile,
1,4-dicyanopentane,
2,6-dicyanoheptane,
2,7-dicyanooctane,
2,8-dicyanononane,
1,6-dicyanodecane,
1,2-didianobenzene,
1,3-dicyanobenzene,
1,4-dicyanobenzene,
3,3 ′-(ethylenedioxy) dipropionitrile,
A compound having two nitrile groups such as 3,3 ′-(ethylenedithio) dipropionitrile; 1,2,3-tris (2-cyanoethoxy) propane;
Compounds having three nitrile groups such as tris (2-cyanoethyl) amine;
Methyl cyanate,
Ethyl cyanate,
Propyl cyanate,
Butyl cyanate,
Pentyl cyanate,
Hexyl cyanate,
Cyanate compounds such as heptyl cyanate;
Methyl thiocyanate,
Ethyl thiocyanate,
Propyl thiocyanate,
Butyl thiocyanate,
Pentyl thiocyanate,
Hexyl thiocyanate,
Heptyl thiocyanate,
Methanesulfonyl cyanide,
Ethanesulfonyl cyanide,
Propanesulfonyl cyanide,
Butanesulfonyl cyanide,
Pentanesulfonylcyanide,
Hexanesulfonyl cyanide,
Heptanesulfonyl cyanide,
Methylsulfurocyanidate,
Ethylsulfuranidate,
Propylsulfurocyanidate,
Butyl sulfrocyanidate,
Pentylsulfurocyanidate,
Hexylsulfurocyanidate,
Sulfur-containing compounds such as heptylsulfurocyanidate;
Cyanodimethylphosphine,
Cyanodimethylphosphine oxide,
Methyl cyanomethylphosphinate,
Methyl cyanomethylphosphite,
Dimethylphosphinic cyanide,
Dimethyl phosphinic acid cyanide,
Dimethyl cyanophosphonate,
Dimethyl cyanophosphonite,
Cyanomethyl methylphosphonate,
Cyanomethyl methylphosphonite,
Cyanodimethyl phosphate,
Phosphorus-containing compounds such as cyanodimethyl phosphite;
Etc.

Of these, lauronitrile, crotononitrile, 3-methylcrotononitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, fumaronitrile It is preferable from the point of improvement.
A compound having a nitrile group may be used alone or in combination of two or more in any combination and ratio. The compounding amount of the compound having a nitrile group with respect to the whole non-aqueous electrolyte solution of the present invention is not limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. 001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Let When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

<Overcharge prevention agent>
In the non-aqueous electrolyte solution of the present invention, an overcharge inhibitor can be used in order to effectively prevent the battery from bursting or igniting when the non-aqueous electrolyte battery is overcharged.
As an overcharge inhibitor, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran; 2-fluorobiphenyl, Partially fluorinated products of the above aromatic compounds such as o-cyclohexylfluorobenzene and p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole and the like And a fluorine-containing anisole compound. Of these, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, terphenyl partially hydrogenated, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferable. These may be used alone or in combination of two or more. When two or more kinds are used in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, Using at least one selected from aromatic compounds not containing oxygen, such as t-amylbenzene, and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether, dibenzofuran, and the like is an overcharge prevention property and a high temperature storage property. From the standpoint of balance.

The amount of the overcharge inhibitor is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The overcharge inhibitor is preferably 0.1% by mass or more and 5% by mass or less in 100% by mass of the non-aqueous electrolyte solution. If it is this range, it will be easy to fully express the effect of an overcharge inhibiting agent, and it will be easy to avoid the situation where the battery characteristics, such as a high temperature storage characteristic, fall. The overcharge inhibitor is more preferably 0.2% by mass or more, further preferably 0.3% by mass or more, particularly preferably 0.5% by mass or more, and more preferably 3% by mass or less, still more preferably. Is 2% by mass or less.

<Other auxiliaries>
Other known auxiliary agents can be used in the non-aqueous electrolyte solution of the present invention. Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, anhydrous Carboxylic anhydrides such as itaconic acid, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; 2,4,8,10-tetraoxaspiro [5.5 ] Spiro compounds such as undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; ethylene sulfite, 1,3-propane sultone, 1-fluoro-1,3- Propane sultone, 2-fluoro-1,3-propane sultone, 3-ph Oro-1,3-propane sultone, 1-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro -1-propene-1,3-sultone, 1,4-butanesultone, 1-butene-1,4-sultone, 3-butene-1,4-sultone, methyl fluorosulfonate, ethyl fluorosulfonate, methanesulfonic acid Sulfur-containing compounds such as methyl, ethyl methanesulfonate, busulfan, sulfolene, diphenylsulfone, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2 -Piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-me Nitrogen-containing compounds such as Rusukushin'imido; heptane, octane, nonane, decane, hydrocarbon compounds cycloheptane, etc., fluorobenzene, difluorobenzene, hexafluorobenzene, fluorinated aromatic compounds such as benzotrifluoride, and the like. These may be used alone or in combination of two or more. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved.

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

  The non-aqueous electrolyte solution described above includes those existing inside the non-aqueous electrolyte battery according to the present invention. Specifically, the components of the non-aqueous electrolyte solution such as lithium salt, solvent, and auxiliary agent are separately synthesized, and the non-aqueous electrolyte solution is prepared from what is substantially isolated by the method described below. In the case of a nonaqueous electrolyte solution in a nonaqueous electrolyte battery obtained by pouring into a separately assembled battery, the components of the nonaqueous electrolyte solution of the present invention are individually placed in the battery, In order to obtain the same composition as the non-aqueous electrolyte solution of the present invention by mixing in a non-aqueous electrolyte battery, the compound constituting the non-aqueous electrolyte solution of the present invention is further generated in the non-aqueous electrolyte battery. The case where the same composition as the aqueous electrolyte is obtained is also included.

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

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

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

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

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

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

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

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

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

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

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

Particularly preferred representative compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), Li _4/5 Ti _11/5 O in (c). ₄ . As for the structure of Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.
<Physical properties of carbonaceous materials>
When using a carbonaceous material as a negative electrode active material, it is desirable to have the following physical properties.

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

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

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

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

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

The measurement of the Raman spectrum, using a Raman spectrometer (manufactured by JASCO Corporation Raman spectrometer), the sample is naturally dropped into the measurement cell and filled, and while irradiating the sample surface in the cell with argon ion laser light, This is done by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity IA of a peak PA around 1580 cm ^-1, and measuring the intensity IB of the peak PB around 1360 cm ^-1, and calculates the intensity ratio R (R = IB / IA) .

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half-width analysis: Background processing ・ Smoothing processing: Simple average, 5 points of convolution (BET specific surface area)
BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · g ^-1 or more, 0.7 m ² · g ^-1 or more, 1. 0 m ² · g ^-1 or more, and particularly preferably 1.5 m ² · g ^-1 or more, generally not more than 100 m ² · g ^-1, preferably 25 m ² · g ^-1 or less, 15 m ² · More preferably, g ⁻¹ or less is 10 m ^2.
-G- ¹ or less is particularly preferable.

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

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

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

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

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

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample up to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the mass at that time and the mass of the sample.
(Orientation ratio)
The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more, more preferably 0.015 or more, and usually 0.67 or less. When the orientation ratio is in the above range, excellent high-density charge / discharge characteristics can be ensured. The upper limit of the above range is the theoretical upper limit value of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. 0.47 g of sample diameter 1
X-ray diffraction is measured by setting the molded body obtained by filling a 7mm molding machine and compressing it with 58.8MN · m ^{-2 so} that it is flush with the surface of the sample holder for measurement. . From the (110) diffraction and (004) diffraction peak intensities of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree / measurement range and step angle / measurement time:
(110) face: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) face: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds (aspect ratio (powder))
The aspect ratio of the carbonaceous material is usually 1 or more and usually 10 or less, preferably 8 or less, and more preferably 5 or less. Within the above range, streaking during electrode plate formation is suppressed and more uniform coating is possible, so that excellent high current density charge / discharge characteristics can be ensured. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the carbonaceous material.

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

<Configuration and production method of negative electrode>
Any known method can be used for producing the electrode as long as the effects of the present invention are not significantly impaired. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to the negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.

In the case of using an alloy-based material, a method of forming a thin film layer (negative electrode active material layer) containing the above-described negative electrode active material by a technique such as vapor deposition, sputtering, or plating is also used.
(Current collector)
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the negative electrode current collector include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.

  In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.

The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less, from the viewpoint of securing battery capacity and handling properties.
(Thickness ratio between current collector and negative electrode active material layer)
The ratio of the thickness of the current collector to the negative electrode active material layer is not particularly limited, but the value of “(the thickness of the negative electrode active material layer on one side immediately before the nonaqueous electrolyte injection) / (thickness of the current collector)” However, 150 or less is preferable, 20 or less is more preferable, 10 or less is particularly preferable, 0.1 or more is preferable, 0.4 or more is further preferable, and 1 or more is particularly preferable. When the ratio of the thickness of the current collector to the negative electrode active material layer is in the above range, battery capacity can be secured and heat generation of the current collector during high current density charge / discharge can be suppressed.

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

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

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

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

In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the thickener and slurry it using a latex such as SBR. In addition, these solvents may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.
(Thickener)
A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

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

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

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

(Surface coating of negative electrode plate)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said negative electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.
2-2. Positive electrode <Positive electrode active material>
The positive electrode active material used for the positive electrode is described below.

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

The transition metal of the lithium transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu or the like, and specific examples include lithium / cobalt composite oxide such as LiCoO ₂ or LiNiO ₂ . Lithium / nickel composite oxide, LiMnO ₂ , LiMn ₂ O ₄ , L
Li ₂ -Mn composite oxides such as i ₂ MnO ₄ , some of transition metal atoms that are the main components of these lithium transition metal composite oxides are Na, K, B, F, Al, Ti, V, Cr, Mn, Examples include those substituted with other elements such as Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. Specific examples of the substituted ones include, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiNi _0.45 Co _0.10 Al _0.45 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _{4 and the} like.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ). ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other elements.

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

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

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

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

In the present invention, a material in which a material having a composition different from that of the positive electrode active material is attached to the surface of the positive electrode active material is also referred to as a “positive electrode active material”.
(shape)
Examples of the shape of the particles of the positive electrode active material include a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, and a column shape as conventionally used. Moreover, primary particles may aggregate to form secondary particles.

(Tap density)
The tap density of the positive electrode active material is preferably 0.5 g / cm ³ or more, more preferably 0.8
g / cm ³ or more, more preferably 1.0 g / cm ³ or more. When the tap density of the positive electrode active material is within the above range, the amount of dispersion medium and the necessary amount of conductive material and binder required for forming the positive electrode active material layer can be suppressed. As a result, the filling rate of the positive electrode active material and the battery Capacity can be secured. By using a complex oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. In general, the tap density is preferably as large as possible, and there is no particular upper limit. However, the tap density is preferably 4.0 g / cm ³ or less, more preferably 3.7 g / cm ³ or less, and further preferably 3.5 g / cm ³ or less. When it is within the above range, it is possible to suppress a decrease in load characteristics.

In the present invention, the tap density is defined as the powder packing density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is put in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. Ask.
(Median diameter d50)
The median diameter d50 of the positive electrode active material particles (secondary particle diameter when primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably. Is 0.8 μm or more, most preferably 1.0 μm or more, and the upper limit is preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, and most preferably 22 μm or less. While being in the above range, a high tap density product can be obtained and the battery performance can be prevented from deteriorating. On the other hand, when creating a positive electrode for a battery, that is, when slurrying an active material, a conductive material, a binder, etc. with a solvent, Problems such as streaking can be prevented. Here, by mixing two or more kinds of the positive electrode active materials having different median diameters d50, it is possible to further improve the filling property when forming the positive electrode.

In the present invention, the median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. When LA-920 manufactured by HORIBA is used as a particle size distribution meter, a 0.1% by mass sodium hexametaphosphate aqueous solution is used as a dispersion medium for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. Measured.
(Average primary particle size)
When primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.8 μm. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and most preferably 2 μm or less. When it is in the above range, powder filling property and specific surface area can be ensured and deterioration of battery performance can be suppressed, while reversibility of charge and discharge can be ensured by obtaining appropriate crystallinity. .

In the present invention, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles and obtained by taking the average value. It is done.
(BET specific surface area)
The BET specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more, more preferably 0.00.
2 m ² / g or more, more preferably 0.3 m ² / g or more, and the upper limit is 50 m ² / g or less.
Preferably it is 40 m < ² > / g or less, More preferably, it is 30 m < ² > / g or less. When the BET specific surface area is in the above range, the battery performance can be secured and the applicability of the positive electrode active material can be kept good.

In the present invention, the BET specific surface area is determined by subjecting the sample to preliminary drying at 150 ° C. for 30 minutes under a nitrogen flow using a surface area meter (for example, a fully automated surface area measuring device manufactured by Okura Riken),
It is defined by a value measured by a nitrogen adsorption BET one-point method using a gas flow method using a nitrogen-helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen with respect to atmospheric pressure is 0.3.
(Method for producing positive electrode active material)
As a manufacturing method of the positive electrode active material, a general method is used as a manufacturing method of the inorganic compound. In particular, various methods are conceivable for preparing a spherical or elliptical active material. For example, a transition metal source material is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, and after drying as necessary, a Li source such as LiOH, Li ₂ CO ₃ , LiNO _{3 and the} like is added and fired at a high temperature to obtain an active material. .

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

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

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

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

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

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

(Slurry forming solvent)
As the solvent for forming the slurry, the positive electrode active material, the conductive material, the binder, and a solvent capable of dissolving or dispersing the thickener used as necessary may be used. There is no restriction, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of the organic medium include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone. Esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N, N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) Amides such as dimethylformamide and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide.

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

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

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

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

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

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

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

The material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. Among them, a resin, glass fiber, inorganic material, etc. formed of a material that is stable with respect to the non-aqueous electrolyte solution of the present invention is used, and a porous sheet or a nonwoven fabric-like material having excellent liquid retention properties is used. Is preferred.
As materials for the resin and glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

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

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

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

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

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

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

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

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

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples and comparative examples, and may be arbitrarily set without departing from the gist of the present invention. It can be implemented with deformation.
<Example A>
<Explanation of test operation>
[Production of positive electrode]
94% by mass of lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, 3% by mass of acetylene black as a conductive material, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder, an N-methylpyrrolidone solvent The slurry was mixed with a disperser. This was uniformly applied to both sides of the aluminum foil, dried, and then pressed to obtain a positive electrode.

[Manufacture of negative electrode]
A negative electrode was obtained by mixing 94 parts by mass of graphite powder as a negative electrode active material and 6 parts by mass of PVdF, adding N-methylpyrrolidone into a slurry, and applying and drying on one side of a current collector made of copper. .
[Manufacture of lithium secondary batteries]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, the positive electrode, the separator, and the negative electrode. The battery element thus obtained was wrapped in a cylindrical aluminum laminate film, injected with an electrolyte described later, and then vacuum sealed to produce a sheet-like non-aqueous electrolyte secondary battery. Furthermore, in order to improve the adhesion between the electrodes, the sheet-like battery was sandwiched between glass plates and pressurized.

[Capacity evaluation test]
In a constant temperature bath at 25 ° C., the battery was constant current-constant voltage charged to 4.1 V with a current corresponding to 0.2 C (hereinafter referred to as “CCCV charging” as appropriate) and then discharged to 3 V at 0.2 C. This was repeated three times to form an initial formation. Subsequently, after CCCV charge to 4.2V at 0.2C, it discharged again to 3V at 0.2C, and the initial discharge capacity was calculated | required. The cut current during charging was set to 0.05C. After the initial capacity evaluation of the battery was completed, the battery was immersed in an ethanol bath to measure the mass, and the amount of gas generated from the mass change before and after the capacity evaluation test was determined. This is the initial gas amount.

Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and for example, 0.2C represents a current value of 1/5 thereof.
[High temperature storage characteristics evaluation test]
After the initial capacity evaluation, the non-aqueous electrolyte battery was again CCCV charged to 4.2 V at 0.2 C (0.05 C cut), and then stored at 85 ° C. for 48 hours at a high temperature. It was. After the battery was sufficiently cooled, it was immersed in an ethanol bath to measure the mass, and the amount of gas generated from the mass change before and after storage was determined. This was defined as the amount of stored gas. Next, it was discharged to 3 V at 0.2 C at 25 ° C. After that, CCCV charge (0.05C cut) to 4.2V at 0.2C, discharge to 3V at 0.5C, measure 0.2C discharge capacity after high temperature storage characteristics test, 0.2 C capacity.

[Cycle characteristic evaluation test]
After the initial capacity evaluation, the non-aqueous electrolyte battery was placed in a constant temperature bath at 60 ° C. and charged at a constant current of up to 4.2 V at 2 C, and then the process of constant current discharge at 2 C was performed as 150 cycles. . Then, the discharge capacity retention ratio was obtained from the formula of (discharge capacity at 150th cycle) ÷ (discharge capacity at the first cycle) × 100.

<Example 1, Comparative example 2, 4-5>
Under a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC), phosphazenes (a compound in which the substituents X1 to X5 are fluorine atoms and X6 is an ethoxy group in the above general formula (1) (ethoxypentafluoro A basic electrolyte solution was prepared by dissolving LiPF ₆ as an electrolyte at a rate of 1.0 mol / L in a mixed solvent (mixing volume ratio 3: 6: 1) composed of cyclotriphosphazene (hereinafter EtPFPN). EtPFPN was 12% by mass with respect to the mass.) The basic electrolytic solution was mixed with a compound described in Table 1 to obtain electrolytic solutions used in Example 1 and Comparative Examples 2 and 4 to 5, respectively.

Using the obtained nonaqueous electrolytic solution, a lithium secondary battery was produced according to the above-described method, and an initial capacity evaluation test, a high temperature storage characteristic evaluation test, and a cycle test were performed. The results are shown in Table 1.
<Comparative Examples 1 and 3>
Under a dry argon atmosphere, LiPF ₆ as an electrolyte is dissolved in a mixed solvent of EC and EMC (mixing volume ratio 3: 7) at a rate of 1.0 mol / L to obtain a basic electrolytic solution. A secondary battery was prepared and evaluated in the same manner as in Example 1 except that was used as a nonaqueous electrolyte. The results are shown in Table 1.

From Table 1, when the non-aqueous electrolyte solution of Example 1 according to the present invention is used, the phosphazenes represented by the general formula (1) and the compound having at least one isocyanate group in the molecule are not added ( Compared to Comparative Example 1), it can be seen that the initial storage capacity and the post-storage capacity are maintained at a level that does not cause a problem in practice, and the amount of the high-temperature storage gas is remarkably reduced, the cycle characteristics are improved, and excellent. When only phosphazenes are contained (Comparative Example 2), the initial gas amount is large, and the cycle characteristics are also lower than those of Comparative Example 1. In addition, when only the compound having an isocyanate group was added (Comparative Example 3), no improvement in the storage gas amount and the cycle characteristics was observed as compared with Example 1. Further, when phosphazenes and vinylene carbonate were added (Comparative Examples 4 and 5), the effect of reducing the amount of stored cogas and improving the cycle characteristics was not seen as compared with Example 1.

<Example B>
<Manufacture of positive electrode>
94% by mass of lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, 3% by mass of acetylene black as a conductive material, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder, an N-methylpyrrolidone solvent The slurry was mixed with a disperser. This was uniformly applied to both sides of the aluminum foil, dried, and then pressed to obtain a positive electrode.

<Manufacture of negative electrode>
100 parts by weight of graphite powder as the negative electrode active material, 1 part by weight of aqueous dispersion of sodium carboxymethyl cellulose (concentration of 1% by weight of sodium carboxymethyl cellulose) as the thickener and binder, respectively, and aqueous dispersion of styrene-butadiene rubber 1 part by mass (concentration of styrene-butadiene rubber 50% by mass) was added and mixed with a disperser to form a slurry. The slurry was uniformly applied to one side of the copper foil, dried, and then pressed to obtain a negative electrode.

<Manufacture of secondary batteries>
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, the positive electrode, the separator, and the negative electrode to produce a battery element. After inserting this battery element into a bag made of an aluminum laminate film with positive and negative terminals protruding, a non-aqueous electrolyte solution is injected into the bag, vacuum-sealed, and a sheet-like non-aqueous electrolyte solution A battery was produced.

[Initial capacity evaluation]
A non-aqueous electrolyte battery is pressed between glass plates at 25 ° C. and charged at a constant current of up to 4.1 V at a current equivalent to 0.2 C, and then discharged to 3 V at a constant current of 0.2 C. Then, after CCCV charge (0.05 C cut) to 4.33 V with a current corresponding to 0.2 C, the battery was stabilized by discharging to 0.2 V at 3 C. Next, after CCCV charge (0.05 C cut) to 4.33 V at 0.2 C, the battery was discharged again to 3 V at 0.5 C to determine the initial capacity.

[High temperature storage characteristics evaluation test]
After performing CCCV charge (0.05C cut) to 4.33V again, high temperature preservation | save was performed on the conditions of 85 degreeC and 24 hours. After the battery was sufficiently cooled, it was immersed in an ethanol bath to measure the mass, and the amount of gas generated from the mass change before and after storage was determined. Next, discharge at 25 ° C. to 3 V at 0.2 C, measure the remaining capacity after the high temperature storage characteristics test, determine the ratio of the remaining capacity to the initial discharge capacity, this is the remaining capacity (%) after high temperature storage did. Again, CCCV charge (0.05C cut) to 4.33V, discharge to 3V at 0.2C, measure 0.2C discharge capacity after high temperature storage characteristics test, 0.2C discharge capacity relative to initial discharge capacity The ratio was determined as the recovery capacity (%) after high-temperature storage.

<Example 2, Comparative Examples 6-8>
In a dry argon atmosphere, a mixture of monofluoroethylene carbonate (MFEC) and dimethyl carbonate (DMC) (mass ratio 30:70), VC1 mass% and adiponitrile (AdpCN) 1 mass% as content in the non-aqueous electrolyte solution Next, fully dried LiPF6 was dissolved at a rate of 1 mol / L to prepare a basic electrolyte solution. The basic electrolyte solution was mixed with the compounds described in Table 2 to obtain electrolyte solutions used in Example 2 and Comparative Examples 6 to 8, respectively.

Using the obtained nonaqueous electrolytic solution, a lithium secondary battery was prepared according to the above-described method, and an initial capacity evaluation test and a high temperature storage characteristic evaluation test were performed. The results are shown in Table 2.
<Example 3, Comparative Examples 9 to 10>
Under a dry argon atmosphere, a mixture of EC, MFEC, and DMC (mass ratio 15:15:70) was mixed with VC1 mass% and AdpCN 1 mass% as the content in the non-aqueous electrolyte, and then fully dried LiPF6 Was dissolved at a rate of 1 mol / L to prepare a basic electrolyte. The basic electrolyte solution was mixed with the compounds shown in Table 3 to obtain electrolyte solutions used in Example 3 and Comparative Examples 9 to 10, respectively.
Using the obtained non-aqueous electrolyte battery, an initial capacity evaluation and a high-temperature storage test were performed. The evaluation results are shown in Table 3.

  From Table 2, when the non-aqueous electrolyte solution of Example 2 according to the present invention is used, the phosphazenes represented by the general formula (1) and the compound having at least one isocyanate group in the molecule are not added. Compared to (Comparative Example 6), it can be seen that the amount of gas generated during high-temperature storage is low, and the residual / recovery capacity after high-temperature storage is excellent. Further, when the phosphazenes represented by the general formula (1) or a compound having at least one isocyanate group in the molecule is added alone (Comparative Examples 7 to 8), the amount of gas generated during high-temperature storage・ It can be seen that the remaining capacity improvement effect is insufficient.

  From Table 3, when the nonaqueous electrolytic solution of Example 3 according to the present invention is used, the phosphazenes represented by the general formula (1) and the compound having at least one isocyanate group in the molecule are not added. Compared to (Comparative Example 9), it can be seen that the amount of gas generated during high-temperature storage is low, and the residual / recovery capacity after high-temperature storage is excellent. It can also be seen that when the compound having at least one isocyanate group in the molecule is added alone (Comparative Example 10), the effect of improving the amount of gas generated and the remaining capacity during high-temperature storage is insufficient.

According to the non-aqueous electrolyte of the present invention, the initial capacity is hardly lowered, and the cycle characteristics of the non-aqueous electrolyte battery and capacity deterioration during high-temperature storage can be improved. Therefore, the non-aqueous electrolyte solution of the present invention and the non-aqueous electrolyte battery using the same can be used for various known applications. Specific examples include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, etc. , Walkie Talkie, Electronic Notebook, Calculator, Memory Card, Portable Tape Recorder, Radio, Backup Power Supply, Motor, Automobile, Motorcycle, Motorbike, Bicycle, Lighting Equipment, Toy, Game Equipment, Clock, Electric Tool, Strobe, Camera, Load Examples include leveling power sources and natural energy storage power sources.

Claims (11)

A non-aqueous electrolyte containing an electrolyte and a non-aqueous solvent, wherein the non-aqueous electrolyte is at least (A) phosphazenes represented by the following general formula (1), and
(B) A non-aqueous electrolyte containing a compound having at least one isocyanate group in the molecule.

(In the general formula (1), X ^{1 to} X ⁶ each independently represent at least one selected from the group of a halogen atom, an alkyl group, an aryl group, an alkoxy group or an aryloxy group, and are the same. May be different.)   The phosphazene represented by the general formula (1) is contained in an amount of 0.01 to 50% by mass in the non-aqueous electrolyte solution.   The phosphazene represented by the general formula (1) is contained in an amount of 3 to 50% by mass in the non-aqueous electrolyte solution.   The phosphazene represented by the general formula (1) is contained in an amount of 0.01 to 5% by mass in the non-aqueous electrolyte solution. In the above general formula (1), at least one of X ^{1 to} X ⁶ is a halogen atom, and at least one of X ^{1 to} X ⁶ is an alkoxy group or an aryloxy group. Item 5. The nonaqueous electrolyte battery according to any one of Items 1 to 4. The non-aqueous electrolyte solution according to any one of claims 1 to 5, wherein the compound (B) is represented by the following general formula (2).
(X ⁷ ) − (N═C═O) _n (2)
(In the general formula (2), X ⁷ represents an organic group composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, and , N represents an integer of 1 to 5. The non-aqueous system according to any one of claims 1 to 6, wherein in the general formula (2), X ⁷ represents an organic group having 2 to 14 carbon atoms, and n is 2 or more. Electrolytic solution.   The non-aqueous electrolyte solution according to any one of claims 1 to 7, wherein the compound (B) is contained in an amount of 0.01 to 10% by mass in the non-aqueous electrolyte solution.   In the non-aqueous electrolyte, at least one compound selected from the group consisting of a cyclic carbonate having a fluorine atom, a cyclic carbonate having a carbon-carbon unsaturated bond, a monofluorophosphate, and a difluorophosphate is further added. The non-aqueous electrolyte solution according to claim 1, wherein the non-aqueous electrolyte solution is contained.   The cyclic carbonate having a fluorine atom is at least one compound selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate, and has a carbon-carbon unsaturated bond. The non-aqueous electrolyte solution according to claim 9, wherein the cyclic carbonate is at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate.   11. A non-aqueous electrolyte battery comprising a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is a non-aqueous electrolyte solution according to claim 1. A non-aqueous electrolyte battery characterized by the above.