JP6098062B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery using the same - Google Patents

Description

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

  Lithium non-aqueous electrolyte secondary batteries that use lithium-containing transition metal oxides as the positive electrode and non-aqueous solvent as the electrolyte can achieve high energy density, so from small power sources such as mobile phones and laptop computers to automobiles It is applied to a wide range of applications, from large power supplies for railways and road leveling. However, the demand for higher performance of non-aqueous electrolyte batteries in recent years is increasing, and there is a strong demand for improvement of various characteristics.

Lithium non-aqueous electrolyte secondary batteries include cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carboxyls such as γ-butyrolactone and γ-valerolactone. Acid esters; chain carboxylic acid esters such as methyl acetate, ethyl acetate, and methyl propionate; and LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) _2, etc. A non-aqueous electrolyte containing a solute is used.

  In the non-aqueous electrolyte secondary battery using such a non-aqueous electrolyte, the reactivity varies depending on the composition of the non-aqueous electrolyte, and thus the battery characteristics are greatly changed by the non-aqueous electrolyte. In order to improve battery characteristics such as load characteristics, cycle characteristics and storage characteristics of non-aqueous electrolyte secondary batteries, and to improve battery safety during overcharge, various studies have been conducted on non-aqueous solvents and electrolytes. Has been made.

Patent Document 1 reports that the use of a halogen-containing cyclic carbonate as a non-aqueous electrolyte component lowers the freezing point and improves cycle characteristics.
Patent Document 2 reports that by dissolving a low molecular weight isocyanate compound in an organic electrolyte, a reaction layer is formed at the electrode interface, and excellent cycle stability can be obtained.
Patent Document 3 discloses a non-aqueous electrolyte 2 in which a positive electrode contains a positive electrode active material coated with a phosphate, and an electrolytic solution contains an electrolytic solution containing a non-aqueous solvent, an electrolyte salt, and an isocyanate compound. It has been reported that by using a secondary battery, the effect of suppressing swelling during high-temperature storage can be obtained.

  Patent Document 4 reports that by using a non-aqueous electrolyte battery containing 50 to 1000 ppm of water in the positive electrode and the electrolyte containing an isocyanate compound and an aromatic compound, battery characteristics during high-temperature cycles are improved. Has been.

Japanese Patent Laid-Open No. 7-240232 JP 2005-259641 A JP 2011-014379 A JP 2011-028860 A

However, the demand for improving the characteristics of lithium non-aqueous electrolyte secondary batteries in recent years has been increasing, and it has all the performances such as energy density, output performance, life, high temperature resistance, and low temperature characteristics at a high level. It is sought, but not yet achieved. The durability performance including the cycle characteristics and the performance such as capacity, resistance, and output characteristics are in a trade-off relationship, and there is a problem that the overall performance balance is poor.

The present invention has been made in view of the above-described problems. That is, with respect to a lithium non-aqueous electrolyte secondary battery, an object is to provide a battery having a good balance of overall performance with respect to performance such as durability and capacity, resistance, and output characteristics.
As a result of intensive studies, the inventors of the present invention can solve the above problems by using a non-aqueous electrolytic solution containing a fluorine ethylene carbonate derivative and a specific compound having a carbon-nitrogen multiple bond. In addition, the present inventors have found that the above-mentioned problems can be solved by including a specific other compound in the non-aqueous electrolyte solution, and have completed the present invention described later.

Further, the present invention, which will be described later, finds that the above-mentioned problems can be solved by using a specific positive electrode in combination with a non-aqueous electrolyte solution containing a fluorine ethylene carbonate derivative and a specific compound having a carbon-nitrogen multiple bond. It was completed.
The gist of the first aspect of the present invention is as follows.
In a non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent,
(A) at least one compound selected from the group consisting of a carbonate having a carbon-carbon unsaturated bond and a compound represented by the following general formula (1);
(B) a fluorine-containing ethylene carbonate derivative;
(C) a compound represented by the following general formula (2),
And a non-aqueous electrolyte solution.

(In the above formula (1), M is —O— or —NR ² —, and R ² is hydrogen or an optionally branched hydrocarbon group having 10 or less carbon atoms. R ¹ is a substituent. And a hydrocarbon group having 10 or less carbon atoms which may have a branched chain.)

(In the above formula (2), R ³ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms. W is a functional group having a molecular weight of 50 or less having a carbon-nitrogen multiple bond. n represents an integer of 1 to 4, and when n is an integer of 2 or more, the plurality of Ws may be the same functional group or different functional groups.
The fluorine-containing ethylene carbonate derivative is preferably 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one.
Moreover, it is preferable that the compound shown by the said General formula (2) is a compound shown by following General formula (3).

X-R ⁴ -X (3)
(R ⁴ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms. X is a cyano group or an isocyanato group.)
In addition, the compound represented by the general formula (2) is 1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-.
Diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methyl = isocyanate), or bicyclo [2.2.1] heptane-2,6-diylbis (methyl = isocyanate), 2,4,4 -Trimethylhexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate are preferable.

Further, in the compound represented by the general formula (1), ^{R 1} is _{-CH 2 -CH 2 -, - CH} 2 -CH 2 -CH 2 -, - CH = CH -, - CH = C (CH 3) It is preferable to represent a hydrocarbon group selected from the group consisting of —, —CH ₂ —C (═CH ₂ ) — and a hydrocarbon group represented by the following structural formula (4).

In the compound represented by the general formula (1), M preferably represents an organic group selected from the group consisting of —O—, —NH—, and —N (CH ₃ ) —. The compound represented by the general formula (1) is preferably succinic anhydride or maleic anhydride.

The carbonate having a carbon-carbon unsaturated bond is preferably at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate.
Further, at least one compound selected from the group consisting of the carbonate having a carbon-carbon unsaturated bond and the compound represented by the general formula (1) is added to the non-aqueous electrolyte solution in an amount of 0.
It is preferable to contain 001 mass% or more and 10 mass% or less.

Moreover, it is preferable to contain the said fluorine-containing ethylene carbonate derivative in 0.001 mass% or more and 10 mass% or less in nonaqueous electrolyte solution.
Moreover, it is preferable to contain 0.001 mass% or more and 10 mass% or less of the compound shown by the said General formula (2) in nonaqueous electrolyte solution.
Another aspect of the present invention is a non-aqueous electrolyte secondary battery comprising at least a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution. The aqueous electrolyte is a non-aqueous electrolyte secondary battery characterized in that it is any one of the non-aqueous electrolytes described above.

The gist of the second present invention is as follows.
Non-aqueous electrolysis comprising at least a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolytic solution including a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent In liquid secondary batteries,
The positive electrode contains a lithium manganese composite oxide having a spinel structure,
The non-aqueous electrolyte solution is
(A) a fluorine-containing ethylene carbonate derivative;
(B) a compound represented by the following general formula (2),
And a non-aqueous electrolyte secondary battery.

(In the above formula (2), R ³ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms. W is a functional group having a molecular weight of 50 or less having a carbon-nitrogen multiple bond. n represents an integer of 1 to 4, and when n is an integer of 2 or more, the plurality of Ws may be the same functional group or different functional groups.
Moreover, it is preferable that the positive electrode containing the lithium manganese composite oxide further contains a lithium nickel composite oxide having a layered structure.

The fluorine-containing ethylene carbonate derivative is preferably 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one.
Moreover, it is preferable that the compound shown by the said General formula (2) is a compound shown by following General formula (3).

X-R ⁴ -X (3)
(R ⁴ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms. X is a cyano group or an isocyanato group.)
In addition, the compound represented by the general formula (2) is 1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-.
Diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methyl = isocyanate), or bicyclo [2.2.1] heptane-2,6-diylbis (methyl = isocyanate), 2,4,4 -Trimethylhexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate are preferable.

Moreover, it is preferable to contain the said fluorine-containing ethylene carbonate derivative in 0.001 mass% or more and 10 mass% or less in nonaqueous electrolyte solution.
Moreover, it is preferable to contain 0.001 mass% or more and 10 mass% or less of the compound shown by the said General formula (2) in nonaqueous electrolyte solution.

  ADVANTAGE OF THE INVENTION According to this invention, regarding a lithium non-aqueous electrolyte secondary battery, a battery with a good balance of overall performance can be provided with respect to performance such as durability performance, capacity, resistance, and output characteristics.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is limited to these specific contents. However, various modifications can be made within the scope of the invention.

[1. Non-aqueous electrolyte]
The non-aqueous electrolyte solution of the first aspect of the present invention is a non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent.
(A) at least one compound selected from the group consisting of a carbonate having a carbon-carbon unsaturated bond and a compound represented by the following general formula (1);
(B) a fluorine-containing ethylene carbonate derivative;
(C) a compound represented by the following general formula (2),
It is characterized by containing.

(In the above formula (1), M is —O— or —NR ² —, and R ² is hydrogen or an optionally branched hydrocarbon group having 10 or less carbon atoms. R ¹ is a substituent. And a hydrocarbon group having 10 or less carbon atoms which may have a branched chain.)

(In the above formula (2), R ³ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms. W is a functional group having a molecular weight of 50 or less having a carbon-nitrogen multiple bond. n represents an integer of 1 to 4, and when n is an integer of 2 or more, the plurality of Ws may be the same functional group or different functional groups.
The non-aqueous electrolyte solution used in the non-aqueous electrolyte secondary battery of the second invention is the non-aqueous electrolyte solution of the first invention, wherein “(A) a carbonate having a carbon-carbon unsaturated bond, And at least one compound selected from the group consisting of compounds represented by the following general formula (1) "
Including the case of not including.

<1-0. Action>
Containing at least one compound selected from the group consisting of a carbonate having a carbon-carbon unsaturated bond and a compound represented by the general formula (1) according to the first aspect of the invention, and simultaneously containing a fluorine-containing ethylene carbonate derivative; By using a non-aqueous electrolyte containing a compound represented by the general formula (2) at the same time, the action / principle improves overall balance in terms of durability, capacity, resistance, output characteristics, etc. In the non-aqueous electrolyte secondary battery containing the lithium manganese composite oxide having a spinel structure in the positive electrode according to the second aspect of the present invention, the fluorine-containing ethylene carbonate derivative is contained, and at the same time, the general formula (2) By using a non-aqueous electrolyte containing a compound represented by the above, a comprehensive balance of durability performance and performance such as capacity, resistance, and output characteristics The action / principle to improve the efficiency is not clear, but it is considered as follows. However, the present invention is not limited to the operations and principles described below.

  Carbonate having carbon-carbon unsaturated bond, compound represented by general formula (1), fluorine-containing ethylene carbonate derivative and compound represented by general formula (2) all form a film-like structure on the negative electrode. It is thought that. A film formed of a carbonate having a carbon-carbon unsaturated bond and a compound represented by the general formula (1) is excellent in durability performance but very high in resistance. In the first aspect of the present invention, the composite film is formed by simultaneously adding the fluorine-containing ethylene carbonate derivative and the compound represented by the general formula (2), and the durability performance remains high while suppressing an increase in resistance. Can be kept in.

In addition, lithium manganese composite oxide having a spinel structure has relatively low resistance, but when used as a positive electrode active material for a non-aqueous electrolyte secondary battery, many manganese ions are eluted, and the eluted manganese ions reach the negative electrode. Then, the durability of the secondary battery is deteriorated by degrading the negative electrode. In 2nd this invention, it suppresses that a manganese ion accelerates | stimulates deterioration of a negative electrode by the composite film formed by adding simultaneously a fluorine-containing ethylene carbonate derivative and the compound shown by General formula (2). . At the same time, the compound represented by the general formula (2) has an effect of adsorbing on the surface of the lithium manganese composite oxide and suppressing the elution of manganese ions. Is considered to be improved comprehensively.

<1-1. Electrolyte>
The electrolyte used for the non-aqueous electrolyte solution of the present invention is not particularly limited, and can be arbitrarily adopted depending on the intended non-aqueous electrolyte secondary battery. In addition, when using the non-aqueous electrolyte of this invention for a non-aqueous electrolyte secondary battery, it is preferable to use lithium salt as electrolyte.
Specific examples of the electrolyte include inorganic lithium salts such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , Li ₂ CO ₃ , LiBF ₄ , and LiAlF ₄ ; LiCF ₃ SO ₃ , LiSO ₃ F, LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ ), LiN (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ ), LiN (CF ₃ SO ₂ ) _{2) (C 4 F 9 SO} 2), lithium cyclic 1,2-ethane sulfonyl imide, lithium cyclic 1,3-propanediol disulfonylimide, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1, 3-perfluoropropane disulfonylimide, lithium cyclic 1,4-perfluorobutane disulfonylimide, LiC (CF ₃ SO ₂ ) ₃ , 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 ), LiBF ₃ (C ₂ F ₅ ), LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) Fluorine-containing organic lithium salt such as ₂ ;

Lithium bis (oxalato) borate, lithium difluoro (oxalato) borate, lithium tris (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluoro (oxalato) phosphate, lithium bis (malonato) borate, lithium difluoro (malonato) borate , Lithium tris (malonate) phosphate, lithium difluorobis (malonate) phosphate, lithium tetrafluoro (malonate) phosphate, lithium bis (methylmalonate) borate, lithium difluoro (methylmalonate) borate, lithium tris (methylmalonate) phosphate, lithium difluorobis (methylmalonate) ) Phosphate, lithium tetrafluoro (methylmalonato) phosphate , Lithium bis (dimethylmalonate) borate, lithium difluoro (dimethylmalonate) borate, lithium tris (dimethylmalonate) phosphate, lithium difluorobis (dimethylmalonate) phosphate, lithium tetrafluoro (dimethylmalonate) phosphate, etc. Dicarboxylic acid complex lithium salt;
Sodium salts or potassium salts such as KPF ₆ , NaPF ₆ , NaBF ₄ , CF ₃ SO ₃ Na;
Etc.

Among these, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiSO ₃ F, LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonyl An imide is preferable, and LiPF ₆ , LiBF ₄ , LiSO ₃ F, or LiN (CF ₃ SO ₂ ) ₂ is particularly preferable. These electrolytes may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio. Among them, two types of combined use of inorganic lithium salt, combined use of inorganic lithium salt and fluorine-containing organic lithium salt, or combined use of inorganic lithium salt and lithium-containing dicarboxylic acid complex lithium salt are produced after gas generation during continuous charging or after high temperature storage. Deterioration is effectively suppressed, which is preferable.

In particular, the combination and the LiPF ₆ and LiBF _4, and an inorganic lithium salt such as _{LiPF 6, LiBF 4, LiCF 3} SO 3, LiSO 3 F, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2 ) Combination with a fluorine-containing organic lithium salt such as ₂ is preferred. When LiPF ₆ and LiBF ₄ are used in combination, the proportion of LiBF _{4 in} the entire electrolyte is preferably 0.001% by mass or more and 20% by mass or less. Within this range, the resistance of the non-aqueous electrolyte can be suppressed from increasing due to the low degree of dissociation of LiBF ₄ .

On the other hand, inorganic lithium salts such as LiPF ₆ and LiBF ₄ and fluorine-containing organic lithium salts such as LiCF ₃ SO ₃ , LiSO ₃ F, LiN (CF ₃ SO ₂ ) ₂ , and LiN (C ₂ F ₅ SO ₂ ) ₂ When using together, it is preferable that the ratio of the inorganic lithium salt to the whole electrolyte is 70 mass% or more and 99.9 mass% or less. Within this range, the ratio of the fluorine-containing organic lithium salt having a large molecular weight is generally too high compared to the inorganic lithium salt, and the ratio of the non-aqueous solvent in the entire non-aqueous electrolyte decreases, resulting in non-aqueous electrolysis. An increase in the resistance of the liquid can be suppressed.

  The concentration of the electrolyte such as a lithium salt in the final composition of the nonaqueous electrolytic solution of the present invention is arbitrary as long as the effects of the present invention are not significantly impaired, but preferably 0.5 mol / L or more, 3 mol / L or less. If the electrolyte concentration is above this lower limit, sufficient electric conductivity of the non-aqueous electrolyte solution can be easily obtained, and if it is lower than the upper limit, it is avoided that the viscosity is excessively increased, and good electric conductivity is obtained according to the present invention. It is easy to ensure the performance of the nonaqueous electrolyte secondary battery using the nonaqueous electrolyte solution. The concentration of the electrolyte such as a lithium salt is more preferably 0.6 mol / L or more, further preferably 0.8 mol / L or more, more preferably 2 mol / L or less, more preferably 1.5 mol / L. L or less.

In particular, when the non-aqueous solvent of the non-aqueous electrolyte is mainly a carbonate compound such as alkylene carbonate or dialkyl carbonate, LiPF ₆ may be used alone, but when used together with LiBF ₄ , capacity deterioration due to continuous charging is suppressed. Therefore, it is preferable. When these are used in combination, the amount of LiBF ₄ used relative to 1 mol of LiPF ₆ is preferably 0.005 mol or more and 0.4 mol or less. If it is less than this upper limit, it is easy to avoid the battery characteristics after high temperature storage from being lowered, and if it is more than the lower limit, gas generation and capacity deterioration during continuous charging are easily avoided. The amount of LiBF ₄ used is preferably 0.01 mol or more, particularly preferably 0.05 mol or more, and preferably 0.2 mol or less with respect to 1 mol of LiPF ₆ .

<1-2. Nonaqueous solvent>
The non-aqueous solvent contained in the non-aqueous electrolyte of the present invention is not particularly limited as long as it does not adversely affect the battery characteristics when it is used as a battery, but it is one or more of the non-aqueous solvents listed below. Preferably there is.
Examples of non-aqueous solvents include linear and cyclic carbonates, linear and cyclic carboxylic acid esters, linear and cyclic ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, and boron-containing organic solvents.

  The kind of the chain carbonate is not particularly limited, and examples thereof include dialkyl carbonates. Among them, the number of carbon atoms of the alkyl group is preferably 1 to 5, and particularly preferably 1 to 4. . Specific examples include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, di-n-propyl carbonate, and the like.

Among these, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate are preferable in terms of industrial availability and various characteristics in the non-aqueous electrolyte secondary battery.
Also, chain carbonates having fluorine atoms (hereinafter referred to as “fluorinated chain carbonate”)
Can also be used preferably. 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.

  The kind of cyclic carbonate is not particularly limited, and examples thereof include alkylene carbonate. Among them, the number of carbon atoms of the alkylene group constituting is preferably 2 to 6, particularly preferably 2 to 4. Specific examples include ethylene carbonate, propylene carbonate, butylene carbonate (2-ethylethylene carbonate, cis and trans 2,3-dimethylethylene carbonate) and the like.

Among these, ethylene carbonate or propylene carbonate is preferable in that various characteristics of the non-aqueous electrolyte non-aqueous electrolyte secondary battery are good.
The type of the chain carboxylic acid ester is not particularly limited. For example, methyl acetate, ethyl acetate, acetic acid-n-propyl, acetic acid-i-propyl, acetic acid-n-butyl, acetic acid-i-butyl, acetic acid-t-butyl , Methyl propionate, ethyl propionate, propionate-n-propyl, propionate-i-propyl, propionate-n-butyl, propionate-i-butyl, propionate-t-butyl, methyl butyrate, ethyl butyrate, etc. Is mentioned.

Among these, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and ethyl butyrate are preferable in terms of industrial availability and various characteristics in non-aqueous electrolyte secondary batteries.
Furthermore, it does not specifically limit about cyclic carboxylic acid ester, For example, (gamma) -butyrolactone, (gamma) -valerolactone, (delta) -valerolactone etc. are mentioned.

Among these, γ-butyrolactone is preferable in terms of industrial availability and various characteristics in the non-aqueous electrolyte secondary battery.
The type of chain ether is not particularly limited, and examples thereof include dimethoxymethane, dimethoxyethane, diethoxymethane, diethoxyethane, ethoxymethoxymethane, and ethoxymethoxyethane.

Of these, dimethoxyethane and diethoxyethane are preferable in terms of industrial availability and various characteristics in the non-aqueous electrolyte secondary battery.
The cyclic ether is not particularly limited, and examples thereof include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran and the like.
Further, the organic solvent containing phosphorus is not particularly limited. For example, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, trimethylphosphine oxide, triethylphosphine Examples thereof include oxide and triphenylphosphine oxide.

The kind of the sulfur-containing organic solvent is not particularly limited, and examples thereof include ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, ethyl methyl sulfone, Examples thereof include diphenyl sulfone, methyl phenyl sulfone, dibutyl disulfide, dicyclohexyl disulfide, tetramethyl thiuram monosulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide and the like.
The type of the boron-containing organic solvent is not particularly limited, and examples thereof include boroxines such as 2,4,6-trimethylboroxine and 2,4,6-triethylboroxine.

Among these non-aqueous solvents, linear and cyclic carbonates or linear and cyclic carboxylic acid esters are preferable in terms of various characteristics in non-aqueous electrolyte non-aqueous electrolyte secondary batteries, and among these, ethylene Carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, trifluoromethyl methyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, butyric acid Methyl, ethyl butyrate, and γ-butyrolactone are more preferable. Ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, trifluoromethyl methyl carbonate, bis (2 2,2-trifluoroethyl) carbonate, methyl acetate, ethyl acetate, methyl propionate, and ethyl butyrate more preferred.
These nonaqueous solvents may be used alone or in combination of two or more, but two or more of them are preferably used. For example, it is preferable to use a high dielectric constant solvent of cyclic carbonates in combination with a low viscosity solvent such as chain carbonates or chain esters.

  Examples of preferred combinations of cyclic carbonates and chain carbonates include combinations of ethylene carbonate and chain carbonates, such as ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, Examples thereof include ethylene carbonate, dimethyl carbonate and diethyl carbonate, ethylene carbonate, dimethyl carbonate and ethyl 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 carbonate and chain carbonate is also preferable. When propylene carbonate is contained, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, particularly preferably 95: 5 to 50:50. Furthermore, when the amount of propylene carbonate in the entire non-aqueous solvent is 0.1% by volume or more and 10% by volume or less, further excellent discharge is maintained while maintaining the characteristics of the combination of ethylene carbonate and chain carbonates. This is preferable because load characteristics can be obtained. The amount of propylene carbonate in the entire non-aqueous solvent is more preferably 1% by volume, particularly preferably 2% by volume or more, more preferably 8% by volume or less, and particularly preferably 5% by volume or less.

  Among these, those containing asymmetrical chain carbonates as chain carbonates are more preferable, and in particular, ethylene carbonate and dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate and diethyl carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate. Among them, those containing diethyl carbonate and ethyl methyl carbonate, or further containing propylene carbonate are preferable because the balance between cycle characteristics and discharge load characteristics is good. In particular, it is preferable that the asymmetric chain carbonate is ethyl methyl carbonate, and it is preferable that the alkyl group constituting the dialkyl carbonate has 1 to 2 carbon atoms.

  Other examples of preferred non-aqueous solvents are those containing chain carboxylic esters. In particular, those containing a chain carboxylic acid ester in the mixed solvent of cyclic carbonates and chain carbonates are preferable from the viewpoint of improving the discharge load characteristics of the battery. In this case, as the chain carboxylic acid esters, Are particularly preferably methyl acetate, ethyl acetate, methyl propionate, methyl butyrate and ethyl butyrate. The volume of the chain carboxylic acid esters in the non-aqueous solvent is preferably 5% by volume or more, more preferably 8% by volume or more, particularly preferably 10% by volume or more, preferably 50% by volume or less, more preferably It is 35% by volume or less, particularly preferably 30% by volume or less, and particularly preferably 25% by volume or less.

<1-3. Carbonate having carbon-carbon unsaturated bond and compound represented by the following general formula (1)>
The non-aqueous electrolyte solution of the first aspect of the present invention comprises a carbonate having a carbon-carbon unsaturated bond (hereinafter sometimes abbreviated as “unsaturated carbonate”) and a compound represented by the following general formula (1) ( Hereinafter, at least one compound selected from the group consisting of “sometimes referred to as“ specific cyclic compound ”) is contained as an essential component. Moreover, you may make the said compound contain in the non-aqueous electrolyte solution used with the non-aqueous electrolyte secondary battery of 2nd this invention. In these non-aqueous electrolyte solutions of the present invention, one kind of compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” may be used, or any combination of these two or more kinds may be used.

(In the above formula (1), M is —O— or —NR ² —, and R ² is hydrogen or an optionally branched hydrocarbon group having 10 or less carbon atoms. R ¹ is a substituent. And a hydrocarbon group having 10 or less carbon atoms which may have a branched chain.)
In addition, regarding “unsaturated carbonate” and “specific cyclic compound”, commercially available products may be used, respectively, and the production method is not particularly limited, and a known method is arbitrarily selected. Can be manufactured.

The content in the electrolyte of at least one compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” in the non-aqueous electrolyte is arbitrary as long as the effects of the present invention are not significantly impaired. However, the total amount thereof is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass, based on the total amount of the non-aqueous electrolyte. It is at least mass%. In addition, the upper limit is a sum of them, usually 10% by mass or less, preferably 8% by mass or less, more preferably 6% by mass or less, further preferably 5% by mass or less, particularly preferably 4% by mass or less, and most preferably 3%. It is below mass%. When the concentration of at least one compound selected from the group consisting of "unsaturated carbonate" and "specific cyclic compound" is within the above range, the action at the electrode interface proceeds more favorably, resulting in a decrease in battery capacity. Can be effectively prevented.

  When at least one compound selected from the group consisting of "unsaturated carbonate" and "specific cyclic compound" is contained in a non-aqueous electrolyte solution and actually used for the production of a non-aqueous electrolyte secondary battery, Even when disassembled and the non-aqueous electrolyte is extracted again, the content of the non-aqueous electrolyte is often significantly reduced. Therefore, what can detect "unsaturated carbonate" and "specific cyclic compound" in a small amount from the non-aqueous electrolyte extracted from the battery is considered to be included in the present invention. In addition, when at least one compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” is actually used as a non-aqueous electrolyte solution for producing a non-aqueous electrolyte secondary battery, Even if the non-aqueous electrolyte solution disassembled and extracted again does not contain “unsaturated carbonate” and “specific cyclic compound”, it is another component of the non-aqueous electrolyte secondary battery. It is often detected on the positive electrode, negative electrode or separator. Therefore, when at least one compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” is detected from at least one constituent member of the positive electrode, the negative electrode, and the separator is also considered to be included in the present invention. It is.

  Furthermore, at least one compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” is contained in advance in the separator of the non-aqueous electrolyte secondary battery to be produced or on the surface of the separator. Also good. In this case, a part or all of at least one compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” contained in advance is dissolved in the non-aqueous electrolyte solution and exhibits its function. Is expected and included in the present invention. The means to be contained in the separator or on the surface of the separator in advance is not particularly limited, but specific examples include at least one selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” at the time of separator production. In the separator before the non-aqueous electrolyte secondary battery is prepared, at least one compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound” is arbitrarily added. Examples include a method in which a solution prepared by dissolving in a non-aqueous solvent in advance is applied or impregnated, and then the solvent used is dried and removed.

<1-3-1. Unsaturated carbonate>
The “unsaturated carbonate” in the first invention is not particularly limited, and any one may be used. The molecular weight is not particularly limited and may be arbitrary as long as the effects of the present invention are not significantly impaired. Usually, 50 or more, preferably 70 or more, more preferably 75 or more, particularly preferably 80 or more, and usually 250 or less, Preferably it is 200 or less, more preferably 150 or less, and particularly preferably 120 or less. When the molecular weight is within the above range, the solubility in the non-aqueous electrolyte solution is excellent, and a more excellent effect is easily achieved.

The “unsaturated carbonate” is not particularly limited as long as it is a carbon-carbon “unsaturated carbonate” such as a carbon-carbon double bond or a carbon-carbon triple bond, and any “unsaturated carbonate” may be used. it can. Carbonate having an aromatic ring is also included in “unsaturated carbonate”.
Examples of “unsaturated carbonates” include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond, phenyl carbonates, vinyl carbonates, allyl carbonates, propargyl carbonates Etc.

Specific examples of vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, catechol carbonate and the like.
Specific examples of ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon unsaturated bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, ethynyl ethylene carbonate, propargyl ethylene carbonate, phenyl ethylene carbonate, Examples include 4,5-diphenylethylene carbonate.

Specific examples of phenyl carbonates include diphenyl carbonate, ethyl phenyl carbonate, methyl phenyl carbonate, t-butyl phenyl carbonate, and the like.
Specific examples of vinyl carbonates include divinyl carbonate and methyl vinyl carbonate.

Specific examples of allyl carbonates include diallyl carbonate and allyl methyl carbonate.
Specific examples of propargyl carbonates include dipropargyl carbonate and propargyl methyl carbonate.
Among these, vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond are preferable, and in particular, vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate have a stable interface protective film. It can be formed and used more preferably.

<1-3-2. Specific cyclic compound>
There is no particular limitation on the molecular weight of the compound represented by the following general formula (1) in the first present invention (“specific cyclic compound”), and it is optional as long as the effects of the present invention are not significantly impaired. Is practically 90 or more, more preferably 95 or more, and usually 300 or less, preferably 250 or less, more preferably 230 or less. When the molecular weight is within the above range, the solubility in the non-aqueous electrolyte solution is excellent, and it becomes easier to achieve more effective effects.

In formula (1), M is —O— or —NR ² —, and R ² is hydrogen or a hydrocarbon group having 10 or less carbon atoms which may be branched. R ² is preferably hydrogen or a hydrocarbon group having 6 or less carbon atoms, more preferably hydrogen, an alkyl group having 1 to 5 carbon atoms, or a phenyl group, and more preferably hydrogen or a methyl group. Is particularly preferred. R ¹ is an optionally branched hydrocarbon group having 10 or less carbon atoms, preferably a hydrocarbon group having 6 or less carbon atoms, and among them, —CH ₂ —CH ₂ —, —CH ₂ —CH _{2 -CH 2 -, - CH =} CH -, - CH = C (CH 3) -, - CH 2 -C (= CH 2) - and selected from the group consisting of hydrocarbon radicals represented by the following structural formula (4) It is more preferable to represent a hydrocarbon group.

  Specific examples of the “specific cyclic compound” include malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, phthalic anhydride, cyclohexane 1,2-dicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2 · BR> C3-dicarboxylic anhydride , Methyl-5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, malonimide, succinimide, glutarimide, maleimide, phthalimide, N-methylsuccinimide, N-methyl Glutarimide, N-methylmaleimide, N-methylphthalimide, N-ethylsuccini N-ethylglutarimide, N-ethylmaleimide, N-ethylphthalimide, N-phenylsuccinimide, N-phenylglutarimide, N-phenylmaleimide, N-phenylphthalimide, N-benzylsuccinimide, N-benzylglutar Imide, N-benzylmaleimide, N-benzylphthalimide, N-cyclohexylsuccinimide, N-cyclohexylglutarimide, N-cyclohexylmaleimide, N-cyclohexylphthalimide, tetrahydrophthalimide, 2-methylsuccinimide, 2-methylsuccinimide, 2 -Ethyl maleimide, ethosuximide, 3,3-tetramethylene glutarimide, 3,3-dimethyl glutarimide and the like.

  Among these, succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, itaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, succinimide, glutarimide, maleimide, phthalimide, N-methyl succinimide, N-methyl glutarimide, N-methyl maleimide, N-methyl phthalimide, N-ethyl succinimide, N-ethyl glutarimide, N-ethyl maleimide, N-ethyl phthalimide, N-phenyl succinimide, N-phenylglutarimide, N-phenylmaleimide, N-phenylphthalimide are preferred,

Succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, itaconic anhydride, phthalic anhydride, succinimide, glutarimide, maleimide, phthalimide, N-methylsuccinimide, N-methylglutarimide, N-methylmaleimide, N-methylphthalimide is more preferred,
Most preferred is succinic anhydride or maleic anhydride.
The reason why the above compound is preferable includes that the production cost of the electrolytic solution can be suppressed due to industrial availability, and that the “specific cyclic compound” is easily dissolved in the non-aqueous electrolytic solution.

<1-4. Fluorine-containing ethylene carbonate derivative>
The non-aqueous electrolyte solution used in the non-aqueous electrolyte solution of the first invention and the non-aqueous electrolyte secondary battery of the second invention contains a fluorine-containing ethylene carbonate derivative as an essential component. In the non-aqueous electrolyte solution of the present invention, one type of compound selected from fluorine-containing ethylene carbonate derivatives may be used, or two or more types may be used in combination.

The fluorine-containing ethylene carbonate derivative in the present invention is not particularly limited, and any one may be used. The molecular weight is not particularly limited and may be arbitrary as long as the effects of the present invention are not significantly impaired. However, it is usually 500 or less, preferably 300 or less, more preferably 200 or less, and particularly preferably 150 or less. When the molecular weight is within the above range, the solubility in the non-aqueous electrolyte solution is excellent, and a more excellent effect is easily achieved.
Preferable examples of the fluorine-containing ethylene carbonate derivative include the following.

Among them, 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one is particularly preferable, has a small molecular weight, and has excellent solubility in a non-aqueous electrolyte solution. It is excellent in that it is easily available and inexpensive. As 4,5-difluoro-1,3-dioxolan-2-one, a trans isomer is preferable to a cis isomer.
In addition, regarding the fluorine-containing ethylene carbonate derivative, commercially available products may be used, respectively, and when manufacturing, there is no particular limitation on the manufacturing method, and any known method can be selected and manufactured. is there.

Further, the fluorine-containing ethylene carbonate derivative is a compound that is suitable as a non-aqueous solvent and as an auxiliary agent, but it is called so for convenience depending on the content in the non-aqueous electrolyte.
The content of the fluorine-containing ethylene carbonate derivative in the non-aqueous electrolyte when the fluorine-containing ethylene carbonate derivative is used as a non-aqueous solvent is arbitrary as long as the effects of the present invention are not significantly impaired, but with respect to the entire non-aqueous electrolyte. The total amount thereof is usually 3% by volume or more, preferably 5% by volume or more, more preferably 10% by volume or more, particularly preferably 15% by volume or more, and the total thereof is usually 40% by volume or less, preferably Is 30% by volume or less, more preferably 25% by volume or less. Within this range, the oxidation resistance of the fluorine-containing ethylene carbonate derivative is sufficiently exhibited, and the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristic improving effect.

  Further, the content of the fluorine-containing ethylene carbonate derivative in the non-aqueous electrolyte when the fluorine-containing ethylene carbonate derivative is used as an auxiliary agent is arbitrary as long as the effects of the present invention are not significantly impaired, but the entire non-aqueous electrolyte is used. On the other hand, the total amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more. In addition, the upper limit is a sum of them, usually 10% by mass or less, preferably 8% by mass or less, more preferably 6% by mass or less, further preferably 5% by mass or less, particularly preferably 4% by mass or less, and most preferably 3%. It is below mass%. When the concentration of the fluorine-containing ethylene carbonate derivative is within the above range, most of the fluorine-containing ethylene carbonate is consumed for the reaction at the electrode interface, so the amount of gas generation increases and the discharge capacity maintenance rate decreases. Easy to avoid.

When the fluorine-containing ethylene carbonate derivative is contained in a non-aqueous electrolyte solution and actually used for the production of a non-aqueous electrolyte secondary battery, even if the battery is disassembled and the non-aqueous electrolyte solution is extracted again, Is often significantly reduced. Accordingly, it is considered that the present invention includes a non-aqueous electrolyte extracted from a battery that can detect even a small amount of a fluorine-containing ethylene carbonate derivative. In addition, when the fluorine-containing ethylene carbonate derivative is actually used as a non-aqueous electrolyte for the production of a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte obtained by disassembling the battery and extracting it again contains a fluorine-containing ethylene carbonate derivative. Even when it is not contained, it is often detected on the positive electrode, the negative electrode, or the separator, which is another component of the non-aqueous electrolyte secondary battery. Accordingly, the present invention also includes a case where a fluorine-containing ethylene carbonate derivative is detected from at least one constituent member of the positive electrode, the negative electrode, and the separator.

  Furthermore, the fluorine-containing ethylene carbonate derivative may be previously contained in the separator of the non-aqueous electrolyte secondary battery to be produced or on the surface of the separator. In this case, a part or all of the fluorine-containing ethylene carbonate derivative contained in advance is expected to be dissolved in the non-aqueous electrolyte solution and exhibit its function, and is considered to be included in the present invention. There is no particular limitation on the means for pre-contained in the separator or on the surface of the separator, but as a specific example, a fluorine-containing ethylene carbonate derivative is mixed at the time of producing the separator, or a non-aqueous electrolyte secondary battery is produced. For example, a separator prepared by dissolving a fluorine-containing ethylene carbonate derivative in an arbitrary non-aqueous solvent in advance or applying or impregnating the separator before drying is used to dry and remove the solvent. It is done.

<1-5. Compound represented by the following general formula (2)>
The non-aqueous electrolyte used in the non-aqueous electrolyte of the first invention and the non-aqueous electrolyte secondary battery of the second invention is a compound represented by the following general formula (2) (hereinafter referred to as “specific CN”). It may be referred to as a “compound”) as an essential component. In the non-aqueous electrolyte solution of the present invention, one type of compound selected from the specific CN compounds may be used, or two or more types may be used in combination.

In Formula (2), R ³ is a hydrocarbon group that may have a hetero element having 15 or less carbon atoms. W is a functional group having a molecular weight of 50 or less having a carbon-nitrogen multiple bond. n represents an integer of 1 to 4, and when n is an integer of 2 or more, the plurality of Ws may be the same functional group or different functional groups.

The molecular weight of the “specific CN compound” in the present invention is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. Usually, 50 or more, preferably 70 or more, more preferably 75 or more, and usually 500 or less. Preferably, 400 or less, more preferably 300 or less, particularly preferably 270 or less is practical. When the molecular weight is within the above range, the solubility in the non-aqueous electrolyte solution is excellent, and a more excellent effect is easily achieved.
The “specific CN compound” is preferably a compound represented by the following general formula (3). The compound represented by the following general formula (3) is particularly preferable among “specific CN compounds” from the viewpoints of solubility in a non-aqueous electrolyte, stability in a non-aqueous electrolyte, and the like.

X-R ⁴ -X (3)
In Formula (3), R ⁴ is a hydrocarbon group that may have a heteroelement having 15 or less carbon atoms, and X is a cyano group or an isocyanato group. Specific examples of R ⁴ include alkylene groups or derivatives thereof, alkenylene groups or derivatives thereof, cycloalkylene groups or derivatives thereof, alkynylene groups or derivatives thereof, cycloalkenylene groups or derivatives thereof, arylene groups or derivatives thereof, carbonyl groups or derivatives thereof Derivatives, sulfonyl groups or derivatives thereof, sulfinyl groups or derivatives thereof, phosphonyl groups or derivatives thereof, phosphinyl groups or derivatives thereof, amide groups or derivatives thereof, imide groups or derivatives thereof, ether groups or derivatives thereof, thioether groups or derivatives thereof, It is preferably a borinic acid group or a derivative thereof, a borane group or a derivative thereof, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, Rene group or a derivative thereof, and arylene group or a derivative thereof are more preferable.

  Preferable specific examples of the “specific CN compound” include propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, capronitrile, isocapronitrile, heptanenitrile, octanenitrile, nonanenitrile, malononitrile, succino Nitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2 -Dimethyl succinonitrile, 2,3-dimethyl succinonitrile, 2,3,3-trimethyl succinonitrile, 2,2,3,3-tetramethyl succin Nitrile, 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-teto Methylglutaronitrile, 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, 3,3 ′-(ethylenedithio) dipropionitrile, 1,2,3-propanetri Carbonitrile, 1,3,5-heptanetricarbonitrile, 1,2,3-tris (2-cyanoethoxy) propane, tris (2-cyanoethyl) amine, 1,3,5-cyclohexanetricarbonitrile, 7, 7,8,8-tetracyanoquinodimethane, 2,5-dimethyl-7,7,7,8-tetracyanoquinodimeta , Cyano compounds such as 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane,

1-isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1- Isocyanatodecane, 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 1,8-diisocyanatooctane, 1 , 9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4 -Diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyana 2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-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- Diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1′-diisocyanate, dicyclohexylmethane-2,2′-diisocyanate, dicyclohexylmethane-3,3 '-Diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-triisocyanate Methylbenzene, bicyclo [2.2.1] heptane-2,5-diylbis (methyl = isocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methyl = isocyanate), 1,3,5 -Tris (6-isocyanatohex-1-yl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4- (isocyanatomethyl) octane Isocyanato compounds such as methylene = diisocyanate.

  Among them, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinol Sinonitrile, 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, bicyclohexene Sil-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3-dimethylsuccinonitrile, 2,2-diisobutyl-3,3- Dimethyl succinonitrile, 2-methyl glutaronitrile, 2,3-dimethyl glutaronitrile, 2,4-dimethyl glutaronitrile, 2,2,3,3-tetramethyl glutaronitrile, 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-dicyanobenzene, 1, - dicyanobenzene, 1,4-dicyanobenzene, 3,3 '- (ethylenedioxy) dipropionate nitrile, 3,3' - dinitriles such as (ethylene dithio) dipropionate nitrile,

1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 1,8-diisocyanatooctane, 1,9-di Isocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2 , 3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6 -Diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, key Diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanato Cyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1′-diisocyanate, dicyclohexylmethane-2,2′-diisocyanate, dicyclohexylmethane-3,3′-diisocyanate, Dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methyl = isocyanate), bicyclo [2.2.1] heptane-2,6-diylbis Diisocyanates such as (methyl = isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate are more preferable.

Of these, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimeonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, fumaronitrile, 1,6-diisocyanatohexane, 1,3-bis ( Isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,
4′-diisocyanate, bicyclo [2.2.1] heptane-2,5-diylbis (methyl = isocyanate), bicyclo [2.2.1] heptane-2,6-diylbis (methyl = isocyanate), 2,4 , 4-trimethylhexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate are particularly preferred from the viewpoints of solubility in the electrolyte and cost.

Of the “specific CN compounds”, isocyanato compounds are preferred. This is because the reactivity is optimal and contributes more favorably to the formation of the coating film required in the present invention.
Usually, in the “specific CN compound”, the smaller the molecular weight, the larger the proportion of nitrile groups or isocyanato groups in one molecule and the higher the viscosity of the molecule, while the higher the molecular weight, the higher the boiling point of the compound. Therefore, from the viewpoint of improving work efficiency, succinonitrile, glutaronitrile, adiponitrile, pimeonitrile, suberonitrile, 1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4 4,4'-diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate are very preferred. In addition, as the “specific CN compound”, a commercially available product may be used, and in the case of production, the production method is not limited, and those produced by a known method can be used.

<1-6. Additives>
The nonaqueous electrolytic solution of the present invention may contain various additives as long as the effects of the present invention are not significantly impaired. A conventionally well-known thing can be arbitrarily used for an additive. An additive may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Examples of the additive include an overcharge inhibitor and an auxiliary agent for improving capacity maintenance characteristics and cycle characteristics after high-temperature storage.

<1-6-1. Overcharge prevention agent>
Specific examples of the overcharge inhibitor include toluene derivatives such as toluene and xylene;
Biphenyl derivatives unsubstituted or substituted with an alkyl group, such as biphenyl, 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl;
o-terphenyl, m-terphenyl, p-terphenyl and the like terphenyl derivatives unsubstituted or substituted with an alkyl group;
Partial hydrides of terphenyl derivatives unsubstituted or substituted with alkyl groups;
Cycloalkylbenzene derivatives such as cyclopentylbenzene and cyclohexylbenzene;
Alkylbenzene derivatives having a tertiary carbon directly bonded to a benzene ring such as cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene;
alkylbenzene derivatives having a quaternary carbon directly bonded to a benzene ring, such as t-butylbenzene, t-amylbenzene, t-hexylbenzene;
Aromatic compounds having an oxygen atom such as diphenyl ether and dibenzofuran;
Aromatic compounds such as

Furthermore, specific examples of other overcharge preventing agents include partially fluorinated products of the aromatic compounds such as fluorobenzene, fluorotoluene, benzotrifluoride, 2-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene and the like. ;
Fluorine-containing anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 1,6-difluoroanisole;
And so on.

In addition, these overcharge inhibitors may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations. Moreover, when using together by arbitrary combinations, it may use together by the compound of the same classification illustrated above and may be used together by a compound of a different classification | category.
When blending the overcharge inhibitor, the blending amount of the overcharge inhibitor is arbitrary as long as the effect of the present invention is not significantly impaired, but is preferably 0.001% by mass or more based on the whole non-aqueous electrolyte. It is the range of 10 mass% or less.

  If the non-aqueous electrolyte of the present invention contains an overcharge inhibitor within a range that does not significantly impair the effects of the present invention, the overcharge protection circuit such as an incorrect usage or an abnormality of the charging device should operate normally. Even if the battery is overcharged due to the situation, it is preferable because the safety of the non-aqueous electrolyte secondary battery is improved.

<1-6-2. Auxiliary>
On the other hand, specific examples of the auxiliary for improving capacity maintenance characteristics and cycle characteristics after high-temperature storage include the following.
Carbonate compounds other than those corresponding to carbonates having an unsaturated bond such as erythritan carbonate and spiro-bis-dimethylene carbonate;
Cyclic sulfites such as ethylene sulfite;
Cyclic sulfonate esters such as 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone;
Chain sulfonate esters such as methyl methanesulfonate and busulfan;
Cyclic sulfones such as sulfolane and sulfolene;

Chain sulfones such as dimethyl sulfone, diphenyl sulfone, and methylphenyl sulfone;
Sulfides such as dibutyl disulfide, dicyclohexyl disulfide, tetramethylthiuram monosulfide;
Sulfur-containing compounds such as sulfonamides such as N, N-dimethylmethanesulfonamide and N, N-diethylmethanesulfonamide;
Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone;
Hydrocarbon compounds such as heptane, octane, cycloheptane;
Fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, and benzotrifluoride;
Etc.

In addition, these adjuvants may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
When the non-aqueous electrolyte solution of the present invention contains these auxiliaries, it is optional as long as the effects of the present invention are not significantly impaired, but preferably 0.001% by mass or more, based on the whole non-aqueous electrolyte solution. It is the range of the mass% or less.

<1-7. Method for producing non-aqueous electrolyte>
The non-aqueous electrolyte solution of the first aspect of the present invention includes an electrolyte, at least one compound selected from the group consisting of an “unsaturated carbonate” and a “specific cyclic compound”, and fluorine-containing ethylene. It can be prepared by dissolving the carbonate derivative, the “specific CN compound”, and the above-mentioned “additives” and “auxiliaries” as necessary.

The non-aqueous electrolyte solution of the second aspect of the present invention includes an electrolyte, a fluorine-containing ethylene carbonate derivative, a “specific CN compound”, an “unsaturated carbonate”, and a “specific” as necessary. It can be prepared by dissolving at least one compound selected from the group consisting of “cyclic compounds” and the aforementioned “additives” and “auxiliaries”.
In preparing the non-aqueous electrolyte, each raw material of the non-aqueous electrolyte, that is, at least one compound selected from the group consisting of electrolytes such as lithium salts, “unsaturated carbonates”, and “specific cyclic compounds”, The fluorine-containing ethylene carbonate derivative, “specific CN compound”, non-aqueous solvent, additive, auxiliary agent and the like are preferably dehydrated in advance. The degree of dehydration is usually 50 ppm or less, preferably 30 ppm or less.

  By removing moisture in the non-aqueous electrolyte, water electrolysis, water-lithium metal reaction, lithium salt hydrolysis, and the like are less likely to occur. The dehydration means is not particularly limited. For example, when the object to be dehydrated is a liquid such as a non-aqueous solvent, a desiccant such as molecular sieve may be used. In addition, when the object to be dehydrated is a solid such as an electrolyte, it may be dried by heating at a temperature lower than the temperature at which decomposition occurs.

[2. Non-aqueous electrolyte secondary battery]
The non-aqueous electrolyte secondary battery of the present invention comprises a negative electrode and a positive electrode capable of inserting and extracting lithium ions and the non-aqueous electrolyte of the present invention.
<2-1. Battery configuration>
The non-aqueous electrolyte secondary battery of the first aspect of the present invention is the same as the conventionally known non-aqueous electrolyte non-aqueous electrolyte secondary battery except for the non-aqueous electrolyte described above. The positive electrode and the negative electrode are laminated through a porous membrane (separator) impregnated with the nonaqueous electrolyte solution of the invention, and these are housed in a case (exterior body). Therefore, the shape of the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

  The non-aqueous electrolyte secondary battery of the second aspect of the present invention will be described later in <2-3. The structure other than the specific positive electrode described in detail in the section of “Positive electrode> and the non-aqueous electrolyte described above is the same as that of a conventionally known non-aqueous electrolyte non-aqueous electrolyte secondary battery. The positive electrode and the negative electrode are laminated through a porous membrane (separator) impregnated with the nonaqueous electrolyte solution of the invention, and these are housed in a case (exterior body). Therefore, the shape of the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

<2-2. Non-aqueous electrolyte>
As the non-aqueous electrolyte, the above-described non-aqueous electrolyte of the present invention is used. In addition, in the range which does not deviate from the meaning of this invention, it is also possible to mix and use other nonaqueous electrolyte solution with respect to the nonaqueous electrolyte solution of this invention.
<2-3. Positive electrode>
The positive electrode used for the non-aqueous electrolyte secondary battery of the present invention will be described below.

<2-3-1. Cathode active material>
The positive electrode active material used for the positive electrode will be described below.
(1) Composition The positive electrode of the second aspect of the present invention is characterized by containing a lithium manganese composite oxide having a spinel structure. Such a lithium manganese composite oxide is preferably one in which a part of the manganese site is substituted. In particular, those substituted with typical elements are preferred. Typical elements that replace such manganese sites include Li and B.
, Na, Mg, Al, Ca, Zn, Ga, Ge and the like. Of course, it is possible to replace the manganese site with a plurality of elements. Li, Mg, Al, and Ga are preferred as manganese site substitution elements, and Al and / or Li are particularly preferred. The substitution amount of the typical element is preferably 0.03 mol or more in 2 mol of manganese, more preferably 0.05 mol or more, and most preferably 0.07 mol or more.
Particularly preferred lithium manganese composite oxides have the general formula

Li _{1 + w} [Mn _(2-x) Al _y Li _z ] O ₄
(Wherein w, x, y and z are each a number of 0 or more and x = y + z, where y and z are not 0 at the same time). Here, w is usually 0.3 or less, preferably 0.2 or less, particularly preferably 0.15 or less. y is usually 0.5 or less, preferably 0.25 or less, and usually 0.1 or more. Z is usually 0.1 or less, preferably 0.08 or less. If y and z are too small, the high temperature characteristics may be deteriorated. On the other hand, if y and z are too large, the capacity tends to decrease.

In the above, the oxygen atom of the composite oxide may have nonstoichiometry, and a part of the oxygen atom may be substituted with a halogen element such as fluorine.
The positive electrode of the second aspect of the present invention preferably contains a lithium manganese composite oxide having a spinel structure, and further contains a lithium nickel composite oxide having a layered structure. This is because the cycle characteristics and storage characteristics can be improved in a high temperature atmosphere.

  The mixing ratio of the lithium manganese composite oxide having a spinel structure and the lithium nickel composite oxide having a layered structure is usually in the range of 20: 1 to 1:20, preferably 15: 1, by weight. It is in the range of 1:15, more preferably in the range of 10: 1 to 1:10, particularly preferably in the range of 5: 1 to 1: 5, most preferably in the range of 5: 1 to 1: 1. If it deviates from this range, the effects of the present invention may be difficult to obtain.

Such a lithium nickel composite oxide is preferably one in which a part of the nickel site is substituted. Preferable elements for the substitution element include metal elements such as Al, Fe, Sn, Cr, Cu, Ti, Zn, Co, and Mn. Of course, it is also possible to replace nickel sites with a plurality of elements. In particular, it is preferably substituted with Al and / or Co and / or Mn.
Particularly preferred lithium nickel composite oxides have the general formula

_{Li 1 + s [Ni (1} -p) Co q M r] O 2
(Wherein M represents Al or Mn. P, q, r and s are each a number of 0 or more, and p = q + r, where q and r are not 0 at the same time) It is. Here, q and r are each independently usually 0.7 or less, preferably 0.5 or less, and usually 0.05 or more, preferably 0.1 or more. When M is Al, r is usually 0.1 or less, preferably 0.08 or less, and usually 0.02 or more. s is usually 0.3 or less, preferably 0.2 or less, particularly preferably 0.15 or less. If q or r is too small, the high temperature characteristics tend to be poor, while if too large, the capacity tends to decrease.

In the above, the oxygen atom of the lithium nickel composite oxide may have nonstoichiometry, and a part of the oxygen element may be substituted with a halogen element such as fluorine.
The positive electrode of the second present invention may further contain another active material.
In the first aspect of the present invention, the above active material may be used, but other active materials may be used and are not particularly limited. The other 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, lithium-containing transition metal phosphate compounds, lithium-containing transition metal silicate compounds, and lithium-containing transition metal borate compounds.

As the transition metal of the lithium transition metal composite oxide, there are some overlaps with the above, but V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable, and specific examples include lithium, such as LiCoO _2. Cobalt composite oxides, lithium nickel composite oxides such as LiNiO ₂ , lithium manganese composite oxides such as LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO _4, transition metal atoms that are the main components of these lithium transition metal composite oxides Part of is replaced with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W Etc.

As specific examples of the substituted ones, 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 , 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, Si, Nb, Mo, Sn, W and the like substituted with other metals.

The transition metal of the lithium-containing transition metal borate compound, V, Ti, Cr, Mn , Fe, Co, Ni, Cu and the like are preferable, and specific examples, LiFeBO ₃ like boric Santetsurui, LiCoBO ₃ Cobalt borates such as these, some of the transition metal atoms that are the main components of these lithium transition metal borate compounds are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Examples include those substituted with other metals such as Ga, Zr, Si, Nb, Mo, Sn, and W.

(2) Surface coating A material having a composition different from that of the main constituent of the positive electrode active material (hereinafter referred to as “surface adhering substance” as appropriate) may be used on the surface of the positive electrode active material. . Examples of 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, Examples thereof include sulfates such as calcium sulfate and aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate, and carbon.

  These surface adhering substances are, for example, a method in which they are dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, and then dried. Then, 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 attaching carbon, the method of attaching carbonaceous material mechanically later, for example in the form of activated carbon etc. can also be used.

The mass of the surface adhering substance adhering to the surface of the positive electrode active material is preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more with respect to the mass of the positive electrode active material. Further, it is preferably 20% or less, more preferably 10% or less, still more preferably 5% or less.
The surface adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte on the surface of the positive electrode active material, and can improve the battery life. Moreover, when the adhesion amount is within the above range, the effect can be sufficiently exhibited, and resistance is hardly increased without inhibiting the entry and exit of lithium ions.

(3) Shape As the shape of the positive electrode active material particles, a lump shape, a polyhedron shape, a spherical shape, an elliptical spherical shape, a plate shape, a needle shape, a columnar shape, and the like, which are conventionally used, are used. The primary particles may be aggregated to form secondary particles, and the shape of the secondary particles may be spherical or elliptical.

(4) Tap Density Tap density positive electrode active material, preferably at 0.5 g · ^{cm -3} or more, more preferably 1.0 g · ^{cm -3} or more, 1.5 g · ^{cm -3} or more is more preferable. Further, it is preferably 4.0 g · cm ⁻³ or less, and more preferably 3.7 g · cm ⁻³ or less. By using a metal composite oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. When the tap density of the positive electrode active material is within the above range, the amount of the dispersion medium necessary for forming the positive electrode active material layer becomes appropriate, and the amount of the conductive material and binder is also appropriate. The positive electrode active material filling rate is not limited, and the battery capacity is less affected.

The tap density of the positive electrode active material is measured by passing a sieve having a mesh size of 300 μm, dropping the sample onto a 20 cm ³ tapping cell to fill the cell volume, 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 density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the positive electrode active material in the present invention.

(5) Median diameter d50
The median diameter d50 (secondary particle diameter when primary particles are aggregated to form secondary particles) of the positive electrode active material particles can be measured using a laser diffraction / scattering particle size distribution analyzer. it can.
The median diameter d50 is preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 1 μm or more, particularly preferably 3 μm or more, preferably 30 μm or less, more preferably 20 μm or less, and more preferably 16 μm. The following is more preferable, and 15 μm or less is particularly preferable. When the median diameter d50 is within the above range, it becomes difficult to obtain a high bulk density product, and further, it does not take time for the diffusion of lithium in the particles, so that the battery characteristics are difficult to deteriorate. In addition, when forming a positive electrode of a battery, that is, when an active material, a conductive material, a binder, and the like are slurried with a solvent and applied in a thin film shape, streaking is less likely to occur.

In addition, the filling property at the time of positive electrode preparation can be further improved by mixing two or more types of positive electrode active materials having different median diameters d50 at an arbitrary ratio.
The median diameter d50 of the positive electrode active material was measured using a 0.1 mass% sodium hexametaphosphate aqueous solution as a dispersion medium, and using a particle size distribution analyzer (for example, LA-920 manufactured by Horiba, Ltd.), In contrast, after the ultrasonic dispersion for 5 minutes, the measurement refractive index is set to 1.24 and measured.

(6) Average primary particle diameter When primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.01 μm or more, more preferably 0.05 μm or more, It is more preferably 0.08 μm or more, particularly preferably 0.1 μm or more, and preferably 3 μm or less, more preferably 2 μm or less, still more preferably 1 μm or less, and particularly preferably 0.6 μm or less. Within the above range, it becomes easy to form spherical secondary particles, the powder filling property becomes appropriate, and a sufficient specific surface area can be secured, so that deterioration of battery performance such as output characteristics can be suppressed. .

  The average primary particle size of the positive electrode active material 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.

(7) BET specific surface area As for the BET specific surface area of the positive electrode active material, the value of the specific surface area measured using the BET method is preferably 0.2 m ² · g ⁻¹ or more, and 0.3 m ² · g ^−1. or more, and further preferably 0.4 m ² · ^{g -1} or higher, and preferably not more than 4.0m ² · ^{g -1,} 2.5m more preferably ² · ^{g -1} or less, 1.5 m ² · g ⁻¹ or less is more preferable. When the value of the BET specific surface area is within the above range, it is easy to prevent a decrease in battery performance. Furthermore, a sufficient tap density can be ensured, and the applicability at the time of forming the positive electrode active material becomes good.

  The BET specific surface area of the positive electrode active material is measured using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken). Specifically, the sample was pre-dried for 30 minutes at 150 ° C. under a nitrogen flow, and then the nitrogen-helium mixed gas accurately adjusted so that the relative pressure of nitrogen to the atmospheric pressure was 0.3. Is measured by a nitrogen adsorption BET one-point method using a gas flow method. The specific surface area determined by the measurement is defined as the BET specific surface area of the positive electrode active material in the present invention.

(8) Method for Producing Positive Electrode Active Material The method for producing the positive electrode active material is not particularly limited as long as it does not exceed the gist of the present invention, but there are several methods, which are common as methods for producing inorganic compounds. The method is used.
In particular, various methods are conceivable for producing a spherical or elliptical active material. For example, transition metal source materials such as transition metal nitrates and sulfates, and source materials of other elements as necessary. Is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to produce and recover a spherical precursor, which is dried as necessary, and then LiOH, Li ₂ CO ₃ , LiNO There is a method in which an active material is obtained by adding a Li source such as ₃ and baking at a high temperature.

In addition, as an example of another method, transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, oxides and the like, and if necessary, raw materials of other elements are dissolved or pulverized and dispersed in a solvent such as water. Then, it is dry-molded with a spray dryer or the like to obtain a spherical or oval spherical precursor, and a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ is added to the precursor and calcined at a high temperature to obtain an active material Is mentioned.

Examples of other methods include transition metal source materials such as transition metal nitrates, sulfates, hydroxides, oxides, Li sources such as LiOH, Li ₂ CO ₃ , LiNO ₃ , and other elements as necessary. The raw material is dissolved or pulverized and dispersed in a solvent such as water, and is then dried by a spray dryer or the like to form a spherical or elliptical precursor, which is fired at a high temperature to obtain an active material. Can be mentioned.

<2-3-2. Positive electrode structure and fabrication method>
Below, the structure of the positive electrode used for this invention and its preparation method are demonstrated.
(Production method of positive electrode)
The positive electrode is produced by forming a positive electrode active material layer containing positive electrode active material particles and a binder on a current collector. The production of the positive electrode using the positive electrode active material can be produced by any known method. For example, 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 dissolved in a liquid medium Alternatively, a positive electrode can be obtained by forming a positive electrode active material layer on the current collector by dispersing it as a slurry, applying this to a positive electrode current collector and drying it.

  The content of the positive electrode active material in the positive electrode active material layer is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and preferably 99.9% by mass or less. Yes, 99 mass% or less is more preferable. When the content of the positive electrode active material is within the above range, a sufficient electric capacity can be secured. Furthermore, the strength of the positive electrode is sufficient. In addition, the positive electrode active material powder in this invention may be used individually by 1 type, and may use together 2 or more types of a different composition or different powder physical properties by arbitrary combinations and ratios.

(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 carbonaceous 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 content of the conductive material in the positive electrode active material layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 1% by mass or more, and preferably 50% by mass or less. 30 mass% or less is more preferable, and 15 mass% or less is still more preferable. When the content is within the above range, sufficient conductivity can be secured. Furthermore, it is easy to prevent a decrease in battery capacity.

(binder)
The binder used for manufacturing the positive electrode active material layer 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 when manufacturing the electrode.
In the case of the coating method, it is not particularly limited as long as it is a material that is dissolved or dispersed in a liquid medium used at the time of electrode production. Specific examples include polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, and cellulose. Resin polymers such as nitrocellulose; rubbery polymers such as SBR (styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), fluorine rubber, isoprene rubber, butadiene rubber, ethylene propylene rubber; styrene butadiene Styrene block copolymer or hydrogenated product thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / ethylene copolymer, styrene / isoprene / styrene block copolymer or hydrogenated product thereof etc Thermoplastic elastomeric polymers; soft resinous polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride (PVdF) ), Fluorinated polymers such as polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer; polymer compositions having ionic conductivity of alkali metal ions (especially lithium ions), etc. It is done. 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 binder content in the positive electrode active material layer is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, and preferably 80% by mass or less. 60 mass% or less is more preferable, 40 mass% or less is still more preferable, and 10 mass% or less is especially preferable. When the ratio of the binder is within the above range, the positive electrode active material can be sufficiently retained, and the mechanical strength of the positive electrode can be secured, so that battery performance such as cycle characteristics is improved. Furthermore, it also leads to avoiding a decrease in battery capacity and conductivity.

(Liquid medium)
The liquid medium used for preparing the slurry for forming the positive electrode active material layer is a solvent that can dissolve or disperse the positive electrode active material, the conductive material, the binder, and the thickener used as necessary. If it exists, there is no restriction | limiting in particular in the kind, You may use either an aqueous solvent or an organic solvent.

  Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of organic media 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 and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) and dimethylformamide And amides such as dimethylacetamide; aprotic polar solvents such as hexamethylphosphalamide and dimethyl sulfoxide. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(Thickener)
When an aqueous medium is used as the liquid medium for forming the slurry, 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 limited as long as the effect of the present invention is not significantly limited. Specifically, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein and salts thereof Etc. 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 used, the ratio of the thickener to the positive electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further 0.6% by mass or more. It is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less. When the content is within the above range, the coating property is improved, and further, the ratio of the active material in the positive electrode active material layer becomes sufficient, so that the problem that the battery capacity decreases and the resistance between the positive electrode active materials increases. It is easier to avoid problems.

(Consolidation)
In order to increase the packing density of the positive electrode active material, the positive electrode active material layer obtained by applying the slurry to the current collector and drying is preferably consolidated by a hand press, a roller press or the like. The density of the positive electrode active material layer is preferably 1 g · cm ⁻³ or more, more preferably 1.5 g · cm ⁻³ or more, particularly preferably 2 g · cm ⁻³ or more, and preferably 4 g · cm ⁻³ or less. 3.5 g · cm ⁻³ or less is more preferable, and 3 g · cm ⁻³ or less is particularly preferable. When the density of the positive electrode active material layer is within the above range, the non-aqueous electrolyte solution permeation into the vicinity of the current collector / active material interface does not decrease, and the charge / discharge characteristics particularly at a high current density are good. Become. Furthermore, the electrical conductivity between the active materials is difficult to decrease, and the battery resistance is difficult to increase.

(Current collector)
There is no restriction | limiting in particular as a material of a positive electrode electrical power collector, A well-known thing can be used arbitrarily. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbonaceous 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, foam metal, etc. A carbon 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.
The thickness of the current collector is arbitrary, but is preferably 1 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, and preferably 1 mm or less, more preferably 100 μm or less, and further preferably 50 μm or less. preferable. When the thickness of the current collector is within the above range, sufficient strength required for the current collector can be ensured. Furthermore, the handleability is also improved.

The thickness ratio between the current collector and the positive electrode active material layer is not particularly limited, but (active material layer thickness on one side immediately before non-aqueous electrolyte injection) / (current collector thickness) is preferably 150 or less, more preferably 20 or less, particularly preferably 10 or less, preferably 0.1 or more, more preferably 0.4 or more, and particularly preferably 1 or more.
When the ratio of the thickness of the current collector to the positive electrode active material layer is within the above range, the current collector hardly generates heat due to Joule heat during high current density charge / discharge. Furthermore, the volume ratio of the current collector to the positive electrode active material is difficult to increase, and the battery capacity can be prevented from decreasing.

(Electrode area)
From the viewpoint of increasing the stability at high output and high temperature, the area of the positive electrode active material layer is preferably larger than the outer surface area of the battery outer case. Specifically, the total electrode area of the positive electrode with respect to the surface area of the exterior of the non-aqueous electrolyte secondary battery is preferably 20 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. , The sum of the areas where each surface is calculated separately.

(Discharge capacity)
When the non-aqueous electrolyte of the present invention is used, the electric capacity of the battery element housed in one battery exterior of the non-aqueous electrolyte secondary battery (electric capacity when the battery is discharged from a fully charged state to a discharged state) ) Is 1 ampere hour (Ah) or more, since the effect of improving the low temperature discharge characteristics is increased. Therefore, the positive electrode plate is designed so that the discharge capacity is fully charged, preferably 3 Ah (ampere hour), more preferably 4 Ah or more, preferably 20 Ah or less, more preferably 10 Ah or less.

  Within the above range, the voltage drop due to the electrode reaction resistance does not become excessive when a large current is taken out, and the deterioration of the power efficiency can be prevented. Furthermore, the temperature distribution due to the internal heat generation of the battery during pulse charge / discharge does not become too large, the durability of repeated charge / discharge is inferior, and the heat dissipation efficiency is poor against sudden heat generation during abnormalities such as overcharge and internal short circuit. The phenomenon of becoming can be avoided.

(Thickness of positive plate)
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity, high output, and high rate characteristics, the thickness of the positive electrode active material layer minus the thickness of the current collector is relative to one side of the current collector. 10 μm or more is preferable, 20 μm or more is more preferable, 200 μm or less is preferable, and 100 μm or less is more preferable.

<2-4. Negative electrode>
The negative electrode active material used for the negative electrode is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples thereof include carbonaceous materials, metal compound materials, lithium-containing metal composite oxide materials, and the like. One of these may be used alone, or two or more may be used in any combination.

<2-4-1. Carbonaceous material>
The carbonaceous material used as the negative electrode active material is not particularly limited, but a material selected from the following (A) to (D) is preferable because it has a good balance between initial irreversible capacity and high current density charge / discharge characteristics.
(A) Natural graphite (I) Artificial carbonaceous material and carbonaceous material obtained by heat treating artificial graphite material at least once in the range of 400 to 3200 ° C. (C) The negative electrode active material layer has at least two different crystallinities. (D) a negative electrode active material layer comprising carbonaceous materials having at least two different orientations, and / or a carbonaceous material having an interface with which the different crystalline carbonaceous materials are in contact. And / or the carbonaceous materials (a) to (d) having an interface with which the carbonaceous materials having different orientations are in contact may be used alone or in any combination of two or more. And may be used in combination in a ratio.

Specific examples of the artificial carbonaceous material or artificial graphite material of (i) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch and those pitch-oxidized, needle coke, Pitch coke and carbon materials partially graphitized thereof, furnace black, acetylene black, pyrolysis products of organic substances such as pitch-based carbon fibers, carbonizable organic substances and their carbides, and carbonizable organic substances as benzene, toluene, Examples include solution-like carbides dissolved in low-molecular organic solvents such as xylene, quinoline, and n-hexane.
As for the properties of the carbonaceous material, it is desirable that any one or a plurality of items (1) to (8) shown below are satisfied at the same time.

(1) X-ray parameters The d-value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method of carbonaceous materials is preferably 0.335 nm or more, and is usually 0.8. It is 360 nm or less, preferably 0.350 nm or less, and more preferably 0.345 nm or less. The crystallite size (Lc) determined by X-ray diffraction by the Gakushin method is preferably 1.0 nm or more, more preferably 1.5 nm or more, and still more preferably 2 nm or more.

(2) Volume-based average particle diameter The volume-based average particle diameter of the carbonaceous material is usually 1 μm or more, and more preferably 3 μm or more, based on the volume-based average particle diameter (median diameter) determined by the laser diffraction / scattering method. It is more preferably 5 μm or more, particularly preferably 7 μm or more, preferably 100 μm or less, more preferably 50 μm or less, further preferably 40 μm or less, particularly preferably 30 μm or less, and particularly preferably 25 μm or less. When the volume reference average particle diameter is within the above range, the irreversible capacity does not increase excessively, and it is easy to avoid incurring loss of the initial battery capacity. In addition, when an electrode is produced by coating, it is easy to uniformly coat the surface, which is desirable in the battery manufacturing process.

  In order to measure the volume-based average particle size, a carbonaceous material powder is dispersed in a 0.2% by mass aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, and laser diffraction / A scattering type particle size distribution meter (LA-700 manufactured by Horiba, Ltd.) is used. The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material.

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

When the Raman R value is in the above range, the crystallinity of the particle surface is in an appropriate range, and it is possible to suppress a decrease in sites where Li enters between layers with charge / discharge, and charge acceptability is hardly lowered. Further, even when the negative electrode is densified by applying it to the current collector and then pressing it, it is difficult to cause a decrease in load characteristics. Furthermore, it is difficult to cause a decrease in efficiency and an increase in gas generation.
Moreover, the Raman half-width in the vicinity of 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and is usually 100 cm ⁻¹ or less, and 80 cm ⁻¹ or less. Preferably, 60 cm ⁻¹ or less is more preferable, and 40 cm ⁻¹ or less is particularly preferable.

When the Raman half width is in the above range, the crystallinity of the particle surface is in an appropriate range, and the decrease in the sites where Li enters between the layers can be suppressed with charge / discharge, and the charge acceptability is hardly lowered. Further, even when the negative electrode is densified by applying it to the current collector and then pressing it, it is difficult to cause a decrease in load characteristics. Furthermore, it is difficult to cause a decrease in efficiency and an increase in gas generation.
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 the sample surface in the cell is irradiated 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 _{I A} of the peak _{P A} in the vicinity of 1580 cm ^-1, and measuring the intensity _{I B} of a peak _{P B} in the vicinity of 1360 cm ^-1, the intensity ratio _{R (R = I B / I} A) Is calculated. The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material in the present invention. Further, the half width of the peak P _A in the vicinity of 1580 cm ^-1 of the resulting Raman spectrum was measured, which is defined as the Raman half-value width of the carbonaceous material in the present invention.

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: 1100cm ^-1 ~1730cm -1 · Raman R value, Raman half-value width Analysis: Background processing, smoothing processing: simple average, convolution 5 points

(4) BET specific surface area As for the BET specific surface area of the carbonaceous material, the value of the specific surface area measured using the BET method is preferably 0.1 m ² · g ⁻¹ or more, and 0.7 m ² · g ^−1. The above is more preferable, 1.0 m ² · g ⁻¹ or more is further preferable, 1.5 m ² · g ⁻¹ or more is particularly preferable, and preferably 100 m ² · g ⁻¹ or less, and 25 m ² · g ^{−. 1} or less is more preferable, 15 m ² · g ⁻¹ or less is more preferable, and 10 m ² · g ⁻¹ or less is particularly preferable.

  When the value of the BET specific surface area is within the above range, the acceptability of cations such as lithium is good at the time of charging when used as a negative electrode material, lithium and the like are difficult to deposit on the electrode surface, and the stability is avoided. Cheap. further. The reactivity with the non-aqueous electrolyte can be suppressed, gas generation is small, and a preferable battery is easily obtained.

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. The specific surface area determined by the measurement is defined as the BET specific surface area of the carbonaceous material in the present invention.

(5) Circularity When the circularity is measured as a spherical degree 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.
It is desirable that the circularity of particles having a carbonaceous material particle size in the range of 3 to 40 μm is closer to 1. Preferably it is 0.1 or more, 0.5 or more is more preferable, 0.8 or more is further more preferable, 0.85 or more is especially preferable, and 0.9 or more is especially preferable.

High current density charge / discharge characteristics generally improve as the circularity increases. Therefore, when the circularity is less than the above range, the filling property of the negative electrode active material is lowered, the resistance between particles is increased, and the high current density charge / discharge characteristics may be lowered for a short time.
The circularity of the carbonaceous material is measured using a flow particle image analyzer (FPIA manufactured by Sysmex Corporation). Specifically, about 0.2 g of a sample is dispersed in a 0.2 mass% aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and an ultrasonic wave of 28 kHz is output at 60 W for 1 After irradiating for minutes, the detection range is specified as 0.6 to 400 μm, and the particle size is measured for particles in the range of 3 to 40 μm. The circularity obtained by the measurement is defined as the circularity of the carbonaceous material in the present invention.

  The method for improving the degree of circularity is not particularly limited, but a spheroidized 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 approximating a sphere by applying a shearing force and a compressive force, a mechanical / physical processing method of granulating a plurality of fine particles by an adhesive force possessed by a binder or particles, etc. Is mentioned.

(6) The tap density of the tap density carbonaceous material, preferably at 0.1 g · ^{cm -3} or more, 0.5 g · ^{cm -3} or more, and more preferably 0.7 g · ^{cm -3} or more, 1 g · cm ⁻³ or more is particularly preferable. Moreover, 2 g * cm <^-3> or less is preferable, 1.8 g * cm < ^-3 > or less is more preferable, and 1.6 g * cm <^-3> or less is especially preferable.

When the tap density is within the above range, a sufficient packing density can be secured when used as a negative electrode, and a high-capacity battery can be obtained. Furthermore, voids between the particles in the electrode are not reduced too much, conductivity between the particles is ensured, and preferable battery characteristics are easily obtained.
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 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 volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the carbonaceous material in the present invention.

(7) Orientation ratio The orientation ratio of the carbonaceous material is preferably 0.005 or more, more preferably 0.01 or more, still more preferably 0.015 or more, and preferably 0.67 or less. When the orientation ratio is below the above range, the high-density charge / discharge characteristics may deteriorate. The upper limit of the above range is the theoretical upper limit value of the orientation ratio of the carbonaceous material.

The orientation ratio of the carbonaceous material is obtained by measuring by X-ray diffraction after pressure-molding the sample. Specifically, a molded body obtained by filling 0.47 g of a sample into a molding machine having a diameter of 17 mm and compressing with a 58.8 MN · m ⁻² is flush with the surface of the measurement sample holder using clay. Then, the X-ray diffraction is measured. From the (110) diffraction and (004) diffraction peak intensities of the obtained carbonaceous material, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated. The orientation ratio calculated by the measurement is defined as the orientation ratio of the carbonaceous material in the present invention.

The X-ray diffraction measurement conditions at this time 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 degrees Measurement range and step angle / measurement time:
(110) plane: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) plane: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds

(8) Aspect ratio (powder)
The aspect ratio of the carbonaceous material is usually 1 or more and usually 10 or less, preferably 8 or less, more preferably 5 or less. If the aspect ratio is out of the above range, streaking may occur when forming an electrode plate, a uniform coated surface may not be obtained, and high current density charge / discharge characteristics may be deteriorated. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the carbonaceous material.

  The aspect ratio of the carbonaceous material is measured by magnifying and observing the carbonaceous material particles with a scanning electron microscope. Specifically, arbitrary 50 carbonaceous material particles fixed to the end face of a metal having a thickness of 50 microns or less are selected, and the stage on which the sample is fixed is rotated and tilted, and observed three-dimensionally. Then, the longest diameter A of the carbonaceous material particles and the shortest diameter B orthogonal thereto are measured, and the average value of A / B is obtained. The aspect ratio (A / B) obtained by the measurement is defined as the aspect ratio of the carbonaceous material in the present invention.

<2-4-2. Metal compound materials>
The metal compound-based material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, and is a single metal or alloy that forms a lithium alloy, or oxides, carbides, nitrides, silicides thereof. Compounds such as oxides, sulfides and phosphides. Examples of such metal compounds include compounds containing metals such as Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, and Zn. Especially, it is preferable that it is a single metal or alloy which forms a lithium alloy, and it is more preferable that there is a material containing a metal / metalloid element (that is, excluding carbon) of Group 13 or Group 14 of the periodic table. (Si), tin (Sn), or lead (Pb) (hereinafter, these three elements may be referred to as “SSP metal elements”), simple metals, alloys containing these atoms, or their metals (SSP metals) Element). These may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the negative electrode active material having at least one kind of atom selected from SSP metal elements include a single metal of any one SSP metal element, an alloy composed of two or more SSP metal elements, one kind or two or more kinds. Alloys composed of SSP metal elements and other one or more metal elements, and compounds containing one or more SSP metal elements, or oxides, carbides, and nitrides of the compounds , Compound compounds such as silicides, sulfides and phosphides. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

  Moreover, the compound which these complex compounds combined with several elements, such as a metal simple substance, an alloy, or a nonmetallic element, can also be mentioned as an example. More 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. In addition, 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 can also be used. .

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

In addition, although the capacity per unit mass is inferior to that of using a single metal or an alloy, the following compounds containing silicon and / or tin are also preferred because of excellent cycle characteristics.
The element ratio of silicon and / or tin to oxygen is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. “Silicon and / or tin oxide” of 3 or less, more preferably 1.1 or less.
-Element ratio of silicon and / or tin and nitrogen is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. “Silicon and / or tin nitride” of 3 or less, more preferably 1.1 or less.
The elemental ratio of silicon and / or tin to carbon is usually 0.5 or more, preferably 0.7 or more, more preferably 0.9 or more, and usually 1.5 or less, preferably 1. “Carbide of silicon and / or tin” of 3 or less, more preferably 1.1 or less.
In addition, any one of the above-described negative electrode active materials may be used alone, or two or more thereof may be used in any combination and ratio.

<2-4-3. Lithium-containing metal composite oxide material>
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 lithium-containing composite metal oxide materials containing titanium are preferable, and lithium and titanium composite oxidation (Hereinafter sometimes abbreviated as “lithium titanium composite oxide”) is particularly preferable. 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 lithium ion non-aqueous electrolyte secondary 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 as the negative electrode active material is a lithium titanium composite oxide represented by the following general formula (A), and 0.7 ≦ x ≦ 1.5, 1.5 in the general formula (A) It is preferable that ≦ y ≦ 2.3 and 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 is selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb) Represents at least one element.)
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), and 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.
In addition to the above requirements, the lithium titanium composite oxide as the negative electrode active material in the present invention further satisfies at least one of the characteristics such as physical properties and shapes shown in the following [1] to [8]. It is preferable to satisfy a plurality of items at the same time.

[1] BET specific surface area The BET specific surface area of the lithium-titanium composite oxide used as the negative electrode active material is preferably 0.5 m ² · g ⁻¹ or more as measured by the BET method. 7 m ² · g ⁻¹ or more is more preferred, 1.0 m ² · g ⁻¹ or more is more preferred, 1.5 m ² · g ⁻¹ or more is particularly preferred, and 200 m ² · g ⁻¹ or less is preferred, 100 m ² · g ⁻¹ or less is more preferred, 50 m ² · g ⁻¹ or less is more preferred, and 25 m ² · g ⁻¹ or less is particularly preferred.

When the BET specific surface area is within the above range, the reaction area in contact with the non-aqueous electrolyte when used as the negative electrode material is unlikely to decrease, and the output resistance can be prevented from increasing. Furthermore, since the increase in the surface and end face portions of the metal oxide crystal containing titanium is suppressed and the resulting crystal distortion is less likely to occur, a preferable battery is easily obtained.
The specific surface area of the lithium-titanium composite oxide was preliminarily dried at 350 ° C. for 15 minutes under a nitrogen flow using a surface area meter (a fully automatic surface area measuring device manufactured by Rikura Okura) using a surface area meter. Thereafter, a nitrogen adsorption BET one-point method using a gas flow method is performed using a nitrogen helium mixed gas that is accurately adjusted so that the value of the relative pressure of nitrogen with respect to atmospheric pressure is 0.3. The specific surface area determined by the measurement is defined as the BET specific surface area of the lithium titanium composite oxide in the present invention.

[2] Volume-based average particle size The volume-based average particle size of the lithium-titanium composite oxide (secondary particle size when primary particles are aggregated to form secondary particles) is determined by the laser diffraction / scattering method. It is defined by the obtained volume-based average particle diameter (median diameter).
The volume-based average particle diameter of the lithium titanium composite oxide is preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 0.7 μm or more, more preferably 50 μm or less, more preferably 40 μm or less, and 30 μm. The following is more preferable, and 25 μm or less is particularly preferable.

Specifically, the volume-based average particle diameter of the lithium-titanium composite oxide was measured by adding a lithium-titanium composite oxide to a 0.2% by mass aqueous solution (10 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant. The powder is dispersed and the measurement is performed using a laser diffraction / scattering particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). The median diameter determined by the measurement is defined as the volume-based average particle diameter of the lithium titanium composite oxide.
When the volume average particle size of the lithium titanium composite oxide is within the above range, the amount of the binder can be suppressed during the production of the negative electrode, and as a result, it is easy to prevent the battery capacity from being lowered. Furthermore, when forming a negative electrode plate, a uniform coating surface is likely to be obtained, which is desirable in the battery manufacturing process.

[3] Average primary particle diameter When primary particles are aggregated to form secondary particles, the average primary particle diameter of the lithium titanium composite oxide is preferably 0.01 μm or more, more preferably 0.05 μm or more. Preferably, 0.1 μm or more is more preferable, 0.2 μm or more is particularly preferable, 2 μm or less is preferable, 1.6 μm or less is more preferable, 1.3 μm or less is further preferable, and 1 μm or less is particularly preferable. When the volume-based average primary particle diameter is within the above range, spherical secondary particles are easily formed and the specific surface area is easily secured, so that it is easy to prevent a decrease in battery performance such as output characteristics.

  In addition, the primary particle diameter of lithium titanium complex oxide is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification at which particles can be confirmed, for example, a magnification of 10,000 to 100,000 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 determined for any 50 primary particles. Obtained and obtained by taking an average value.

[4] Shape The shape of the lithium-titanium composite oxide particles may be any of lump shape, polyhedron shape, spherical shape, elliptical spherical shape, plate shape, needle shape, columnar shape, etc. as used in the past. Thus, it is preferable to form secondary particles, and the shape of the secondary particles is spherical or elliptical.

In general, an electrochemical element expands and contracts as the active material in the electrode expands and contracts as it is charged and discharged. Therefore, the active material is easily damaged due to the stress or the conductive path is broken. Therefore, it is possible to relieve the stress of expansion and contraction and prevent deterioration when the primary particles are aggregated to form secondary particles, rather than being a single particle active material consisting of only primary particles.
In addition, spherical or oval spherical particles are less oriented during molding of the electrode than plate-like equiaxed particles, so there is less expansion and contraction of the electrode during charge and discharge, and an electrode is produced. The mixing with the conductive material is also preferable because it can be easily mixed uniformly.

[5] The tap density of the tap density lithium-titanium composite oxide is preferably from 0.05 g · ^{cm -3} or more, 0.1 g · ^{cm -3} or more, and more preferably 0.2 g · ^{cm -3} or more, 0.4 g · cm ⁻³ or more is particularly preferable, 2.8 g · cm ⁻³ or less is preferable, 2.4 g · cm ⁻³ or less is further preferable, and 2 g · cm ⁻³ or less is particularly preferable. When the tap density of the lithium-titanium composite oxide is within the above range, a sufficient packing density can be secured when used as a negative electrode, and a contact area between the particles can be secured, so that the resistance between the particles hardly increases. It is easy to prevent the output resistance from increasing. Furthermore, since the space between the particles in the electrode is also appropriate, the flow path of the non-aqueous electrolyte solution can be secured, so that it is easy to prevent an increase in output resistance.

To measure the tap density of the lithium-titanium composite oxide, the sample is passed through a sieve having a mesh size of 300 μm, dropped into a 20 cm ³ tapping cell and filled up to the upper end surface of the cell, and then a powder density measuring device. Using, for example, a tap denser manufactured by Seishin Enterprise Co., Ltd., tapping with a stroke length of 10 mm is performed 1000 times, and the density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the lithium titanium composite oxide in the present invention.

[6] Circularity When the circularity is measured as the spherical degree of the lithium titanium composite oxide, 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 lithium-titanium composite oxide is preferably closer to 1. Preferably, 0.10
It is above, 0.80 or more is more preferable, 0.85 or more is still more preferable, and 0.90 or more is especially preferable. High current density charge / discharge characteristics generally improve as the circularity increases. Therefore, when the circularity is within the above range, the filling property of the negative electrode active material is not lowered, the increase in resistance between particles can be prevented, and the short time high current density charge / discharge characteristics can be prevented.

  The circularity of the lithium titanium composite oxide is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). Specifically, about 0.2 g of a sample is dispersed in a 0.2 mass% aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and an ultrasonic wave of 28 kHz is output at 60 W for 1 After irradiating for minutes, the detection range is specified as 0.6 to 400 μm, and the particle size is measured for particles in the range of 3 to 40 μm. The circularity obtained by the measurement is defined as the circularity of the lithium titanium composite oxide in the present invention.

[7] Aspect ratio The aspect ratio of the lithium titanium composite oxide is preferably 1 or more, preferably 5 or less, more preferably 4 or less, still more preferably 3 or less, and particularly preferably 2 or less. When the aspect ratio is within the above range, streaking is less likely to occur when forming an electrode plate, and a uniform coated surface can be easily obtained, so that it is possible to prevent deterioration of high current density charge / discharge characteristics for a short time. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the lithium titanium composite oxide.

  The aspect ratio of the lithium titanium composite oxide is measured by magnifying and observing the particles of the lithium titanium composite oxide with a scanning electron microscope. When 50 arbitrary lithium-titanium composite oxide particles fixed to the end face of a metal having a thickness of 50 μm or less are selected, and the stage on which the sample is fixed is rotated and tilted, and three-dimensional observation is performed. The longest diameter A of the particles and the shortest diameter B orthogonal to the same are measured, and the average value of A / B is obtained. The aspect ratio (A / B) determined by the measurement is defined as the aspect ratio of the lithium titanium composite oxide in the present invention.

[8] Method for producing lithium-titanium composite oxide The method for producing lithium-titanium composite oxide is not particularly limited as long as it does not exceed the gist of the present invention. A general method is used.
For example, a method of obtaining an active material by uniformly mixing a titanium source material such as titanium oxide and a source material of another element and a Li source such as LiOH, Li ₂ CO ₃ , or LiNO ₃ as necessary, and firing at a high temperature. Is mentioned.

In particular, various methods are conceivable for producing a spherical or elliptical active material. As an example, a titanium precursor material such as titanium oxide and, if necessary, a raw material material of another element are dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to create a spherical precursor. There is a method in which the active material is obtained by recovering and drying it as necessary, and then adding a Li source such as LiOH, Li ₂ CO ₃ , or LiNO ₃ and baking at a high temperature.

As another example, a titanium raw material such as titanium oxide and, if necessary, a raw material of another element are dissolved or pulverized and dispersed in a solvent such as water. A method of obtaining an active material by adding a Li source such as LiOH, Li ₂ CO ₃ , LiNO _{3 and the} like to an elliptical spherical precursor and baking at a high temperature can be mentioned.
As yet another method, a titanium raw material such as titanium oxide, a Li source such as LiOH, Li ₂ CO ₃ and LiNO ₃ and a raw material of another element as necessary are dissolved or pulverized in a solvent such as water. There is a method in which it is dispersed and dried by a spray dryer or the like to obtain a spherical or elliptical precursor, which is then fired at a high temperature to obtain an active material.

  Also, during these steps, elements other than Ti, such as Al, Mn, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, C, Si, Sn , Ag may be present in the metal oxide structure containing titanium and / or in contact with the oxide containing titanium. By containing these elements, the operating voltage and capacity of the battery can be controlled.

<2-4-4. Structure, physical properties and preparation method of negative electrode>
For the negative electrode containing the above active material, electrode forming method, current collector, and non-aqueous electrolyte secondary battery, one or more items of (i) to (vi) shown below are simultaneously satisfied It is desirable that

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

(Ii) 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, and 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.

In addition, when the thickness of the copper foil is less than 25 μm, a copper alloy (phosphor bronze, titanium copper, Corson alloy, Cu—Cr—Zr alloy, etc.) having higher strength than pure copper can be used.
(Iii) Ratio of thickness of current collector and negative electrode active material layer The ratio of thickness of current collector and negative electrode active material layer is not particularly limited, but “(one side just before the non-aqueous electrolyte injection step) Negative electrode active material layer thickness) / (current collector thickness) "is preferably 150 or less, more preferably 20 or less, particularly preferably 10 or less, and more preferably 0.1 or more. 4 or more is more 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 exceeds the above range, the current collector may generate heat due to Joule heat during high current density charge / discharge. On the other hand, below the above range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease.

(Iv) Electrode density The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, and the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more. .2g · ^{cm -3} or more preferably, 1.3 g · ^{cm -3} or more, and also preferably 4g · ^{cm -3} or less, more preferably 3 g · ^{cm -3} or less, 2.5 g · cm ^{- 3} or less is more preferable, and 1.7 g · cm ⁻³ or less is particularly preferable. When the density of the negative electrode active material existing on the current collector is within the above range, the negative electrode active material particles are less likely to be destroyed, and the increase in initial irreversible capacity and the vicinity of the current collector / negative electrode active material interface It becomes easy to prevent deterioration of high current density charge / discharge characteristics due to a decrease in permeability of the non-aqueous electrolyte. Further, the conductivity between the negative electrode active materials can be secured, and the capacity per unit volume can be earned without increasing the battery resistance.

(V) Binder / Solvent, etc. The slurry for forming the negative electrode active material layer is usually prepared by adding a binder (binder), a thickener and the like to the solvent with respect to the negative electrode active material.
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, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, NBR ( Acrylonitrile / butadiene rubber), rubbery polymers such as ethylene / propylene rubber; styrene / butadiene / styrene block copolymers or hydrogenated products thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / Thermoplastic elastomeric polymer such as butadiene / styrene copolymer, styrene / isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene Soft resinous polymers such as vinyl acetate copolymer and propylene / α-olefin copolymer; Fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene / ethylene copolymer Polymers: Polymer compositions having ionic conductivity of alkali metal ions (particularly lithium ions), and the like. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

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, alcohol and the like, and examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N , N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, etc. .

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.
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, still more preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10 mass% or less is still more preferable, and 8 mass% or less is especially preferable. When the ratio of the binder to the negative electrode active material is within the above range, the ratio of the binder that does not contribute to the battery capacity does not increase, so that the battery capacity is hardly reduced. Furthermore, the strength of the negative electrode is hardly lowered.

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

  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 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, and 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 within the above range, the coating property is good. Furthermore, the ratio of the negative electrode active material in the negative electrode active material layer is also moderate, and the problem of a decrease in battery capacity and a problem of an increase in resistance between the negative electrode active materials are less likely to occur.

(Vi) Area of Negative Electrode Plate The area of the negative electrode plate is not particularly limited, but it is preferably designed to be slightly larger than the opposing positive electrode plate so that the positive electrode plate does not protrude from the negative electrode plate. Further, from the viewpoint of suppressing the life of a cycle in which charge and discharge are repeated and deterioration due to high temperature storage, it is preferable that the area be as close to the positive electrode as possible, because the ratio of electrodes that work more uniformly and effectively is increased and the characteristics are improved. In particular, when used with a large current, the design of the area of the negative electrode plate is important.

<2-5. Separator>
Usually, 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.
There is no restriction | limiting in particular about the material and shape of a separator, As long as the effect of this invention is not impaired remarkably, a well-known thing can be employ | adopted arbitrarily. 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, aramid resins, 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 preferably 1 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. . When the thickness of the separator is within the above range, the insulation and mechanical strength are good. Furthermore, the battery performance such as rate characteristics can be prevented from being lowered, and the energy density of the non-aqueous electrolyte secondary battery as a whole can be prevented from being lowered.

  Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is preferably 20% or more, more preferably 35% or more, and further 45% or more. Preferably, it is 90% or less, more preferably 85% or less, and further preferably 75% or less. When the porosity is within the above range, the membrane resistance does not increase excessively, and deterioration of rate characteristics can be suppressed. Furthermore, the mechanical strength of the separator becomes appropriate, and the deterioration of the insulation can be suppressed.

Moreover, although the average pore diameter of a separator is also arbitrary, Preferably it is 0.5 micrometer or less, 0.2 micrometer or less is more preferable, Preferably it is 0.05 micrometer or more. When the average pore diameter is within the above range, short circuit is difficult to occur. Furthermore, the film resistance is not increased too much, and the rate characteristics can be prevented from deteriorating.
On the other hand, as the inorganic material, 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. Things are used.

  As a form of the separator, a thin film shape such as a nonwoven 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 independent thin film shape, a separator formed by forming a composite porous layer containing 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.

<2-6. Battery design>
(Electrode group)
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed via the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape via the separator. Either may be used. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as electrode group occupancy) is preferably 40% or more, more preferably 50% or more, and preferably 95% or less, 90% The following is more preferable. When the electrode group occupancy is within the above range, the battery capacity is difficult to decrease. In addition, since an appropriate gap space can be secured, the member expands due to the high temperature of the battery or the vapor pressure of the liquid component of the electrolyte increases, and the internal pressure rises. Various characteristics such as high-temperature storage can be deteriorated, and further, a case where a gas release valve that releases the internal pressure to the outside can be avoided.

(Current collection structure)
The current collecting structure is not particularly limited, but in order to more effectively realize the improvement of the discharge characteristics by the non-aqueous electrolyte solution of the present invention, it is necessary to make the structure to reduce the resistance of the wiring part and the joint part. preferable. Thus, when internal resistance is reduced, the effect of using the non-aqueous electrolyte solution of this invention is exhibited especially favorable.

  In the case where the electrode group has the laminated structure described above, 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 reduce the resistance by providing a plurality of terminals in the electrode. 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.

(Protective element)
Protection elements such as PTC (Positive Temperature Coefficient), thermal fuse, thermistor, which increases resistance when abnormal heat is generated or excessive current flows, shuts off current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature during abnormal heat generation And the like (current cutoff valve). 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 has a design that does not cause abnormal heat generation or thermal runaway even without the protective element.

(Exterior body)
The non-aqueous electrolyte secondary battery of the present invention is usually configured by housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body (exterior case). There is no restriction | limiting in this exterior body, As long as the effect of this invention is not impaired remarkably, a well-known thing can be employ | adopted arbitrarily.
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 or an aluminum alloy, a magnesium alloy, nickel, titanium, or a metal, 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 the outer case using the above metals, the metal is welded to each other by laser welding, resistance welding, ultrasonic welding, or a sealed sealing structure, or a caulking structure using the above metals through a resin gasket To do. 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 Resins are preferably used.
The shape of the outer case 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.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples, unless the summary is exceeded.
<Examples 1-1 to 1-2, Comparative Examples 1-1 to 1-4>
[Preparation of non-aqueous electrolyte secondary battery]

<Preparation of positive electrode>
72 parts by mass of lithium manganate (Li _1.1 Mn _1.9 Al _0.1 O ₄ ) as the first positive electrode active material, lithium nickel manganese cobalt composite oxide (Li _{1. 15} Ni _0.45 Mn _0.45 Co _0.10 O ₂ ), 18 parts by mass, 5 parts by mass of carbon black as a conductive agent, 5 parts by mass of polyvinylidene fluoride (PVdF) as a binder, N -After mixing and slurrying in methyl-2-pyrrolidone, this was uniformly applied to an aluminum foil having a thickness of 15 μm and dried, and then roll-pressed to obtain a positive electrode.

<Production of negative electrode>
98 parts by mass of graphite powder, 1 part by mass of carbon black as a conductive agent, and 6 parts by mass of polyvinylidene fluoride (PVdF) as a binder were mixed and slurried in N-methyl-2-pyrrolidone. It was uniformly applied to a copper foil having a thickness of 12 μm, dried, and roll-pressed to obtain a negative electrode.

<Manufacture of non-aqueous electrolyte secondary battery>
The positive electrode, the negative electrode, and the polyolefin separator were laminated in the order of the negative electrode, the separator, and the positive electrode. The battery element thus obtained was wrapped in an aluminum laminate film, injected with an electrolyte solution described later, and then vacuum sealed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of non-aqueous electrolyte secondary battery]
Initial charge / discharge In a constant temperature bath of 25 ° C., sheet-like non-aqueous electrolyte secondary battery is 0.1 C (the rated capacity with a discharge capacity of 1 hour rate is 1 C. The current value is 1 C. The same applies hereinafter. )) To a constant current-constant voltage up to 4.2V, and then discharged to 3.0V at 0.1C. Then 4.2 at 0.33C
After charging at constant current-constant voltage to V, it was discharged to 3.0 V at 0.33C. This was carried out for 2 cycles for a total of 3 cycles to stabilize the non-aqueous electrolyte secondary battery. The last discharge capacity was defined as “initial capacity”.

-High-temperature cycle test In a constant temperature bath at 55 ° C, a constant current-constant voltage charge at 1 C to 4.2 V was performed, and a process of discharging to 2.7 V at a constant current of 1 C was performed as 30 cycles. The capacity at the 30th cycle was defined as “capacity after cycle”.
[Example 1-1]
In a dry argon atmosphere, 1 mol / L (as a concentration in the non-aqueous electrolyte) of LiPF ₆ that was sufficiently dried was dissolved in a mixture of ethylene carbonate and diethyl carbonate (volume ratio 3: 7). Dried 1,6-diisocyanatohexane (DIH) with 0.5% by mass (as a concentration in the non-aqueous electrolyte) and sufficiently dried 4-fluoro-1,3-dioxolan-2-one ( FEC) is dissolved in 1% by mass (as a concentration in the non-aqueous electrolyte solution) and 0.5% by mass (as a concentration in the non-aqueous electrolyte solution) of vinylene carbonate (VC) that has been sufficiently dried to dissolve the non-aqueous electrolyte solution. Was prepared. A battery was prepared by the above-described method using this nonaqueous electrolytic solution, and the above evaluation was performed.

[Example 1-2]
A battery as in Example 1-1, except that 0.2% by mass (as a concentration in the non-aqueous electrolyte) of succinic anhydride (SucA) was dissolved in the non-aqueous electrolyte instead of vinylene carbonate (VC). The above evaluation was carried out.
[Comparative Example 1-1]
Example 1 except that 1,6-diisocyanatohexane (DIH), 4-fluoro-1,3-dioxolan-2-one (FEC) and vinylene carbonate (VC) were not dissolved in the nonaqueous electrolytic solution. A battery was prepared in the same manner as in Example 1, and the above evaluation was performed.

[Comparative Example 1-2]
A battery was prepared in the same manner as in Example 1-1 except that 4-fluoro-1,3-dioxolan-2-one (FEC) and vinylene carbonate (VC) were not dissolved in the nonaqueous electrolytic solution, and the above evaluation was performed. Carried out.
[Comparative Example 1-3]
A battery was prepared in the same manner as in Example 1-1 except that 1,6-diisocyanatohexane (DIH) and vinylene carbonate (VC) were not dissolved in the nonaqueous electrolytic solution, and the above evaluation was performed.

[Comparative Example 1-4]
4-fluoro-1,3-dioxolan-2-one (FEC) is not dissolved in the nonaqueous electrolytic solution, and 1% by mass of vinylene carbonate (VC) in the nonaqueous electrolytic solution (concentration in the nonaqueous electrolytic solution). ) A battery was prepared in the same manner as in Example 1-1 except that it was dissolved, and the above evaluation was performed.
Table 1 below shows the initial capacity and post-cycle capacity normalized by the value of Comparative Example 1-1.

  As is apparent from Table 1, in the non-aqueous electrolyte solution, a compound selected from the group consisting of “unsaturated carbonate” and “specific cyclic compound”, a fluorine-containing ethylene carbonate derivative, and further, “specific CN compound” In the non-aqueous electrolyte secondary battery prepared using the non-aqueous electrolyte solution of the present invention containing simultaneously, it is prepared using a non-aqueous electrolyte solution containing one of these compounds or not containing both of these compounds Compared with the non-aqueous electrolyte secondary battery, the capacity after the high-temperature cycle test is increased.

On the other hand, for example, when the fluorine-containing ethylene carbonate derivative is used alone, it has been shown that the capacity after the cycle is not increased, and the first time after the cycle is obtained by using a specific compound defined in the present invention in combination. The effect of increasing the capacity is not expected from here.
Further, for example, it has been shown that the fluorine-containing ethylene carbonate derivative alone does not contribute to an increase in the initial capacity, but surprisingly, the effect of suppressing the decrease in the initial capacity by the simultaneous use of the present invention. It is shown.

<Examples 2-1 to 2-3, Comparative Examples 2-1 to 2-5>
[Preparation of non-aqueous electrolyte secondary battery]
<Production of negative electrode>
98 parts by mass of graphite powder, 1 part by mass of carbon black as a conductive agent, and 6 parts by mass of polyvinylidene fluoride (PVdF) as a binder were mixed and slurried in N-methyl-2-pyrrolidone. It was uniformly applied to a copper foil having a thickness of 12 μm, dried, and roll-pressed to obtain a negative electrode.

<Manufacture of non-aqueous electrolyte secondary battery>
A positive electrode, a negative electrode, and a polyolefin separator to be described later were laminated in the order of the negative electrode, the separator, and the positive electrode. The battery element thus obtained was wrapped in an aluminum laminate film, injected with an electrolyte solution described later, and then vacuum sealed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of non-aqueous electrolyte secondary battery]
Initial charge / discharge In a constant temperature bath of 25 ° C., sheet-like non-aqueous electrolyte secondary battery is 0.1 C (the rated capacity with a discharge capacity of 1 hour rate is 1 C. The current value is 1 C. The same applies hereinafter. )) To a constant current-constant voltage up to 4.2V, and then discharged to 3.0V at 0.1C. Subsequently, the battery was charged at a constant current-constant voltage to 0.3 V at 0.33 C, and then discharged to 3.0 V at 0.33 C. This was carried out for 2 cycles for a total of 3 cycles to stabilize the non-aqueous electrolyte secondary battery. The last discharge capacity was defined as “initial capacity”.

-High-temperature cycle test In a constant temperature bath at 55 ° C, a constant current-constant voltage charge at 1 C to 4.2 V was performed, and a process of discharging to 2.7 V at a constant current of 1 C was performed as 30 cycles. The capacity at the 30th cycle was defined as “capacity after cycle”.
[Example 2-1]
<Preparation of positive electrode>
72 parts by mass of lithium manganate (Li _1.1 Mn _1.9 Al _0.1 O ₄ ) as the first positive electrode active material, lithium nickel manganese cobalt composite oxide (Li _{1. 15} Ni _0.45 Mn _0.45 Co _0.10 O ₂ ), 18 parts by mass, 5 parts by mass of carbon black as a conductive agent, 5 parts by mass of polyvinylidene fluoride (PVdF) as a binder, N -Mixed and slurried in methyl-2-pyrrolidone, uniformly applied to a 15 μm thick aluminum foil, dried, and then roll pressed to form a positive electrode (hereinafter abbreviated as LMO + NMC).

<Adjustment of electrolyte>
In a dry argon atmosphere, 1 mol / L (as a concentration in the non-aqueous electrolyte) of LiPF ₆ that was sufficiently dried was dissolved in a mixture of ethylene carbonate and diethyl carbonate (volume ratio 3: 7). Dried 1,6-diisocyanatohexane (DIH) with 0.5% by mass (as a concentration in the non-aqueous electrolyte) and sufficiently dried 4-fluoro-1,3-dioxolan-2-one ( FEC) was dissolved in an amount of 1.5% by mass (as a concentration in the non-aqueous electrolyte solution) to prepare a non-aqueous electrolyte solution. A battery was prepared by the above-described method using this nonaqueous electrolytic solution, and the above evaluation was performed.

[Example 2-2]
A battery was prepared in the same manner as in Example 2-1, except that 2% by mass of -fluoro-1,3-dioxolan-2-one (FEC) was dissolved in a nonaqueous electrolytic solution, and the above evaluation was performed.
[Example 2-3]
Except that 0.2 mass% of 1,6-diisocyanatohexane (DIH) was dissolved in non-aqueous electrolyte solution and 2 mass% of 4-fluoro-1,3-dioxolan-2-one (FEC) was dissolved. A battery was prepared in the same manner as in Example 2-1, and the above evaluation was performed.

[Comparative Example 2-1]
A battery was prepared in the same manner as in Example 2-1, except that 1,6-diisocyanatohexane (DIH) and 4-fluoro-1,3-dioxolan-2-one (FEC) were not dissolved in the nonaqueous electrolytic solution. Prepared and conducted the above evaluation.
[Comparative Example 2-2]
A battery was prepared in the same manner as in Example 2-1, except that 4-fluoro-1,3-dioxolan-2-one (FEC) was not dissolved in the nonaqueous electrolytic solution, and the above evaluation was performed.

[Comparative Example 2-3]
Example 2 except that 1,6-diisocyanatohexane (DIH) was not dissolved in the nonaqueous electrolytic solution, but 1% by mass of 4-fluoro-1,3-dioxolan-2-one (FEC) was dissolved. A battery was prepared in the same manner as in Example 1, and the above evaluation was performed.
[Comparative Example 2-4]
A battery was prepared in the same manner as in Example 2-1, except that 1% by mass of vinylene carbonate (VC) was dissolved in a non-aqueous electrolyte instead of 4-fluoro-1,3-dioxolan-2-one (FEC). The above evaluation was performed.

Table 2 below shows the initial capacity and the post-cycle capacity normalized by dividing by the capacity of Comparative Example 2-1.

As is apparent from Table 2, using a positive electrode having a lithium manganese composite oxide having a spinel structure as a main component of an active material, a “specific CN compound” and a fluorine-containing ethylene carbonate derivative are added in a non-aqueous electrolyte solution. In the non-aqueous electrolyte secondary battery of the present invention prepared using the non-aqueous electrolyte solution contained at the same time, it was prepared using a non-aqueous electrolyte solution containing one of these compounds or not containing both of these compounds. Compared with the non-aqueous electrolyte secondary battery, an increase in the post-cycle capacity can be confirmed although there is almost no decrease in the initial capacity.

  Further, for example, it has been shown that the fluorine-containing ethylene carbonate derivative does not increase the post-cycle capacity when used alone, but surprisingly, the specific compound defined in the present invention and the specific positive electrode are combined. The effect of increasing the post-cycle capacity by using it is shown.

<Examples 3-1 to 3-2 and Comparative Example 3-1>
[Example 3-1]
[Preparation of non-aqueous electrolyte]
Under a dry argon atmosphere,
FEC 6.5% by mass, VC 1.0% by mass, 2,2,4-trimethylhexahexene as a content in a non-aqueous electrolyte solution in a mixture of ethylene carbonate and dimethyl carbonate (volume ratio 26.3: 73.7) Mix 0.15% by weight of methylene diisocyanate and 0.15% by weight of 2,4,4-trimethylhexamethylene diisocyanate, and then dissolve well-dried LiPF ₆ at a rate of 1.0 mol / liter. An electrolyte solution was prepared.

[Production of negative electrode]
Aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose 1% by mass) and aqueous styrene butadiene rubber as thickener and binder, respectively, on 100 parts by mass of amorphous coated graphite powder as negative electrode active material Dispersion (styrene butadiene rubber concentration 50 mass%) was added and mixed with a disperser to form a slurry. After this slurry was uniformly applied to one side of a 12 μm thick copper foil and dried,
The negative electrode was pressed. In addition, in the negative electrode after drying, it produced so that it might become a mass ratio of amorphous covering graphite: Carboxymethylcellulose sodium: styrene butadiene rubber = 100: 1: 1.

[Production of positive electrode]
97% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 1.5% by mass of acetylene black as a conductive material, and 1.5% by mass of polyvinylidene fluoride (PVdF) as a binder, N-methylpyrrolidone In a solvent, the mixture was slurried by mixing with a disperser. This was uniformly applied to both sides of a 21 μm thick aluminum foil, dried, and then pressed to obtain a positive electrode.

[Production of secondary battery]
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 a laminate film in which both surfaces of aluminum (thickness 40 μm) are coated with a resin layer while projecting positive and negative terminals, a non-aqueous electrolyte solution is injected into the bag, Vacuum sealing was performed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Initial capacity evaluation]
A non-aqueous electrolyte secondary battery is charged with being sandwiched between glass plates and pressurized at 25 ° C. with a current corresponding to 0.05 C for 6 hours, and then at a constant current up to 3.0 V at 0.2 C. Discharge was performed. After that, constant current-constant voltage charge (hereinafter referred to as “CC-CV charge” where appropriate) (0.05C cut) to 4.1V with a current corresponding to 0.2C, and then discharged to 3V with a constant current of 0.2C. did. Furthermore, after CC-CV charge (0.05C cut) to 4.33V with a current corresponding to 0.2C, the operation of discharging to 3V at 0.2C was repeated three times, and the third discharge capacity was set as the initial capacity. .
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.

[Evaluation of discharge storage characteristics]
After the initial capacity evaluation, the non-aqueous electrolyte secondary battery was subjected to CCCV discharge (0.005 C cut) to 3.0 V at 0.2 C at 25 ° C., and then at 60 ° C. for 168 hours. Saved. After sufficiently cooling the battery, the open circuit voltage (OCV) of the battery was measured, and the difference between the OCV before storage and after storage was defined as the OCV drop during discharge storage.
Using the non-aqueous electrolyte secondary battery produced above, initial capacity evaluation and discharge storage characteristic evaluation were performed. The evaluation results are shown in Table 3.

[Example 3-2]
In the electrolytic solution of Example 3-1, except that 0.35% by mass of 2,2,4-trimethylhexamethylene diisocyanate and 0.35% by mass of 2,4,4-trimethylhexamethylene diisocyanate were used, Similarly, non-aqueous electrolyte batteries were prepared, and initial capacity evaluation and discharge storage characteristic evaluation were performed. The evaluation results are shown in Table 3.

[Comparative Example 3-1]
In the electrolytic solution of Example 3-1, a non-aqueous system was used in the same manner as in Example 1 except that an electrolytic solution not containing 2,2,4-trimethylhexamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate was used. An electrolyte battery was prepared, and initial capacity evaluation and discharge storage characteristic evaluation were performed. The evaluation results are shown in Table 3.

As is apparent from Table 3, this book was prepared by using a non-aqueous electrolyte containing a “specific CN compound”, a fluorine-containing ethylene carbonate derivative and a carbonate having a carbon-carbon unsaturated bond at the same time in the non-aqueous electrolyte. In the non-aqueous electrolyte secondary battery of the invention, an improvement in the initial capacity is seen when compared with a non-aqueous electrolyte secondary battery prepared using a non-aqueous electrolyte containing no “specific CN compound”, and the discharge The decrease in OCV during storage can be suppressed.

According to the non-aqueous electrolyte solution of the present invention, even when a large current is output, a non-aqueous electrolyte secondary battery having a large capacity can be manufactured. Therefore, an electronic device in which the non-aqueous electrolyte secondary battery is used Etc., and can be suitably used in all fields.
The application of the non-aqueous electrolyte solution and the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and can be used for various known applications. Specific examples of applications include laptop computers, electronic book players, mobile phones, mobile faxes, mobile copy, mobile printers, mobile audio players, small video cameras, LCD TVs, handy cleaners, transceivers, electronic notebooks, calculators, and memories. Cards, portable tape recorders, radios, backup power supplies, automobiles, motorcycles, motorbikes, bicycles, lighting equipment, toys, game machines, watches, electric tools, strobes, cameras, etc.

Claims (11)

In a non-aqueous electrolyte solution containing a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent,
(A) at least one compound selected from the group consisting of a carbonate having a carbon-carbon unsaturated bond, a compound represented by the following general formula (1),
(B) a fluorine-containing ethylene carbonate derivative;
(C) a compound represented by the following general formula ( 3 ),
X-R ⁴ -X (3)
(In formula (3), R ⁴ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms, and X is an isocyanato group.)
Viewing including the door,
The carbonate having a carbon-carbon unsaturated bond is at least one compound selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate and ethynyl ethylene carbonate;
The fluorine-containing ethylene carbonate derivative is 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one;
A total of at least one compound selected from the group consisting of a carbonate having a carbon-carbon unsaturated bond and a compound represented by the general formula (1) is 0.001 in a non-aqueous electrolyte.
Contained in an amount of 10% by mass or more,
The fluorine-containing ethylene carbonate derivative is contained in the nonaqueous electrolytic solution in an amount of 0.001% by mass to 10% by mass,
Containing 0.001% by mass or more and 10% by mass or less of the compound represented by the general formula (3) in the non-aqueous electrolyte solution;
A non-aqueous electrolyte characterized by that.

(In the above formula (1), M -O - a Oh Ri, ^{R 1} _{is, -CH 2 -CH 2 -, -} CH 2 -CH 2 -CH 2 -, - CH = CH -, - CH = C (CH ₃ ) —, —CH ₂ —C (═CH ₂ ) — and a hydrocarbon group selected from the group consisting of hydrocarbon groups represented by the following formula (4) .

The compound represented by the general formula ( 3 ) is 1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1 ] Heptane-2,5-diylbis (methyl = isocyanate), or bicyclo [2.2.1] heptane-2,6-diylbis (methyl = isocyanate), 2,4,4-trimethylhexamethylene diisocyanate and 2 The nonaqueous electrolytic solution according to claim 1, which is a compound selected from 1,2,4-trimethylhexamethylene diisocyanate. The non-aqueous electrolyte solution according to claim 1 or 2, wherein the compound represented by the general formula (1) is succinic anhydride or maleic anhydride. The carbon - carbonate having a carbon-carbon unsaturated bond is a non-aqueous electrolyte solution according to any one of claims 1 to 3, characterized in that the vinylene carbonate Natick bets. A total of at least one compound selected from the group consisting of the carbonate having a carbon-carbon unsaturated bond and the compound represented by the general formula (1) is added to the nonaqueous electrolyte solution in an amount of 0.
The non-aqueous electrolyte solution according to any one of claims 1 to 4 , wherein the non-aqueous electrolyte solution is contained in an amount of 01 % by mass to 3 % by mass. Wherein the fluorine-containing ethylene carbonate derivatives, non-aqueous electrolyte solution according to any one of claims 1, characterized in that it contains 8% by mass or less than 0.01 wt% in the non-aqueous electrolyte solution 5. A non-aqueous electrolyte secondary battery comprising at least a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution comprises: A nonaqueous electrolyte secondary battery, which is the nonaqueous electrolyte solution according to any one of items 6 to 6 . Non-aqueous electrolysis comprising at least a positive electrode capable of inserting and extracting lithium ions, a negative electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolytic solution including a non-aqueous solvent and an electrolyte dissolved in the non-aqueous solvent In the liquid secondary battery, the positive electrode contains a lithium manganese composite oxide having a spinel structure, and the non-aqueous electrolyte solution includes:
(A) a fluorine-containing ethylene carbonate derivative;
(B) a compound represented by the following general formula ( 3 ),
X-R ⁴ -X (3)
(In formula (3), R ⁴ is a hydrocarbon group which may have a hetero element having 15 or less carbon atoms, and X is an isocyanato group.)
Including
The fluorine-containing ethylene carbonate derivative is 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one;
Fluorine-containing ethylene carbonate derivative in 0.001% by mass or more in a non-aqueous electrolyte solution
Containing less than
A non-aqueous electrolyte secondary battery comprising 0.001% by mass or more and 10% by mass or less of a compound represented by the general formula (3) in a non-aqueous electrolyte. The non-aqueous electrolyte secondary battery according to claim 8 , wherein the positive electrode containing the lithium manganese composite oxide further contains a lithium nickel composite oxide having a layered structure. The compound represented by the general formula (3) is 1,6-diisocyanatohexane, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4′-diisocyanate, bicyclo [2.2.1. ] Heptane-2,5-diylbis (methyl = isocyanate), or bicyclo [2.2.1] heptane-2,6-diylbis (methyl = isocyanate), 2,4,4-trimethylhexamethylene diisocyanate and 2 The non-aqueous electrolyte secondary battery according to claim 8 , wherein the non-aqueous electrolyte secondary battery is a compound selected from 1,2,4-trimethylhexamethylene diisocyanate. Said fluorine-containing ethylene carbonate derivatives, non-aqueous electrolyte secondary according to any one of claims 8 to 10 in the non-aqueous electrolytic solution characterized by containing more than 8 wt% 0.01 wt% battery.