JP5782718B2 - Non-aqueous electrolyte and non-aqueous electrolyte battery using the same - Google Patents

Description

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

With the rapid progress of electronic devices, the demand for higher capacity for secondary batteries is increasing, and lithium ion secondary batteries with higher energy density compared to nickel-cadmium batteries and nickel-hydrogen batteries are widely used. Also actively researched.
The electrolyte used for a nonaqueous electrolyte battery is usually composed mainly of an electrolyte and a nonaqueous solvent. As an electrolyte for a lithium ion secondary battery, an electrolyte such as LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , a high dielectric constant solvent such as ethylene carbonate, propylene carbonate, γ-butyrolactone, dimethyl carbonate, A nonaqueous electrolytic solution dissolved in a mixed solvent with a low viscosity solvent such as diethyl carbonate or ethyl methyl carbonate is used.

In such a lithium ion secondary battery, when charging and discharging are repeated, the capacity is reduced, and gas is generated when exposed to a high temperature state. In order to improve it, various studies have been made on nonaqueous solvents and electrolytes.
In JP-A-9-199172, it has been reported that the cycle characteristics are improved by using a nonaqueous electrolytic solution containing an oxalate ester.

JP-A-9-199172

However, in the invention of Patent Document 1, since the compound containing only one divalent group represented by the general formula (1) of this patent is used in the molecule, the effect of improving the cycle characteristics is satisfactory. However, the effect of suppressing gas generation when exposed to high temperature conditions was not expected.
In the non-aqueous electrolyte secondary battery, the present invention suppresses gas generation during high-temperature storage in a charged state, and suppresses capacity reduction when repeated charge and discharge, It is an object of the present invention to provide a secondary battery using this non-aqueous electrolyte.

As a result of various investigations to achieve the above object, the present inventors have found that the above-mentioned problems can be solved by containing the following compounds in the electrolytic solution, and the present invention has been completed. It was.
That is, the gist of the present invention is as follows.
A nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent contains a compound (A) having two or more divalent groups represented by the following general formula (1) in the molecule (Claim 1).

The compound (A) is a chain compound (Claim 2).
The compound (A) is a compound represented by the following general formula (2) (Claim 3).

(Wherein R ¹ and R ³ each independently represents a monovalent group selected from the group consisting of —OR ⁴ , —SR ⁵ and —NR ⁶ R ⁷ groups. R ⁴ and R ⁵ represent a halogen atom. R ⁶ and R ⁷ each represents a hydrocarbon group or a hydrogen atom which may have a halogen atom, wherein R ² represents —OR ⁸ O— or —SR ^9. Represents a divalent group selected from the group consisting of S—, —NR ¹⁰ —R ¹¹ —NR ¹² — groups, wherein R ⁸ , R ⁹ and R ¹¹ may have a hetero atom or a halogen atom; A valent hydrocarbon group, R ¹⁰ and R ¹² each represents a hydrocarbon group or a hydrogen atom optionally having a halogen atom.)
The compound (A) is contained in a proportion of 0.001 % by mass or more and 10% by mass or less with respect to the entire nonaqueous electrolytic solution (claim 4).

A non-aqueous electrolyte battery including a negative electrode, a positive electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 4 (claim 5).
A compound represented by the general formula (3) (Claim 6).

(Wherein R ¹ and R ³ each independently represents a monovalent group selected from the group consisting of —OR ⁴ , —SR ⁵ and —NR ⁶ R ⁷ groups. R ⁴ and R ⁵ represent a halogen atom. R ⁶ and R ⁷ each represents a hydrocarbon group or a hydrogen atom which may have a halogen atom, wherein R ² represents —OR ⁸ O— or —SR ^9. Represents a divalent group selected from the group consisting of S—, —NR ¹⁰ —R ¹¹ —NR ¹² — groups, wherein R ⁸ , R ⁹ and R ¹¹ may have a hetero atom or a halogen atom; A valent hydrocarbon group, R ¹⁰ and R ¹² each represents a hydrocarbon group or a hydrogen atom optionally having a halogen atom.)

By using the non-aqueous electrolyte of the present invention, a non-aqueous electrolyte battery excellent in the effect of suppressing gas generation during high-temperature storage in a charged state and suppressing capacity reduction when repeatedly charged and discharged Can be obtained.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the description described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents unless it exceeds the gist of the claims.
[1. (Nonaqueous electrolyte)
The nonaqueous electrolytic solution of the present invention contains an electrolyte and a nonaqueous solvent that dissolves the electrolyte, as well as a general nonaqueous electrolytic solution. Further, the divalent group represented by the general formula (1) is a molecule. It contains the compound (A) having 2 or more in the inside.

[1-1. Electrolytes〕
There is no restriction | limiting in the electrolyte used for the non-aqueous electrolyte of this invention, A well-known thing can be arbitrarily employ | adopted if it is used as an electrolyte for the target non-aqueous electrolyte secondary battery. When the nonaqueous electrolytic solution of the present invention is used for a lithium secondary battery, a lithium salt is usually used as an electrolyte.

Specific examples of the electrolyte include LiClO _4, LiAsF ₆ , LiPF ₆ , Li ₂ CO ₃ , L
Inorganic lithium salts such as iBF ₄ ; LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,3-hexafluoropropane disulfonylimide, lithium cyclic 1, 2-tetrafluoroethanedisulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , Li
PF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂
Fluorinated organolithium salts such as (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ; lithium bis (oxalato) borate, lithium tris (oxalato) phos Examples thereof include lithium salts of dicarboxylic acid complexes such as fete, lithium difluorooxalatoborate, and lithium difluorobis (oxalato) phosphate.

Of these, LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂ , and LiN (C ₂ F ₅ SO ₂ ) ₂ are preferable from the viewpoint of stability in the battery, and LiPF ₆ and LiBF ₄ are particularly preferable. .
Moreover, electrolyte may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. In particular, when two types of specific inorganic lithium salts are used in combination, or when inorganic lithium salts and fluorine-containing organic lithium salts are used in combination, gas generation during trickle charging is suppressed, and deterioration after high-temperature storage is suppressed. Therefore, it 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, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) _2, etc. It is preferable to use in combination with a fluorine-containing organic lithium salt.

Furthermore, when LiPF ₆ and LiBF ₄ are used in combination, it is preferable that LiBF ₄ is usually contained at a ratio of 0.01% by mass or more and 50% by mass or less with respect to the entire electrolyte. The ratio is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, preferably 20% by mass or less, more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably. Is 3% by mass or less. When the ratio is within the above range, a desired effect can be more easily obtained, the degree of dissociation of LiBF ₄ does not become too low, and the increase in resistance of the nonaqueous electrolytic solution can be suppressed.

On the other hand, inorganic lithium salts such as LiPF ₆ and LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF _{3
SO 2) 2, LiN (C} 2 F 5 SO 2) When used in combination with a fluorine-containing organic lithium salt of _2, etc., the proportion of the inorganic lithium salt in the whole electrolyte is usually 70 mass% or more, less 99% A range is desirable.
The concentration of the lithium salt in the nonaqueous electrolytic solution of the present invention is arbitrary as long as the gist of the present invention is not impaired, but is usually 0.5 mol / L or more, preferably 0.6 mol / L or more, more preferably 0.8. 8 mol / L or more, more preferably 1.0 mol / L or more, particularly preferably 1.1 mol / L or more, and most preferably 1.2 mol / L or more. Moreover, it is 3 mol / L or less normally, Preferably it is 2 mol / L or less, More preferably, it is 1.8 mol / L or less, More preferably, it is the range of 1.6 mol / L or less. When this concentration is within the above range, the viscosity of the non-aqueous electrolyte does not become too high, and a high electrical conductivity can be provided. Therefore, the non-aqueous electrolyte battery using the non-aqueous electrolyte of the present invention Performance can be further improved.

[1-2. Nonaqueous solvent)
The non-aqueous solvent contained in the non-aqueous electrolyte of the present invention can be appropriately selected from those conventionally known as solvents for non-aqueous electrolytes. In addition, a non-aqueous solvent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
Examples of commonly used non-aqueous solvents include cyclic carbonates, chain carbonates, chain and cyclic carboxylic acid esters, chain and cyclic ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, and the like.

Examples of the cyclic carbonate include alkylene carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate, and fluorinated alkylene carbonates such as fluoroethylene carbonate. The alkylene carbonates usually have 3 to 6 carbon atoms.
Among these, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate are preferable in that the electrolyte is easy to dissolve because of a high dielectric constant, and cycle characteristics are good when a non-aqueous electrolyte secondary battery is used. preferable.

Examples of the chain carbonate include dialkyl carbonates such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate. Are preferably 1 or more and 5 or less, and particularly preferably 1 or more and 4 or less. Further, a part of hydrogen of the alkyl group may be substituted with fluorine.
Among these, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable from the viewpoint of improving battery characteristics.

Examples of chain carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, t-butyl acetate, amyl acetate, methyl propionate, ethyl propionate, propionic acid Propyl, isopropyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl valerate, ethyl valerate, etc. and compounds in which part of hydrogen of these compounds such as propyl trifluoroacetate and butyl trifluoroacetate is substituted with fluorine, etc. The total carbon number of the chain carboxylic acid esters is usually 3 or more and 10 or less, preferably 4 or more and 7 or less. Among these, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, amyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, and methyl valerate are more preferable.

Examples of the cyclic carboxylic acid ester include γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Among these, γ-butyrolactone is more preferable.
Furthermore, examples of the chain ether include dimethoxymethane, dimethoxyethane, diethoxymethane, diethoxyethane, ethoxymethoxymethane, ethoxymethoxyethane and the like. Among these, dimethoxyethane and diethoxyethane are more preferable.

Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran and the like.
Furthermore, the type of the phosphorus-containing organic solvent is not particularly limited. Examples of commonly used organic solvents include phosphate esters such as trimethyl phosphate, triethyl phosphate, and triphenyl phosphate;
Phosphites such as trimethyl phosphite, triethyl phosphite, triphenyl phosphite; phosphine oxides such as trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, and phosphazenes.

Examples of the sulfur-containing organic solvent include ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene and the like.
Among the above non-aqueous solvents, it is preferable to use at least one selected from cyclic carbonates such as ethylene carbonate, propylene carbonate, and fluoroethylene carbonate, and these and chain carbonates such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. It is preferable to use at least one selected from the viewpoints of the viscosity and electric conductivity of the electrolytic solution.

  Thus, when using a cyclic carbonate and a chain carbonate together as a non-aqueous solvent, the preferred content of the chain carbonate in the non-aqueous solvent in the non-aqueous electrolyte of the present invention is usually 20% by volume or more, Preferably it is 40 volume% or more, and is 95 volume% or less normally, Preferably it is 90 volume% or less. On the other hand, the suitable content of the cyclic carbonate in the non-aqueous solvent in the non-aqueous electrolyte of the present invention is usually 5% by volume or more, preferably 10% by volume or more, and usually 80% by volume or less, preferably 60%. % By volume or less. When the proportion of the chain carbonate is within the above range, the viscosity of the electrolytic solution becomes appropriate, and the degree of dissociation of the lithium salt that is the electrolyte does not decrease, so that the electrical conductivity is hardly lowered.

In the present specification, the capacity of the non-aqueous solvent is a measured value at 25 ° C., but a measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.
[1-3. Compound (A)]
A nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent contains a compound (A) having two or more divalent groups represented by the following general formula (1) in the molecule.

  In the present invention, by having two or more divalent groups represented by the above general formula (1) in the molecule as the compound A, it is possible to suppress a decrease in capacity when charging / discharging is repeated, It suppresses gas generation during high-temperature storage, and other partial structures are not particularly limited, but examples thereof include chain compounds and cyclic compounds having two or more divalent groups represented by (1) in the molecule. . Among these, a chain compound is particularly preferable.

  Among the chain compounds, which are the compound (A), the following compound (2) shown in claim 3 is particularly preferable.

(Wherein R ¹ and R ³ each independently represents a monovalent group selected from the group consisting of —OR ⁴ , —SR ⁵ and —NR ⁶ R ⁷ groups. R ⁴ and R ⁵ represent a halogen atom. R ⁶ and R ⁷ each represents a hydrocarbon group or a hydrogen atom which may have a halogen atom, wherein R ² represents —OR ⁸ O— or —SR ^9. Represents a divalent group selected from the group consisting of S—, —NR ¹⁰ —R ¹¹ —NR ¹² — groups, wherein R ⁸ , R ⁹ and R ¹¹ may have a hetero atom or a halogen atom; A valent hydrocarbon group, R ¹⁰ and R ¹² each represents a hydrocarbon group or a hydrogen atom optionally having a halogen atom.)
R ⁴ and R ⁵ are preferably hydrocarbon groups having 1 to 10 carbon atoms, more preferably hydrocarbon groups having 1 to 5 carbon atoms, and hydrocarbon groups having 1 to 3 carbon atoms. It is particularly preferred that R ⁶ and R ⁷ are preferably a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, more preferably a hydrocarbon group having 1 to 5 carbon atoms, and a hydrocarbon having 1 to 3 carbon atoms. Particularly preferred is a group. R ⁸ , R ⁹ , and R ¹¹ are preferably hydrocarbon groups that may have 1 to 30 carbon atoms, and carbon atoms that may have 1 to 20 carbon atoms. More preferably, it is a hydrogen group. R ¹⁰ and R ¹² are preferably a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, more preferably a hydrocarbon group having 1 to 5 carbon atoms or a hydrogen atom, and a carbon atom having 1 to 3 carbon atoms. A hydrogen group or a hydrogen atom is particularly preferable. Specific examples of (2) include the following.

Among the above, (2-B), (2-D), (2-F), (2-I), (2-K), (2-L), (2-M),
(2-O), (2-P), (2-Q), (2-S), (2-T), and (2-U) are preferable from the viewpoint of improving battery characteristics and facilitating production. .
Although content of a compound (A) is not specifically limited, 0.001 mass% or more and 10 mass% or less are respectively preferable with respect to a non-aqueous electrolyte. The content is more preferably 0.01% by mass or more, and particularly preferably 0.1% by mass or more. On the other hand, 7 mass% or less is still more preferable, and 5 mass% or less is especially preferable. When the content of the compound (A) is within the above range, the resistance of the nonaqueous electrolytic solution is difficult to increase, and thus the effect of the present invention tends to be exhibited. Although the compound represented by a compound (A) may be 1 type, or may use multiple types together, when using multiple types together, the said content represents the total amount of multiple types.
When the electrolytic solution containing the compound (A) is used, cycle characteristics are improved. Although the detailed mechanism is not clarified, it is considered that the effect of the present invention can be obtained by forming a good film on the electrode.

[1-4. Other 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 as an additive.
In addition, 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.
Specific examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; Partial fluorides of the aromatic compounds such as fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorine-containing compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroaniol Anisole compounds; and the like.

In addition, these overcharge inhibitors may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
When the non-aqueous electrolyte of the present invention contains an overcharge inhibitor, its concentration is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by mass or more based on the whole non-aqueous electrolyte, It is desirable to set it as the range of 5 mass% or less. By including an overcharge inhibitor in the non-aqueous electrolyte, it is possible to suppress rupture and ignition of the non-aqueous electrolyte secondary battery due to overcharge, and the safety of the non-aqueous electrolyte secondary battery is improved. preferable.

On the other hand, as a specific example of the auxiliary agent for improving capacity maintenance characteristics and cycle characteristics after high temperature storage,
Vinylene carbonate compounds such as vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, fluoro vinylene carbonate, trifluoromethyl vinylene carbonate,
Vinyl ethylene carbonate compounds such as vinyl ethylene carbonate, 4-methyl-4-vinyl ethylene carbonate, 5-methyl-4-vinyl ethylene carbonate, 4,4-divinyl ethylene carbonate, 4,5-divinyl ethylene carbonate;
4-ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-4-ethynylethylene carbonate, 4-ethynyl-5-methylethylene carbonate, and the like,
Among these, there may be mentioned methylene ethylene carbonate compounds such as 4,4-dimethyl-5-methylene ethylene carbonate and 4-methylene ethylene carbonate. Among these, vinylene carbonate, vinyl ethylene carbonate, 4-methyl-4-vinyl ethylene carbonate or 4, 5-Divinylethylene carbonate is preferable from the viewpoint of improving cycle characteristics and capacity maintenance characteristics after high-temperature storage. Among them, vinylene carbonate or vinylethylene carbonate is more preferable, and vinylene carbonate is particularly preferable. These may be used alone or in combination of two or more.

When using 2 or more types together, it is preferable to use together vinylene carbonate and vinyl ethylene carbonate.
When the cyclic carbonate compound having a carbon-carbon unsaturated bond is contained, the proportion in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly preferably 0.3% by mass. % Or more, most preferably 0.5% by mass or more. Moreover, the upper limit is 10 mass% normally, Preferably it is 8 mass%, Most preferably, it is 6 mass%. When the cyclic carbonate compound having a carbon-carbon unsaturated bond is within the above range, it is difficult to increase the amount of gas generated during high-temperature storage, and the effect of improving battery cycle characteristics and capacity maintenance characteristics after high-temperature storage is sufficient. Can be demonstrated.

Examples of the cyclic carbonate having a halogen atom include fluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,4,5-trifluoroethylene carbonate, 4,4,5,5- Tetrafluoroethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4,4,5-trifluoro-5-methylethylene Examples thereof include carbonate and trifluoromethylethylene carbonate. Of these, fluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4-fluoro-5-methylethylene carbonate are preferable from the viewpoint of improving cycle characteristics and high-temperature storage characteristics. These may be used alone or in combination of two or more.

When the non-aqueous electrolyte contains a cyclic carbonate compound having a fluorine atom, the proportion in the non-aqueous electrolyte is usually 0.001% by mass or more, preferably 0.1% by mass or more, particularly preferably 0.8. It is 3% by mass or more, most preferably 0.5% by mass or more, and is usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less.
However, fluoroethylene carbonate may be used as a solvent as described in the section of 1-2 nonaqueous solvent, and in that case, the content is not limited to the above.

The monofluorophosphate or difluorophosphate is not particularly limited as a counter cation of monofluorophosphate and difluorophosphate, but lithium, sodium, potassium, magnesium, calcium, and N ⁺ Examples include ammonium represented by R ⁴ R ⁵ R ⁶ R ⁷ (wherein R ^{4 to} R ⁷ each independently represents a hydrogen atom or an organic group having 1 to 12 carbon atoms).

Although it does not specifically limit as a C1-C12 organic group represented by R < ⁴ > -R < ⁷ > of the said ammonium, For example, it is substituted by the alkyl group, the halogen atom, or the alkyl group which may be substituted by the halogen atom. Examples thereof include an cycloalkyl group which may be substituted, an aryl group which may be substituted with a halogen atom or an alkyl group, and a nitrogen atom-containing heterocyclic group which may have a substituent. Among these, as R ^{4 to} R ⁷ , a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group is preferable.

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

These may be used alone or in combination of two or more.
When the non-aqueous electrolyte contains a monofluorophosphate and / or difluorophosphate, the proportion in the non-aqueous electrolyte is usually 0.001% by mass or more, preferably 0.01% by mass or more, Especially preferably, it is 0.1 mass% or more, Most preferably, it is 0.2 mass% or more, Usually, 5 mass% or less, Preferably it is 3 mass% or less, Most preferably, it is 2 mass% or less.

  In addition, when the monofluorophosphate and difluorophosphate are actually used for producing a secondary battery as a non-aqueous electrolyte, the content of the monofluorophosphate and the difluorophosphate is not limited even if the battery is disassembled and the non-aqueous electrolyte is extracted again. Is often significantly reduced. Accordingly, those in which at least one monofluorophosphate and / or difluorophosphate can be detected from the non-aqueous electrolyte extracted from the battery are detected in the non-aqueous electrolyte at a predetermined ratio defined in the present invention. It is considered to be a non-aqueous electrolyte containing.

As nitrile compounds, acetonitrile, propionitrile, butyronitrile, valeronitrile, hexane nitrile, heptane nitrile, octane nitrile, nonane nitrile, decane nitrile (lauronitrile), tridecane nitrile, tetradecane nitrile (myristonitrile) ), Mononitriles such as hexadecane nitrile, pentadecane nitrile, heptadecane nitrile, octadecane nitrile (steanonitrile), nonadecane nitrile, icosane nitrile; malononitrile, succinonitrile,
Glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile,
Methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, trimethylsuccinonitrile, tetramethylsuccinonitrile, 3,3'-oxydipropionitrile, 3,3'-thio Dipropionitrile, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′-(ethylenedithio) dipropionitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetri Examples thereof include dinitriles such as carbonitrile, 1,2,3-tris (2-cyanoethoxy) propane, tris (2-cyanoethyl) amine, and among these, lauronitrile, succinonitrile, glutaronitrile, adiponitrile, and pimelonitrile. Is preferred.

These may be used alone or in combination of two or more.
When the non-aqueous electrolyte contains a nitrile compound, the proportion in the non-aqueous electrolyte is usually 0.001% by mass or more, preferably 0.01% by mass or more, particularly preferably 0.1% by mass or more, Most preferably, it is 0.2% by mass or more, usually 10% by mass or less, preferably 5% by mass or less, and particularly preferably 2% by mass or less.

Other acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride, citraconic anhydride;
Carbonate compounds such as erythritan carbonate and spiro-bis-dimethylene carbonate;
Ethylene sulfite, 1,3-propane sultone, 1,3-propene sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, diphenyl sulfone, divinyl sulfone, methylphenyl sulfone, diethyl disulfide , Sulfur-containing compounds such as dibutyl disulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide;
1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide,
Nitrogen-containing compounds such as 4-trifluoromethylphenyl isocyanate and 1,6-diisocyanatohexane;
Hydrocarbon compounds such as heptane, octane, cycloheptane;
Fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, trifluorobenzene, benzotrifluoride, pentafluorobenzene, hexafluorobenzene;
Etc.

These auxiliary agents may be used alone or in combination of two or more in any combination and ratio.
When these auxiliaries are contained, their concentration is arbitrary as long as the effects of the present invention are not significantly impaired, but are usually in the range of 0.1% by mass or more and 5% by mass or less with respect to the whole nonaqueous electrolytic solution. It is preferable.

[1-6. Gelling agent]
The nonaqueous electrolytic solution is usually present in a liquid state when used in the lithium secondary battery of the present invention. For example, it may be gelled with a polymer to form a semi-solid electrolyte. The polymer used for the gelation is arbitrary, and examples thereof include polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, polyethylene oxide, polyacrylate, and polymethacrylate. In addition, the polymer | macromolecule used for gelatinization may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

Moreover, when using a non-aqueous electrolyte as a semi-solid electrolyte, the ratio of the non-aqueous electrolyte in the semi-solid electrolyte is arbitrary as long as the effects of the present invention are not significantly impaired. As a suitable range, the ratio of the non-aqueous electrolyte to the total amount of the semisolid electrolyte is usually 30% by mass or more, preferably 5
It is 0 mass% or more, More preferably, it is 75 mass% or more, and is 99.95 mass% or less normally, Preferably it is 99 mass% or less, More preferably, it is 98 mass% or less. When the ratio of the nonaqueous electrolytic solution is within the above range, the electrolytic solution can be easily retained and liquid leakage can be easily suppressed, and sufficient charge / discharge efficiency and capacity can be provided.

[1-7. Nonaqueous electrolyte production method]
The non-aqueous electrolytic solution of the present invention is used in the above-described non-aqueous solvent, if necessary, and the above-described electrolyte, the amide compound having a nitrogen-hydrogen bond represented by the general formula (1) of the present invention, and the like. It can be prepared by dissolving other additives.
If water is present in the non-aqueous electrolyte, electrolysis of water, reaction between water and lithium metal, hydrolysis of lithium salt, and the like may occur, which is not preferable. Therefore, when preparing the non-aqueous electrolyte, each component such as a non-aqueous solvent is preferably dehydrated in advance. Specifically, it is preferable to dehydrate until the water content is usually 50 ppm or less, particularly 20 ppm or less. The method of dehydration can be arbitrarily selected, and examples thereof include a method of heating under reduced pressure or passing through a molecular sieve.

[2. Nonaqueous electrolyte secondary battery)
The non-aqueous electrolyte secondary battery of the present invention is the same as the conventionally known non-aqueous electrolyte secondary battery except for the non-aqueous electrolyte, and is usually impregnated with the non-aqueous electrolyte of the present invention. The positive electrode and the negative electrode are laminated via a porous film (separator), and these are housed in a case (exterior body). The shape of the nonaqueous 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.

[2-1. (Nonaqueous 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 solutions with respect to the nonaqueous electrolyte solution of this invention.
[2-2. Negative electrode)
The negative electrode active material constituting the negative electrode used in the non-aqueous electrolyte secondary battery of the present invention is not particularly limited as long as it can electrochemically occlude and release lithium ions. Specific examples thereof include carbonaceous materials, alloy-based materials, lithium-containing metal composite oxide materials, and the like.

<Carbonaceous material negative electrode>
As a carbonaceous material used as a negative electrode active material of a carbonaceous material negative electrode (hereinafter sometimes referred to as “carbon negative electrode”), one selected from the following (1) to (4) is an initial irreversible capacity, high Good balance of current density charge / discharge characteristics is preferable. Moreover, the carbonaceous materials (1) to (4) may be used alone or in combination of two or more in any combination and ratio.

(1) Natural graphite
(2) Carbonaceous material obtained by heat-treating artificial carbonaceous material and artificial graphite material at least once in the range of 400 to 3200 ° C
(3) A carbonaceous material in which the negative electrode active material layer is composed of at least two types of carbonaceous materials having different crystallinity and / or has an interface in contact with the different crystalline carbonaceous materials.
(4) The carbonaceous material in which the negative electrode active material layer is composed of at least two kinds of carbonaceous materials having different orientations and / or has an interface in contact with the carbonaceous materials having different orientations.
Specific examples of the artificial carbonaceous material and the artificial graphite material of (2) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, or those obtained by oxidizing these pitches, Needle coke, pitch coke and carbon materials partially graphitized thereof, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials, and these carbides or carbonizable organic materials Examples thereof include solutions dissolved in low-molecular organic solvents such as benzene, toluene, xylene, quinoline, and n-hexane, and carbides thereof.

  In addition, as a concrete example of said carbonizable organic substance, coal-based heavy oil such as coal tar pitch from soft pitch to hard pitch, or dry distillation liquefied oil, normal pressure residual oil, direct current system of reduced pressure residual oil Decomposed petroleum heavy oil such as ethylene tar by-produced during pyrolysis of heavy oil, crude oil, naphtha, etc., and aromatic hydrocarbons such as acenaphthylene, decacyclene, anthracene, phenanthrene, and nitrogen atom-containing heterocycles such as phenazine and acridine Formula compounds, sulfur atom-containing heterocyclic compounds such as thiophene and bithiophene, polyphenylenes such as biphenyl and terphenyl, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, insolubilized products of these, nitrogen-containing polyacrylonitrile, Organic polymers such as polypyrrole, organic compounds such as sulfur-containing polythiophene, polystyrene , Cellulose, lignin, mannan, polygalacturonic acid, chitosan, natural polymers such as polysaccharides represented by saccharose, thermoplastic resins such as polyphenylene sulfide and polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, imide resin And thermosetting resins.

Any known method can be used for producing the carbon negative electrode as long as the effect of the present invention is 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.
The thickness of the negative electrode active material layer per side at the stage immediately before the non-aqueous electrolyte injection step of the battery is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 150 μm or less. 120 μm or less is preferable, and 100 μm or less is more preferable. When the thickness of the negative electrode active material is within the above range, the non-aqueous electrolyte solution can easily penetrate to the vicinity of the current collector interface, and a reduction in high current density charge / discharge characteristics can be prevented. Moreover, since the volume ratio of the current collector to the negative electrode active material does not increase extremely, the capacity of the battery does not decrease.

Further, the negative electrode active material may be roll-formed to form a sheet electrode, or may be formed into a pellet electrode by compression molding.
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used, and examples thereof include metal materials such as copper, nickel, stainless steel, and nickel-plated steel. In particular, copper is preferable.

  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.
A current collector made of a copper foil produced by a rolling method is suitable for use in a small cylindrical battery because the copper crystals are arranged in the rolling direction so that the negative electrode is hard to crack even if it is rounded sharply or rounded at an acute angle. be able to.

  Electrolytic copper foil, for example, immerses a metal drum in a non-aqueous electrolytic solution in which copper ions are dissolved, and allows current to flow while rotating it, thereby depositing copper on the surface of the drum and peeling it off Is obtained. Copper may be deposited on the surface of the rolled copper foil by an electrolytic method. One side or both sides of the copper foil may be subjected to a roughening treatment or a surface treatment (for example, a chromate treatment having a thickness of about several nm to 1 μm, a base treatment such as Ti).

The thickness of the metal thin film is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, more preferably 30 μm or less.
When the thickness of the metal film is within the above range, the coating becomes easy because it has an appropriate strength, and the shape of the electrode such as winding is not easily deformed. The metal thin film may be mesh.

The thickness ratio between the current collector and the negative electrode active material layer is not particularly limited.
The negative electrode active material layer thickness on one side) / (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, 0.4 or more is more preferable, and 1 or more is particularly preferable.
If the ratio of the thickness of the current collector to the negative electrode active material layer is within the above range, heat generation due to Joule heat of the current collector during high current density charge / discharge is difficult to occur, and the volume of the current collector relative to the negative electrode active material Since the ratio does not increase extremely, the capacity of the battery does not decrease. The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the negative electrode active material present on the current collector the density is preferably 1 g · cm ^-3 or more, more preferably 1.2 g · cm ^-3 or more, 1.3 g · cm ^-3 or more are particularly preferred, and is preferably 2 g · cm ^-3 or less, 1. 95 g · cm ⁻³ or less is more preferable, and 1.9 g · cm ⁻³ or less is still more preferable. When the density of the negative electrode active material present on the current collector is within the above range, the negative electrode active material particles are not destroyed, and an increase in initial irreversible capacity is prevented, and the current collector / negative electrode active The deterioration of the high current density charge / discharge characteristics can be prevented without causing a decrease in the permeability of the non-aqueous electrolyte to the vicinity of the substance interface. In addition, since the conductivity between the negative electrode active materials is difficult to decrease, the increase in battery resistance is prevented, and the capacity per unit volume is difficult to decrease.

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 and the solvent used during electrode production.
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 ion conductivity of alkali metal ions (particularly lithium ions); polyimides and the like. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

As the solvent for forming the slurry, any solvent can be used as long as it can dissolve or disperse the negative electrode active material, the binder (binder), and the thickener and conductive agent used as necessary. There is no particular limitation on the type, and 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, hexamethylphosphamide, 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, 0.5% by mass
The above is more preferable, 0.6% by mass or more is particularly preferable, 20% by mass or less is preferable, 15% by mass or less is more preferable, 10% by mass or less is further preferable, and 8% by mass or less is particularly preferable. When the ratio of the binder to the negative electrode active material is within the above range, it is difficult to cause a decrease in battery capacity and a decrease in strength of the electrode.

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

  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, more preferably 0.6% by mass or more, and usually 5 mass% or less, preferably 3 mass% or less, more preferably 2 mass% or less. When the ratio of the thickener to the negative electrode active material is within the above range, the coating property is excellent, and the battery capacity decreases and the negative electrode active material does not decrease without decreasing the ratio of the negative electrode active material in the negative electrode active material layer. The problem of increased resistance is less likely to occur.

<Alloy-based material negative electrode>
The negative electrode of the non-aqueous electrolyte secondary battery of the present invention is a negative electrode containing at least one atom selected from alloy materials, preferably Si and Sn, as a negative electrode active material capable of occluding and releasing metal ions (hereinafter referred to as “ It may be referred to as “alloy-based material negative electrode”).
Alloy material As the alloy material used as the negative electrode active material of the negative electrode, as long as lithium can be occluded / released, simple metals and alloys that form lithium alloys, or oxides / carbides / nitrides / silicides thereof Any compound such as sulfide or phosphide is not particularly limited, but preferably a single metal or alloy that forms a lithium alloy, Group 13 and Group 14 metal / metalloid elements of the periodic table It is preferable that there is a material containing (that is, excluding carbon), and further, a simple metal of Si and Sn (which may be referred to as “specific metal element” hereinafter), and an alloy / compound containing these atoms. preferable.

Examples of the negative electrode active material having at least one kind of atom selected from the specific metal element include a single metal of any one specific metal element, an alloy composed of two or more specific metal elements, one type, or two or more types And an alloy composed of one or more other metal elements and a compound containing one or more specific metal elements. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

Examples of compounds containing one or more specific metal elements include carbides, oxides, nitrides, silicides, sulfides, phosphides, etc. containing one or more specific metal elements. Examples include complex compounds.
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 Si and Sn, an alloy of these elements and a metal that does not operate as a negative electrode can be used. Also, for example, in Sn, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than Sn, Si, and Sn, a metal that does not operate as a negative electrode, and a non-metallic element is also used. Can do.

Among these negative electrode active materials, since the capacity per unit mass is large when a battery is formed, any one metal element of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element In particular, Si and / or Sn metals, alloys, oxides, carbides, nitrides, 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 a single metal or an alloy, the following compounds containing Si and / or Sn are also preferable because of excellent cycle characteristics.

The element ratio between Si and / or Sn and 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. Si and / or Sn oxides of 3 or less, more preferably 1.1 or less.
-Element ratio of Si and / or Sn 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. Si and / or Sn nitride of 3 or less, more preferably 1.1 or less.

-Element ratio of Si and / or Sn and 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. Si and / or Sn carbides 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.

  The alloy-based material negative electrode can be produced using any known method. Specifically, as a manufacturing method of the negative electrode, for example, a method in which a negative electrode active material added with a binder or a conductive material is roll-formed as it is to form a sheet electrode, or a compression-molded pellet electrode and And a thin film containing the above-described negative electrode active material by a method such as a coating method, a vapor deposition method, a sputtering method, or a plating method on a negative electrode current collector (hereinafter also referred to as “negative electrode current collector”) A method of forming a layer (negative electrode active material layer) is used.

Examples of the material of the negative electrode current collector include steel, copper alloy, nickel, nickel alloy, and stainless steel. Of these, copper foil is preferred from the viewpoint of easy processing into a thin film and cost.
The thickness of the negative electrode current collector is usually 1 μm or more, preferably 5 μm or more, and is usually 100 μm or less, preferably 50 μm or less. When the thickness of the negative electrode current collector is within the above range, the capacity of the entire battery is hardly reduced, and handling becomes easy.

In addition, in order to improve the binding effect with the negative electrode active material layer formed on the surface, the surface of these negative electrode current collectors is preferably subjected to a roughening treatment in advance. As the surface roughening method, the surface of the current collector is polished with a blast treatment, rolling with a rough surface roll, abrasive cloth paper with abrasive particles fixed thereto, a grindstone, an emery buff, a wire brush equipped with a steel wire, or the like. Examples thereof include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method.

  Further, in order to reduce the mass of the negative electrode current collector and improve the energy density per mass of the battery, a perforated negative electrode current collector such as an expanded metal or a punching metal can be used. In this type of negative electrode current collector, the mass can be changed to white by changing the aperture ratio. Further, when a negative electrode active material layer is formed on both surfaces of this type of negative electrode current collector, the negative electrode active material layer is further less likely to peel due to the rivet effect through the hole. However, when the aperture ratio becomes too high, the contact area between the negative electrode active material layer and the negative electrode current collector becomes small, and thus the adhesive strength may be lowered.

[2-3. (Positive electrode)
The positive electrode active material contained in the positive electrode used in the non-aqueous electrolyte secondary battery of the present invention is not particularly limited as long as it can electrochemically occlude and release lithium ions. Substances containing at least one transition metal are preferred. Specific examples include lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.

Lithium transition metal composite oxides include lithium / cobalt composite oxides such as LiCoO ₂ , lithium / nickel composite oxides such as LiNiO ₂ , and lithium / manganese composite oxides such as LiMnO ₂ , LiMn ₂ O ₄ , and Li ₂ MnO _4. And some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si And the like substituted with other metals.

As specific examples of the substituted ones, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 C
o _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 , Li Mn _1.5 Ni _0.5 O _{4 and the} like.
Lithium-containing transition metal phosphate compounds include 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, Examples include those substituted with other metals such as Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.

Furthermore, the surface of the composite oxide of transition metal and lithium described above is oxidized with metals such as Al, B, Ti, Zr, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, Ca, and Ga. It is preferable to coat with an object because the oxidation reaction of the solvent at a high voltage is suppressed. Of these, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , and MgO are particularly preferable because they have high strength and exhibit a stable coating effect.

In addition, these positive electrode active materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
The tap density of the positive electrode active material is usually 1.3 g · cm ⁻³ or more, preferably 1.5 g · cm ⁻³ or more, more preferably 1.6 g · cm ⁻³ or more, and 1.7 g · cm ^−3. more particularly preferred, and generally not more than ^{2.5g · cm -3, 2.4g · 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, it is difficult to reduce the battery capacity.

BET specific surface area of the positive electrode active material, the value of the measured specific surface area using the BET method is usually 0.2 m ² · g ^-1 or more, 0.3 m ² · g ^-1 or more preferably, 0.4 m more preferably ² · g ^-1 or more, generally not more than 4.0 m ² · g ^-1, preferably 2.5 m ² · g ^-1 or less, more preferably 1.5 m ² · g ^-1 or less. When the value of the BET specific surface area is within the above range, the battery performance is hardly lowered, and the coating property at the time of forming the positive electrode active material is improved.

Although it does not restrict | limit especially as a manufacturing method of a positive electrode active material in the range which does not exceed the summary of this invention, Several methods are mentioned, A general method is used as a manufacturing method of an inorganic compound.
Below, the structure of the positive electrode used for this invention and its preparation method are demonstrated.
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. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form are pressure-bonded to a positive electrode current collector, or these materials are liquid media A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.

  The content of the positive electrode active material in the positive electrode active material layer is usually 10% by mass or more, preferably 30% by mass or more, particularly preferably 50% by mass or more, and usually 99.9% by mass or less, preferably 99% by mass. It is as follows. When the content of the positive electrode active material in the positive electrode active material layer is within the above range, the electric capacity is difficult to decrease. In addition, sufficient strength can be provided. In addition, a positive electrode active material powder 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.

  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. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less in the positive electrode active material layer. More preferably, it is used so as to contain 15% by mass or less. When the content of the conductive material is within the above range, sufficient conductivity can be imparted, and the battery capacity is hardly reduced.
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 and the solvent used in manufacturing the electrode.

  The binder used in the coating method may be any material that can be dissolved or dispersed in the liquid medium used during electrode production. Specific examples include polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, and aromatic polyamide. Resin polymers such as cellulose and 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 hydrogen thereof Additives, 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 ratios.

The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, and usually 80% by mass or less, and 60% by mass. % Or less is preferable, 40% by mass or less is more preferable, and 10% by mass or less is particularly preferable.
When the ratio of the binder is within the above range, the positive electrode active material can be sufficiently retained, sufficient mechanical strength can be provided, and deterioration of battery performance such as cycle characteristics can be prevented. . In addition, battery capacity and conductivity are less likely to decrease.

The liquid medium for forming the slurry may be any type of solvent that can dissolve or disperse the positive electrode active material, the conductive agent, the binder, and the thickener used as necessary. There is no particular limitation, and either an aqueous solvent or an organic solvent may be used.
Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of 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 Amides such as dimethylacetamide; aprotic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

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 effects of the present invention are not significantly impaired. 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 active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass. % Or less, preferably 3% by mass or less, more preferably 2% by mass or less. Within the above range, the applicability is not lowered, and the ratio of the active material in the positive electrode active material layer is not lowered, so that it is difficult to reduce the battery capacity and increase the resistance between the positive electrode active materials.

The positive electrode active material layer obtained by applying and drying the slurry is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer is preferably 1 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 nonaqueous electrolyte permeates near the current collector / active material interface, and the charge / discharge characteristics at a high current density are unlikely to deteriorate. Since the conductivity between the active materials is unlikely to decrease, the battery resistance is hardly increased.

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 metal thin film of the current collector is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. . If the metal thin film is thinner than the above range, the strength required for the current collector may be insufficient. Moreover, when a thin film is thicker than the said range, a handleability may be impaired.

  The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but the (active material layer thickness on one side immediately before the nonaqueous electrolyte injection) / (thickness of the current collector) is usually 150 or less. It is preferably 20 or less, particularly preferably 10 or less, usually 0.1 or 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 is less likely to generate heat due to Joule heat during high current density charge / discharge, and the battery capacity is also unlikely to decrease.

[2-4. (Separator)
Usually, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit.
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 the glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyethersulfone, glass filters and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. When the thickness of the separator is within the above range, the insulating properties and mechanical strength are difficult to decrease. In addition, battery performance such as rate characteristics is not easily 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 usually 20% or more, preferably 35% or more, more preferably 45% or more, Moreover, it is 90% or less normally, 85% or less is preferable and 75% or less is still more preferable. When the porosity is within the above range, the membrane resistance is hardly increased and the rate characteristic is improved. Moreover, it is excellent in the mechanical strength of the separator, and the insulation is difficult to be lowered.

Moreover, although the average pore diameter of a separator is also arbitrary, it is 0.5 micrometer or less normally, 0.2 micrometer or less is preferable, and it is 0.05 micrometer or more normally. When the average pore diameter is within the above range, short-circuiting hardly occurs, the film resistance is not increased, and the rate characteristic is excellent.
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 thereof, a thin film shape such as a nonwoven fabric, a woven fabric, a microporous film or the like 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 the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

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 1-4, Comparative Examples 1-2]
<Preparation of non-aqueous electrolyte>
Nonaqueous electrolytes were prepared with the compositions shown in Table 1, respectively. The preparation example of Example 1 is described below. This applies to the cases other than Example 1.

Under a dry argon atmosphere, 1 mol · dm ^{−3 of} fully dried LiPF ₆ was added to a mixture of fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC) (volume ratio 2: 8).
Then, the compound (2-L) was added so as to be 1% by mass with respect to the non-aqueous electrolyte solution to prepare an electrolyte solution.

The compounds listed in Table 1 are as follows.
EMC indicates ethyl methyl carbonate.

Other additives A, B and C represent the following compounds.

<Preparation of positive electrode>
94% by mass of lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, 3% by mass of acetylene black as a conductive material, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder, an N-methylpyrrolidone solvent Mixed in to a slurry. The resulting slurry was applied to both sides of an aluminum foil having a thickness of 12 μm so as to be 50 mg per square centimeter, dried, and rolled to a thickness of 85 μm with a press machine. The active material had a width of 30 mm and a length of A positive electrode was cut out to be 40 mm. The prepared positive electrode was used after being dried under reduced pressure at 80 degrees Celsius for 12 hours.

<Production of negative electrode>
As the negative electrode active material, 73.2 parts by mass of silicon, which is a non-carbon material, 8.1 parts by mass of copper, and 12.2 parts by mass of artificial graphite powder (trade name “KS-6” manufactured by Timcal) were used. To this, 54.2 parts by mass of an N-methylpyrrolidone solution containing 12 parts by mass of polyvinylidene fluoride and 50 parts by mass of N-methylpyrrolidone were added and mixed with a disperser to form a slurry. The obtained slurry was uniformly applied onto a negative electrode current collector 18 μm thick copper foil to form a negative electrode, and then pressed so that the electrode density was about 1.5 g · cm ^−3. A negative electrode (silicon alloy negative electrode) was cut out to have a width of 30 mm and a length of 40 mm. The negative electrode was dried under reduced pressure at 60 degrees Celsius for 12 hours.

<Creation 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. This battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and then 0.4 mL of non-aqueous electrolyte was put into the bag. This was injected and vacuum sealed to produce a sheet battery. Furthermore, in order to improve the adhesion between the electrodes, the sheet-like battery was sandwiched between glass plates and pressurized.

<Battery evaluation>
1. Cycle test
The sheet-like battery was stabilized by charging and discharging several cycles at a constant current corresponding to 0.2 C at 25 ° C. with a charge end voltage of 4.2 V and a discharge end voltage of 3 V. Thereafter, charge and discharge were repeated 100 times at 45 ° C. with a current corresponding to 0.5 C. The ratio of the discharge capacity at the 100th time to the discharge capacity at the first time in the cycle test was evaluated as a discharge capacity maintenance rate (%).

Compared to Comparative Example 1 using the electrolytic solution not containing the compound of the present invention, in Examples 1 to 3 using the electrolytic solution containing the compound of the present invention, the discharge capacity retention rate was improved. Moreover, compared with the comparative example 2 using the electrolyte solution which does not contain the compound of this invention, in Examples 4 thru | or 6 using the electrolyte solution containing the compound of this invention, the discharge capacity maintenance factor improved. Therefore, it can be said to be effective even when added or when the solvent was changed, and other additives. In Comparative Example 3, the compound (C) having one divalent group represented by the general formula (1) in the molecule and diethyl oxalate have a discharge capacity retention rate as compared with Comparative Example 2 containing no additive. Declined. From these facts, it can be said that the compound of the present invention having two or more divalent groups represented by the general formula (1) in the molecule has an effect of suppressing a decrease in capacity when charge and discharge are repeated.

2. High temperature storage test The battery was stabilized in the same manner as in the above cycle test. Then, after performing 4.3V-constant current constant voltage charge (0.05C cut), the high temperature storage test was done on condition of 60 degreeC and 7 days. Before and after this high-temperature storage, the sheet-like battery was immersed in an ethanol bath, and the amount of gas generated from the volume change (high-temperature storage gas amount) was determined. The gas amount at this time is shown as a value when Comparative Example 1 is 1.

Compared to Comparative Example 1 using a non-aqueous electrolyte containing no compound of the present invention, in Examples 1 to 3 using an electrolyte containing the amide compound of the present invention, the amount of high-temperature storage gas decreased.
From these facts, it can be said that the compound of the present invention has an effect of suppressing gas generation during high-temperature storage in a charged state.
Example 7: Synthesis of compound 2-L
While stirring 8.4 g of 1,6-hexanediol, 17.9 g of triethylamine, and solvent THF (tetrahydrofuran) in a 300 mL reaction vessel, 24 g of ethyl chloroglyoxylate was cooled to −40 ° C. or lower. Slowly added. The reaction vessel was removed from the refrigerant, brought to room temperature, and stirred for 4 hours. The solid produced in the reaction solution was removed by filtration, and the liquid obtained after extraction and drying was distilled to synthesize Compound 2-L.

As a result of the GC mass spectrum analysis, 319 pseudo-molecular ion peaks were detected. This is considered a proton adduct of compound 2-L.
Moreover, the result of the analysis by NMR is shown below.

From the above results, it can be seen that the product is compound 2-L.
Example 8: Synthesis of compound 2-M
While stirring 10.6 g of 1,12-dodecanediol, 12.2 g of triethylamine, and solvent chloroform in a 200 mL reaction vessel while cooling 17.4 g of ethyl chloroglyoxylate to below -40 ° C, slowly And added. Remove the reaction vessel from the refrigerant to room temperature,
Stir all day and night. The solid produced in the reaction solution was removed by filtration, and the solid obtained after extraction and drying was purified by recrystallization to synthesize Compound 2-M.

Further, as a result of analysis of the GC mass spectrum, 403 pseudo-molecular ion peaks were detected. This is considered a proton adduct of compound 2-M.
Moreover, the result of the analysis by NMR is shown below.

From the above results, it can be seen that the product is compound 2-M.
Example 9: Synthesis of compound 2-Q
While stirring 15 g of 1,12-diaminododecane, 19.3 g of triethylamine, and chloroform as a solvent in a 300 mL reaction vessel, 25.6 g of ethyl chloroglyoxylate was added to -40.
The solution was slowly added while being cooled to below. The reaction vessel was removed from the refrigerant, brought to room temperature, and stirred for a whole day and night. The solid produced in the reaction solution was removed by filtration, and the solid obtained after extraction and drying was purified by recrystallization to synthesize Compound 2-Q.
Further, as a result of analysis of the GC mass spectrum, 401 pseudo-molecular ion peaks were detected. This is considered a proton adduct of compound 2-Q.
Moreover, the result of the analysis by NMR is shown below.

  From the above results, it can be seen that the product is compound 2-Q.

According to the non-aqueous electrolyte of the present invention, the decomposition of the electrolyte of the non-aqueous electrolyte secondary battery is suppressed, and when the battery is used in a high temperature environment, gas generation and deterioration of the battery are suppressed and a high capacity is achieved. A non-aqueous electrolyte secondary battery with high energy density and excellent cycle characteristics can be manufactured. Therefore, it can be suitably used in various fields such as an electronic device in which the nonaqueous electrolyte secondary battery is used.
The use of the non-aqueous electrolyte for secondary batteries 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 include notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, game machines, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini Power supplies for portable electronic devices such as discs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, electric tools, etc., large power supplies for mobile objects such as hybrid cars, electric cars, electric bikes, electric bicycles, or Examples thereof include a home power supply device for the purpose of leveling the electric power load, a stationary large-scale power supply such as a backup power supply, and the like.

Claims (3)

In non-aqueous electrolyte for a battery containing an electrolyte and a nonaqueous solvent, a battery for a non-aqueous electrolyte solution, characterized by containing a compound (A) represented by the following general formula (2).

(Wherein R ¹ and R ³ each represent an —OR ⁴ group. R ⁴ represents a hydrocarbon group having 1 to 5 carbon atoms which may have a halogen atom. In the formula, R ² represents —OR. ⁸ O— represents a divalent group selected from the group consisting of —NR ¹⁰ —R ¹¹ —NR ¹² — group, and R ⁸ and R ¹¹ each have 1 to 20 carbon atoms which may have a halogen atom.
The following divalent hydrocarbon groups are represented, and R ¹⁰ and R ¹² represent a hydrocarbon group having 1 to 5 carbon atoms which may have a halogen atom or a hydrogen atom. ) 2. The battery non-aqueous electrolyte according to claim 1, wherein the compound (A) is contained in a ratio of 0.001% by mass to 10% by mass with respect to the whole battery non-aqueous electrolyte. Negative, it a non-aqueous electrolyte battery comprising the non-aqueous electrolyte for the positive electrode and the battery, the nonaqueous electrolyte battery is a battery for a non-aqueous electrolyte solution according to any one of claims 1 to 2 Non-aqueous electrolyte battery characterized by the above.