WO2020170833A1

WO2020170833A1 - Electrolyte composition, nonaqueous electrolyte, and nonaqueous electrolyte secondary battery

Info

Publication number: WO2020170833A1
Application number: PCT/JP2020/004511
Authority: WO
Inventors: 広幸長田; 宏美竹之内; 英晃長野; 貴久寒河江; 健二撹上; 洋平青山
Original assignee: 株式会社Adeka
Priority date: 2019-02-19
Filing date: 2020-02-06
Publication date: 2020-08-27
Also published as: KR20210126569A; JPWO2020170833A1; CN113228373A

Abstract

This electrolyte composition contains at least one compound selected from the group consisting of compounds represented by general formula (1), and at least one item selected from a solvent and a dispersion medium. (In the formula, R¹ is a hydrocarbon group with 1-8 carbon atoms, R²-R⁵ are independently a hydrogen atom, a hydrocarbon group with 1-8 carbon atoms, etc., R⁶ is a hydrocarbon group with 1-8 carbon atoms, etc., and n is an integer between 1 and 4.)

Description

Electrolyte composition, non-aqueous electrolyte and non-aqueous electrolyte secondary battery

The present invention relates to a composition for electrolyte, a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery.

Non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are used in portable electronic devices such as portable personal computers, handy video cameras, and information terminals. Widely used as a power source. From the viewpoint of environmental problems, electric vehicles that use non-aqueous electrolyte secondary batteries and hybrid vehicles that use electric power as a part of power have been put into practical use. Therefore, in recent years, further improvement in performance of secondary batteries has been demanded.

A non-aqueous electrolyte secondary battery is composed of members such as a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The positive electrode and the negative electrode usually include a current collector and an electrode mixture layer formed on the current collector. The electrode mixture layer is formed, for example, by applying an electrode active material capable of occluding/releasing lithium ions and a slurry composition obtained by dispersing a binder and the like in a dispersion medium onto a current collector and drying.

As a method of improving the performance of the secondary battery, a method of using an additive in the non-aqueous electrolyte has been proposed. For example, vinylene carbonate (for example, see Patent Document 1), methylphenyl carbonate (for example, see Patent Document 2), (tetrafluorobenzo-1,2-dioxyl)-pentafluorophenyl-borane (for example, Patent Document 3). ), methyl pyruvate (see, for example, Patent Document 4), dimethyl malonate (see, for example, Patent Document 5), N,N-dimethylsulfonamide (see, for example, Patent Document 6), vinylsulfonamide. (For example, refer to Patent Document 7), pentafluorophenylmethyl oxalate (for example, refer to Patent Document 8), phenylsilane (for example, refer to Patent Document 9), etc. are added to the non-aqueous electrolyte to improve cycle characteristics. It is said that battery performance such as charge and discharge capacity and storage characteristics at high temperature can be improved.

Japanese Patent Laid-Open No. 2000-123867 Japanese Patent Laid-Open No. 08-293323 Japanese Patent Publication No. 2008-532248 International Publication No. 2006/070546 JP-A-2002-376673 JP, 2004-259697, A JP, 2013-93242, A JP 2007-121373A JP, 2008-210769, A

However, although many electrolyte additives have been developed to improve battery performance, the cycle characteristics (maintaining capacity of battery capacity after repeated charging/discharging) are not sufficient, and further improvement of cycle characteristics is not enough. There is also a need for excellent rate characteristics, in which the capacity is less likely to decrease even if the battery is charged and discharged in a short time, and it is necessary to improve the cycle characteristics and the rate characteristics at the same time.

Therefore, an object of the present invention is to provide a composition for an electrolyte that can improve the cycle characteristics and rate characteristics of a non-aqueous electrolyte secondary battery.

That is, the present invention is for an electrolyte containing at least one compound selected from the group consisting of compounds represented by the following general formulas (1) to (4) and at least one compound selected from a solvent and a dispersion medium. It is a composition.

(In the formula, R ¹ is a hydrocarbon group having 1 to 8 carbon atoms, and R ² to R ⁵ are each independently a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, or a carbon atom having 1 carbon atom. An alkoxy group having 1 to 6 or the following formula (1-a), wherein R ⁶ is a nitro group, a sulfonic acid group, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or the following formula In the formula (1-b) or the following formula (1-c), when R ⁶ is a hydrocarbon group having 1 to 8 carbon atoms, n is an integer of 1 to 4 and R ⁶ is nitro. Group, sulfonic acid group, alkoxy group having 1 to 6 carbon atoms or the following formula (1-b), n=1, and R ⁶ is the following formula (1-c): , N=2.)

(* in the formula represents the bonding position.)

(In the formula, R ⁷ is the following formula (1-d) or the following formula (1-e).)

(In the formula, R ⁸ to R ¹⁶ are each independently a hydrogen atom, an unsubstituted hydrocarbon group having 1 to 8 carbon atoms, or 1 to 8 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms. Hydrocarbon group, an unsubstituted alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms in which a part of hydrogen atoms have been replaced by a fluorine atom, an unsubstituted alkoxy group having 1 to 6 carbon atoms Thioalkoxy group, thioalkoxy group having 1 to 6 carbon atoms in which some hydrogen atoms are substituted with fluorine atoms, sulfonyl group having a hydrocarbon group having 1 to 8 carbon atoms, or carbonization having 1 to 8 carbon atoms It is an acyl group having a hydrogen group, and * represents the bonding position.)

(In the formula, when m=1 or 2, and m=1, R ¹⁷ to R ¹⁹ are each independently a hydrocarbon group having 1 to 8 carbon atoms, and R ¹⁸ and R ¹⁹ are linked to each other. To form a ring, and when m=2, R ¹⁷ and R ¹⁹ are each independently a hydrocarbon group having 1 to 8 carbon atoms, and R ¹⁸ is a single bond.)

(In the formula, R ²⁰ and R ²¹ are each independently a hydrocarbon group having 1 to 8 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and R ²² to R ³¹ are independently hydrogen. An atom, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogen atom or a nitro group.)

According to the present invention, it is possible to provide a composition for an electrolyte capable of improving the cycle characteristics and rate characteristics of a non-aqueous electrolyte secondary battery.

1 is a vertical cross-sectional view schematically showing an example of the structure of a coin-type battery of a non-aqueous electrolyte secondary battery of the present invention. It is a schematic diagram showing the basic composition of the cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention. 1 is a perspective view showing the internal structure of a cylindrical battery of a non-aqueous electrolyte secondary battery of the present invention as a cross section.

<Composition for electrolyte>
The composition for electrolyte of the present invention contains at least one compound selected from the group consisting of compounds represented by the following general formulas (1) to (4) and at least one compound selected from a solvent and a dispersion medium. To do.

(* in the formula represents the bonding position.)

Examples of the hydrocarbon group having 1 to 8 carbon atoms which represents R ¹ to R ⁵ in the compound represented by the general formula (1) include an aliphatic hydrocarbon group and an aromatic hydrocarbon group.
Specifically, methyl group, ethyl group, propyl group, i-propyl group, butyl group, 2-butyl group, i-butyl group, t-butyl group, pentyl group, 2-pentyl group, 3-pentyl group, Saturated aliphatic compounds such as i-pentyl group, hexyl group, 2-hexyl group, 3-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group, methylcyclohexyl group and norbornane group Unsaturated aliphatic hydrocarbon groups such as hydrocarbon group, vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, cyclopentenyl group, cyclohexenyl group, cyclooctenyl group, norbornene group, phenyl group, methylphenyl group, ethyl Examples thereof include aromatic hydrocarbon groups such as phenyl group, phenylmethyl group, phenylethyl group, benzyl group. The saturated aliphatic hydrocarbon group and the unsaturated aliphatic hydrocarbon group may have a linear structure, a branched structure or a cyclic structure.

Examples of the alkoxy group having 1 to 6 carbon atoms which represents R ² to R ⁵ include a methoxy group, an ethoxy group, a propoxy group, an i-propoxy group, a butoxy group, a pentoxy group, a hexyloxy group and a cyclohexyloxy group. To be

Examples of the hydrocarbon group having 1 to 8 carbon atoms representing R ⁶ include the same ones as the hydrocarbon group having 1 to 8 carbon atoms in R ¹ to R ⁵ .

Examples of the alkoxy group having 1 to 6 carbon atoms which represents R ⁶ include the same ones as the alkoxy group having 1 to 6 carbon atoms in R ² to R ⁵ .

As a specific example of the compound represented by the general formula (1), R ¹ is a hydrocarbon group having 1 to 8 carbon atoms, and R ² to R ⁵ are each independently a hydrogen atom or 1 carbon atom. To a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or the above formula (1-a), wherein R ⁶ is a nitro group, a sulfonic acid group, a hydrocarbon group having 1 to 8 carbon atoms or carbon When it is an alkoxy group having 1 to 6 atoms and n=1, examples thereof include compounds represented by the following 1-1 to 1-61, but the invention is not limited thereto.

As a specific example of the compound represented by the general formula (1), R ¹ is a hydrocarbon group having 1 to 8 carbon atoms, and R ² to R ⁵ are hydrogen atoms or carbon atoms having 1 to 8 carbon atoms. When it is a hydrogen group, R ⁶ is the above formula (1-b) or the above formula (1-c), and n=1 or 2, for example, compounds represented by the following 1-62 to 1-70 are However, the present invention is not limited to these.

As a specific example of the compound represented by the general formula (1), R ¹ is a hydrocarbon group having 1 to 8 carbon atoms, and R ² to R ⁵ are hydrogen atoms or carbon atoms having 1 to 8 carbon atoms. When it is a hydrogen group, R ⁶ is a hydrocarbon group having 1 to 8 carbon atoms, and n is an integer of 2 to 4, examples thereof include compounds represented by the following 1-71 to 1-78. , But is not limited to these.

R ¹ of the compound represented by the general formula (1) is preferably an aliphatic hydrocarbon group having 1 to 6 carbon atoms, a phenyl group or a benzyl group because of excellent cycle characteristics and rate characteristics, It is more preferably a methyl group, an allyl group, a t-butyl group or a benzyl group, and R ² to R ⁵ are each a hydrogen atom, a saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, or the above formula (1- a) is preferable, and R ⁶ is a nitro group, a sulfonic acid group, a saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, the above formula (1-b) or the above formula (1-c). Preferably. Above all, 1-1, 1-2, 1-16, 1-17, 1-37, 1-39, 1-40, 1-41, 1-50, 1-51, 1-52, 1-54 , 1-56, 1-62, 1-64, 1-67, 1-70, 1-72, 1-75, 1-77 and 1-78 are more preferable, and the above-mentioned 1-1, The compounds represented by 1-37, 1-39, 1-40, 1-52, 1-62, 1-70, 1-72, 1-75, 1-77 and 1-78 are more preferable.

As a method for producing the compound represented by the general formula (1), for example, a carbonate compound such as methyl 4-methylphenyl carbonate is used in the presence of an organic base as compared with a phenol compound such as 4-methylphenol. It can be efficiently obtained by reacting a chloroformate such as a mate.

Of the compound represented by the general formula (2), the above formula represents an R ⁷ (1-d) and represents the R ⁸ ~ R ¹⁶ in the formula (1-e), the unsubstituted carbon atoms of 1 to 8 Specific examples of the hydrocarbon group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a 2-butyl group, an i-butyl group, a t-butyl group, a pentyl group and a 2-pentyl group. , 3-pentyl group, i-pentyl group, hexyl group, 2-hexyl group, 3-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, cyclopentyl group, cyclohexyl group, methylcyclohexyl group, norbornane Unsaturated hydrocarbon groups such as saturated aliphatic hydrocarbon groups such as groups, vinyl groups, allyl groups, butenyl groups, pentenyl groups, hexenyl groups, cyclopentenyl groups, cyclohexenyl groups, aromatic hydrocarbons such as phenyl groups Groups. R ⁸ to R ¹⁶ may be those in which a part of hydrogen atoms in these hydrocarbon groups are substituted with fluorine atoms. The saturated aliphatic hydrocarbon group and the unsaturated aliphatic hydrocarbon group may have a linear structure, a branched structure or a cyclic structure.

Of the compound represented by the general formula (2), the above formula represents an R ⁷ (1-d) and represents the R ⁸ ~ R ¹⁶ in the formula (1-e), of the unsubstituted carbon atoms of 1 to 6 Examples of the alkoxy group include the same ones as the alkoxy group having 1 to 6 carbon atoms which represents R ² to R ⁵ in the compound represented by the general formula (1). R ⁸ to R ¹⁶ may be an alkoxy group in which a part of hydrogen atoms are replaced with fluorine atoms.

Of the compound represented by the general formula (2), the above formula represents an R ⁷ (1-d) and represents the R ⁸ ~ R ¹⁶ in the formula (1-e), of the unsubstituted carbon atoms of 1 to 6 Examples of the thioalkoxy group include groups in which the alkoxy group having 1 to 6 carbon atoms, which represents R ¹ to R ⁵ , of the compound represented by the general formula (1) is bonded by a sulfur atom instead of an oxygen atom. R ⁸ to R ¹⁶ may be a thioalkoxy group in which some hydrogen atoms are replaced with fluorine atoms.

Examples of the hydrocarbon group having 1 to 8 carbon atoms contained in the sulfonyl group or the acyl group include hydrocarbon groups having 1 to 8 carbon atoms represented by R ¹ to R ⁵ of the compound represented by the general formula (1). The same can be mentioned.

Specific examples of the compound represented by the general formula (2) include, but are not limited to, the compounds represented by the following 2-1 to 2-24.

Since R ⁸ , R ⁹ , R ¹¹ and R ^{12 in the} above formula (1-d) representing R ⁷ of the compound represented by the general formula (2) are hydrogen atoms, since they are excellent in cycle characteristics and rate characteristics, It is preferable that R ¹⁰ is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a thioalkoxy group having 1 to 4 carbon atoms, or a fluoromethoxy group. A fluorothiomethoxy group, a sulfonyl group having an aliphatic hydrocarbon group having 1 to 4 carbon atoms or an acyl group having an aliphatic hydrocarbon group having 1 to 4 carbon atoms is preferable, and a methoxy group or a thiomethoxy group is preferable. A trifluoromethoxy group or a methylsulfonyl group is more preferable. R ¹⁴ to R ¹⁶ in the above formula (1-e) representing R ⁷ of the compound represented by the general formula (2) are preferably hydrogen atoms because they have excellent cycle characteristics and rate characteristics. Among them, the compounds represented by the above 2-1, 2-2, 2-6, 2-7, 2-10, 2-11, 2-12, 2-14, 2-18 and 2-22 are more preferable. The compounds represented by the above 2-1, 2-10, 2-11, 2-12, 2-14 and 2-22 are more preferable.

As a method for producing the compound represented by the general formula (2), for example, an oxalate ester compound such as diphenyl oxalate is prepared by reacting an oxalyl chloride with an alcohol compound such as phenol in the presence of an organic base. It can be obtained efficiently.

Examples of the hydrocarbon group having 1 to 8 carbon atoms which represents R ¹⁷ to R ¹⁹ in the compound represented by the general formula (3) include R ¹ to R ⁵ in the compound represented by the general formula (1). The same as the represented hydrocarbon group having 1 to 8 carbon atoms can be mentioned.

Specific examples of the compound represented by the general formula (3) include, but are not limited to, the compounds represented by the following 3-1 to 3-14.

The compound represented by the general formula (3) is preferably an aliphatic hydrocarbon having 1 to 3 carbon atoms as R ^{17 in} the case of m=1, since it has excellent cycle characteristics and rate characteristics. It is more preferably a methyl group or an ethyl group, and R ¹⁸ and R ¹⁹ are each an aliphatic hydrocarbon group having 1 to 3 carbon atoms or a cyclohexyl group in which R ¹⁸ and R ¹⁹ form a ring. When m=2, R ¹⁷ and R ¹⁹ are preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms. Among them, the compounds represented by 3-1, 3-6, 3-9, 3-10 and 3-12 are more preferable, and the compounds represented by 3-1, 3-9 and 3-12 are further preferable. preferable.

As a method for producing the compound represented by the general formula (3), for example, a sulfonic acid oxime compound such as propanone methanesulfonic acid oxime is used in the presence of an organic base, a sulfonyl chloride such as methanesulfonyl chloride, and an acetoxime It can be efficiently obtained by reacting the oxime compound of

Examples of the hydrocarbon group having 1 to 8 carbon atoms which represents R ²⁰ to R ³¹ of the compound represented by the general formula (4) include R ¹ to R ⁵ of the compound represented by the general formula (1). The same as the represented hydrocarbon group having 1 to 8 carbon atoms can be mentioned. The alkoxy group having 1 to 6 carbon atoms which represents R ²⁰ to R ³¹ is the same as the alkoxy group having 1 to 6 carbon atoms which represents R ² to R ⁵ in the compound represented by the general formula (1). Is mentioned.

Specific examples of the compound represented by the general formula (4) include, but are not limited to, the compounds represented by the following 4-1 to 4-24.

R ²⁰ and R ²¹ of the compound represented by the general formula (4) are preferably an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and a methyl group because they have excellent cycle characteristics and rate characteristics. More preferably, R ²² , R ²³ , R ²⁵ to R ²⁸ , R ³⁰ and R ³¹ are each preferably a hydrogen atom or a fluorine atom, more preferably a hydrogen atom, and R ²⁴ and R ^{As 29} , a hydrogen atom, a fluorine atom, an aliphatic hydrocarbon group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms or a nitro group is preferable, and a fluorine atom or a nitro group is preferable. More preferable. Of these, the compounds represented by 4-1, 4-3, 4-9, 4-13, 4-16 and 4-19 are more preferable, and the compounds represented by 4-3, 4-13 and 4-16 are more preferable. Are more preferred.

As a method for producing the compound represented by the general formula (4), for example, a silane compound such as bis(4-fluorophenoxy)dimethylsilane is used in the presence of an organic base with respect to a chlorosilane compound such as dimethyldichlorosilane. -It can be efficiently obtained by reacting a phenol compound such as fluorophenol.

The form of the composition for an electrolyte of the present invention is not particularly limited, a liquid form obtained by using an organic solvent as a solvent, a solvent or a dispersion medium, a high molecular compound dissolved in an organic solvent to form a gel. Examples thereof include a polymer gel form obtained by using a molecular gel and a polymer form obtained by using a polymer as a dispersion medium without using a solvent.

As the solvent used in the composition for an electrolyte of the present invention, an organic solvent usually used for a non-aqueous electrolyte of a non-aqueous electrolyte secondary battery can be used. Specific examples of the organic solvent include, for example, saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds, amide compounds, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, saturated chain ester compounds, etc. Is mentioned. These organic solvents may be used alone or in combination of two or more. Among these organic solvents, a saturated cyclic carbonate compound, a saturated cyclic ester compound, a sulfoxide compound, a sulfone compound and an amide compound are preferable because they have a high relative dielectric constant and play a role of increasing the dielectric constant of the electrolyte composition. A saturated cyclic carbonate compound is more preferable.

Examples of the saturated cyclic carbonate compound include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate and 1,1-dimethylethylene carbonate. To be
Examples of the saturated cyclic ester compound include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-hexanolactone, δ-octanolactone and the like.
Examples of the sulfoxide compound include dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, diphenyl sulfoxide, thiophene and the like.
Examples of the sulfone compound include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, diphenyl sulfone, sulfolane (also referred to as tetramethylene sulfone), 3-methylsulfolane, 3,4-dimethylsulfolane, 3,4-diphenymethylsulfolane, Examples thereof include sulfolene, 3-methylsulfolene, 3-ethylsulfolene, 3-bromomethylsulfolene and the like. Among these, sulfolane and tetramethylsulfolane are preferable.
Examples of the amide compound include N-methylpyrrolidone, dimethylformamide, dimethylacetamide and the like.

Among organic solvents, saturated chain carbonates can be used in that the viscosity of the composition for electrolyte can be lowered, and the mobility of electrolyte ions can be increased to improve the battery characteristics such as output density. Compounds, chain ether compounds, cyclic ether compounds and saturated chain ester compounds are preferred. A saturated chain carbonate compound is particularly preferable because it has a low viscosity and can enhance the performance of the composition for electrolytes at low temperatures.

Examples of the saturated chain carbonate compound include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl butyl carbonate, methyl-t-butyl carbonate, diisopropyl carbonate, t-butyl propyl carbonate and the like.
Examples of the chain ether compound and the cyclic ether compound include dimethoxyethane, ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, dioxane, 1,2-bis(methoxycarbonyloxy)ethane, 1,2-bis(ethoxycarbonyl). Oxy)ethane, 1,2-bis(ethoxycarbonyloxy)propane, ethylene glycol bis(trifluoroethyl)ether, propylene glycol bis(trifluoroethyl)ether, ethylene glycol bis(trifluoromethyl)ether, diethylene glycol bis(tri Examples thereof include fluoroethyl) ether, and among these, dioxolane is preferable.

The saturated chain ester compound is preferably a monoester compound or a diester compound having a total number of carbon atoms in the molecule of 2 to 8, and specific compounds include, for example, methyl formate, ethyl formate, methyl acetate, acetic acid. Ethyl, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, trimethyl ethyl acetate, methyl malonate, ethyl malonate, methyl succinate, ethyl succinate, Examples thereof include methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetyl, propylene glycol diacetyl, etc., methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate. , And ethyl propionate are preferred.

As other organic solvents, for example, acetonitrile, propionitrile, nitromethane, their derivatives, and various ionic liquids can be used.

Examples of the polymer used for preparing the polymer gel type composition include polyethylene oxide, polypropylene oxide, polyvinyl chloride, polyacrylonitrile, polymethylmethacrylate, polyethylene, polyvinylidene fluoride, and polyhexafluoropropylene.
Examples of the polymer used for preparing the polymer form composition include polyethylene oxide, polypropylene oxide, polystyrene sulfonic acid and the like.
There is no particular limitation on the compounding ratio in the polymer gel or polymer composition, and the compounding method, and the compounding ratio and the compounding method known in the art can be used.

The content of at least one compound selected from the group consisting of the compounds represented by the general formulas (1) to (4) is 0.01% by mass to 10% by mass based on the composition for an electrolyte of the present invention. Is preferred, 0.05% by mass to 10% by mass is more preferred, and 0.1% by mass to 5% by mass is even more preferred. When the content of the compounds represented by the general formulas (1) to (4) is less than 0.01% by mass, the cycle characteristics and rate characteristics of the non-aqueous electrolyte secondary battery using the composition for electrolyte of the present invention In some cases, the effect of improving is not sufficient. On the other hand, if the content of the compounds represented by the general formulas (1) to (4) is more than 10% by mass, the effect corresponding to the blending amount cannot be obtained, which may adversely affect the battery characteristics.

The form of the composition for an electrolyte of the present invention is not particularly limited, but it is preferable that the composition contains a solvent, and it is more preferable that it be in a liquid form because the manufacturing process is simple.

<Non-aqueous electrolyte>
The non-aqueous electrolyte of the present invention contains the above-mentioned composition for electrolytes and a supporting electrolyte. Examples of the supporting electrolyte include alkali metal salts such as lithium salt, sodium salt and potassium salt, magnesium salt, calcium salt and the like.

The lithium salt used in the non-aqueous electrolyte of the present invention is not particularly limited, and known lithium salts can be used. Specific examples of the lithium salt include, for example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN. (SO ₂ F) ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiB(CF ₃ SO ₃ ) ₄ , LiB(C ₂ O ₄ ) ₂ , LiBF ₂ (C ₂ O ₄ ), LiSbF ₆ , LiSiF ₅ , LiSCN _{, LiClO 4, LiCl, LiF,} LiBr, LiI, LiAlF 4, LiAlCl 4, LiPO 2 F 2 , and derivatives thereof.
The liquid and polymer gel electrolyte compositions include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN. One or more lithium salts selected from the group consisting of (SO ₂ F) ₂ , LiPO ₂ F ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiCF ₃ SO ₃ derivatives and LiC(CF ₃ SO ₂ ) ₃ derivatives. Is preferably used.
Polymeric electrolyte compositions include LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiB( It is preferable to use one or more selected from the group consisting of CF ₃ SO ₃ ) ₄ and LiB(C ₂ O ₄ ) ₂ .

The sodium salt and potassium salt used in the non-aqueous electrolyte of the present invention are not particularly limited, and known sodium salt and potassium salt can be used.

The magnesium salt and calcium salt used in the non-aqueous electrolyte of the present invention are not particularly limited, and known magnesium salt and calcium salt can be used.

If the concentration of the supporting electrolyte in the non-aqueous electrolyte is too low, a sufficient current density may not be obtained, while if it is too high, the stability of the non-aqueous electrolyte may be impaired. It is preferably ˜7 mol/L, more preferably 0.8 mol/L to 1.8 mol/L.

The use of the non-aqueous electrolyte of the present invention is not particularly limited, but it can be suitably used as a non-aqueous electrolyte used in a non-aqueous electrolyte secondary battery.

The non-aqueous electrolyte of the present invention may further contain known electrolyte additives such as an electrode film forming agent, an antioxidant, a flame retardant, and an overcharge preventing agent for improving battery life and safety. When the concentration of the electrolyte additive is too low, the effect of addition cannot be exhibited, and when the concentration is too high, the characteristics of the non-aqueous electrolyte secondary battery may be adversely affected. The content is preferably 0.01% by mass to 10% by mass, and more preferably 0.1% by mass to 5% by mass.

<Non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and the above-mentioned non-aqueous electrolyte. In the present invention, it is preferable to interpose a separator between the positive electrode and the negative electrode. Hereinafter, the non-aqueous electrolyte secondary battery of the present invention will be described.

The positive electrode used in the present invention can be manufactured according to a known method. For example, a mixture containing a positive electrode active material, a binder, and a conductive auxiliary agent is applied to a current collector by applying an electrode mixture paste prepared by slurrying it with an organic solvent or water, and then dried to form an electrode mixture on the current collector. A layered positive electrode can be manufactured.

A known positive electrode active material can be used. Examples of known positive electrode active materials include lithium transition metal composite oxides, lithium-containing transition metal phosphate compounds, lithium-containing silicate compounds, lithium-containing transition metal sulfate compounds, and the like. As the transition metal of the lithium-transition metal composite oxide, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper and the like are preferable. These positive electrode active materials may be used alone or in combination of two or more.

Specific examples of the lithium transition metal composite oxide 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 _3. A part of the transition metal atom that is the main constituent of these lithium-transition metal composite oxides, such as aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, and zirconium. Those substituted with other metals may be mentioned. The lithium transition metal composite oxide in which a part of the main transition metal atom is replaced with another metal is, for example, Li _1.1 Mn _1.8 Mg _0.1 O ₄ , Li _1.1 Mn _1.85 Al _0.05 O ₄ , LiNi _0.5 Co _0.2 Mn _0.3. O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.80 Co _0.17 Al _0.03 O ₂ , LiNi _0.80 Co _0.15 Al _0.05 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiNi _0.5 Mn _1.5 O ₄ , Li ₂ MnO ₃ -LiMO ₂ (M=Co, Ni, Mn) and the like.

As the transition metal of the lithium-containing transition metal phosphate compound, vanadium, titanium, manganese, iron, cobalt, nickel and the like are preferable, and specific examples thereof include LiFePO ₄ , LiM _x Fe _1-x PO ₄ (M=Co , Ni, Mn) etc., iron phosphate compounds such as LiCoPO ₄ , cobalt phosphate compounds such as LiCoPO ₄ , and some of the transition metal atoms that are the main constituents of these lithium transition metal phosphate compounds are aluminum, titanium, vanadium, chromium, Substituted with other metals such as manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, and niobium, vanadium phosphate compounds such as Li ₃ V ₂ (PO ₄ ) _{3 and the} like. To be

Examples of the lithium-containing silicate compound include Li ₂ FeSiO ₄ .

Examples of the lithium-containing transition metal sulfuric acid compound include LiFeSO ₄ , LiFeSO ₄ F and the like.

As the positive electrode active material, sulfur, a sulfur-modified organic compound, a sulfur-carbon composite, or Li ₂ S _x (x=1 to 8) can also be used.

As sulfur, any of various forms such as powdered sulfur, insoluble sulfur, precipitated sulfur and colloidal sulfur can be used. Powdered sulfur is preferable because it is uniformly dispersed in the electrode mixture paste.

The sulfur-modified organic compound is a mixture of sulfur and a polyacrylonitrile compound, an elastomer compound, a pitch compound, a polynuclear aromatic ring compound, an aliphatic hydrocarbon oxide, a polyether compound, a polythienoacene compound, a polyamide compound, a hexachlorobutadiene compound, It can be produced by heat denaturation at 250° C. to 600° C. in a non-oxidizing gas atmosphere. The non-oxidizing gas atmosphere has an oxygen concentration of less than 5% by volume, preferably less than 2% by volume, and more preferably an atmosphere containing substantially no oxygen, that is, an atmosphere of nitrogen, helium, argon or the like. It is an active gas atmosphere or a sulfur gas atmosphere. From the viewpoint of obtaining a larger charge/discharge capacity, the sulfur content in the sulfur-modified organic compound is preferably 25% by mass to 80% by mass. Among these sulfur-modified organic compounds, the sulfur-modified polyacrylonitrile compound is preferable because it can provide a large charge/discharge capacity and stable cycle characteristics.

The sulfur-carbon composite is a composite of sulfur and carbon mechanically, a composite of sulfur and carbon chemically, or a simple substance of sulfur contained in the pores of porous carbon. And can be used as an electrode active material of a secondary battery capable of inserting and extracting lithium ions. If the sulfur content in the sulfur-carbon composite is too low, the charge/discharge capacity does not increase, and if it is too high, the electron conductivity decreases, so 25% by mass to 90% by mass is preferable, and 30% by mass to 70% by mass. Mass% is more preferable. As a method of supporting elemental sulfur in the pores of the porous carbon, a known method can be adopted.

The sulfur content in the sulfur-modified organic compound and the sulfur-carbon complex can be calculated by elemental analysis using a CHN analyzer capable of analyzing sulfur and oxygen, for example, a Vario MICRO cube manufactured by Elementer.

If the particle size of the positive electrode active material is too large, it may not be possible to obtain a uniform and smooth electrode mixture layer, while if it is too small, the handling property in the slurrying step will decrease, so the average particle size of the positive electrode active material will be reduced. The diameter (D50) is preferably 0.5 μm to 100 μm, more preferably 1 μm to 50 μm, and further preferably 1 μm to 30 μm.

In the present invention, the average particle diameter (D50) means a 50% particle diameter measured by a laser diffraction light scattering method. The particle diameter is a volume-based diameter, and the diameter of secondary particles is measured by the laser diffraction light scattering method.

The positive electrode active material can be made into a desired particle size by a method such as pulverization or granulation. The pulverization may be dry pulverization performed in a gas or wet pulverization performed in a liquid such as water. Examples of industrial pulverization methods include a ball mill, roller mill, turbo mill, jet mill, cyclone mill, hammer mill, pin mill, rotary mill, vibration mill, planetary mill, attritor, and bead mill.

Known binders can be used. Specific examples of the binder include, for example, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene-diene rubber, styrene-isoprene rubber, fluororubber, polyethylene, polypropylene, polyacrylamide, polyamide, polyamideimide, polyimide, Polyacrylonitrile, polyurethane, polyvinylidene fluoride, polytetrafluoroethylene, styrene-acrylic acid ester copolymer, ethylene-vinyl alcohol copolymer, polymethyl methacrylate, polyacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, polyvinyl ether, Examples thereof include polyvinyl chloride, acrylic acid, polyacrylic acid, methyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose nanofibers and starch. The binder may be used alone or in combination of two or more.

The content of the binder is preferably 0.5 parts by mass to 30 parts by mass, and more preferably 1 part by mass to 20 parts by mass with respect to 100 parts by mass of the positive electrode active material.

As the conduction aid, those known as a conduction aid for electrodes can be used. Specific examples of the conductive additive include, for example, natural graphite, artificial graphite, coal tar pitch, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, roller black, disk black, carbon. Carbon materials such as nanotubes, vapor grown carbon fibers (VGCF), exfoliated graphite, graphene, fullerene, needle coke; metal powders such as aluminum powder, nickel powder, titanium powder; zinc oxide, titanium oxide, etc. Conductive metal oxides; sulfides such as La ₂ S ₃ , Sm ₂ S ₃ , Ce ₂ S ₃ and TiS ₂ .

The average particle diameter (D50) of the conductive additive is preferably 0.0001 μm to 100 μm, more preferably 0.01 μm to 50 μm.

The content of the conductive additive is usually 0.1 parts by mass to 50 parts by mass, preferably 0.5 parts by mass to 30 parts by mass, and preferably 1 part by mass to 100 parts by mass of the electrode active material. It is more preferably 20 parts by mass.

As a solvent for preparing the electrode mixture paste for the positive electrode, for example, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, acetonitrile, propylene carbonate, etc. Pionitrile, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, 1,3-dioxolane, nitromethane, N-methylpyrrolidone, N,N-dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyl triamine, N , N-dimethylaminopropylamine, polyethylene oxide, tetrahydrofuran, dimethylsulfoxide, sulfolane, γ-butyrolactone, water, alcohol and the like. The amount of the solvent used can be adjusted according to the coating method selected when coating the electrode mixture paste. For example, in the case of coating by the doctor blade method, the total of the positive electrode active material, the binder and the conductive additive. The amount is preferably 15 parts by mass to 300 parts by mass, and more preferably 30 parts by mass to 200 parts by mass, relative to 100 parts by mass.

The electrode mixture paste for the positive electrode contains, in addition to the above components, other components such as a viscosity modifier, a reinforcing material, an antioxidant, a pH modifier, and a dispersant, in a range that does not impair the effects of the present invention. You may let me. As these other components, known components can be used in a known mixing ratio.

In the production of the electrode mixture paste, when the positive electrode active material, the binder and the conductive auxiliary agent are dispersed or dissolved in the solvent, all of them may be collectively added to the solvent for dispersion treatment, or they may be added separately for dispersion treatment. May be. It is preferable to sequentially add the binder, the conductive auxiliary agent, and the positive electrode active material in this order to the solvent for dispersion treatment, because these can be uniformly dispersed in the solvent. When the electrode mixture paste contains other components, the other components can be collectively added for dispersion treatment, but it is preferable to perform the dispersion treatment every time one other component is added.

The method of dispersion treatment is not particularly limited, but as an industrial method, for example, a usual ball mill, sand mill, bead mill, cyclone mill, pigment disperser, grinder, ultrasonic disperser, homogenizer, rotation/revolution mixer, A planetary mixer, a fill mix, a jet pasta, etc. can be used.

As the current collector, a conductive material such as titanium, titanium alloy, aluminum, aluminum alloy, nickel, stainless steel, nickel plated steel, or carbon is used. Examples of the shape of the current collector include a foil shape, a plate shape, a net shape, a foam shape, and a non-woven cloth shape. The current collector may be porous or non-porous. In addition, these conductive materials may be surface-treated in order to improve adhesion and electrical characteristics. Among these conductive materials, aluminum is preferable and aluminum foil is particularly preferable from the viewpoint of conductivity and price. The thickness of the current collector is not particularly limited, but is usually 5 μm to 30 μm.

The method of applying the electrode mixture paste of the positive electrode onto the current collector is not particularly limited, and examples thereof include die coater method, comma coater method, curtain coater method, spray coater method, gravure coater method, flexo coater method, knife coater. Method, doctor blade method, reverse roll method, brush coating method, dip method and the like can be used. The die coater method, the knife coater method, the doctor blade method and the comma coater method are preferable in that a good coating layer surface state can be obtained in accordance with the viscosity and the drying property of the electrode mixture paste.

The application of the electrode mixture paste for the positive electrode onto the current collector may be performed on one side or both sides of the current collector. When it is applied to both sides of the current collector, it may be applied one side at a time or may be applied to both sides simultaneously. Further, it may be applied continuously, intermittently or in stripes on the surface of the current collector. The thickness, length and width of the coating layer can be appropriately determined according to the size of the battery and the like.

The method for drying the electrode mixture paste for the positive electrode applied on the current collector is not particularly limited, and a known method can be used. Examples of the drying method include drying with warm air, hot air, and low humidity air, vacuum drying, and drying by irradiating with far infrared rays, infrared rays, electron beams, or the like, which is left standing in a heating furnace or the like. These drying methods may be carried out in combination. The temperature for heating is generally about 50° C. to 180° C., but conditions such as temperature can be appropriately set depending on the application amount of the electrode mixture paste, the boiling point of the solvent used, and the like. By this drying, the volatile components such as the solvent volatilize from the coating film of the electrode mixture paste, and the electrode mixture layer is formed on the current collector.

When a material containing no lithium such as a sulfur-modified organic compound and a sulfur-carbon composite is used as the positive electrode active material, lithium can be pre-doped. The method of doping the material may be a known method. For example, a half battery is assembled using metallic lithium as the counter electrode, and lithium is inserted by an electrolytic doping method in which lithium is electrochemically doped. Alternatively, a metallic lithium foil is attached to an electrode and then left in an electrolytic solution. Then, a method of inserting lithium by a pasting dope method of doping by utilizing diffusion of lithium to an electrode, a mechanical doping method of mechanically colliding a positive electrode active material and a lithium metal, and inserting lithium. However, it is not limited to these.

The negative electrode used in the present invention can be manufactured according to a known method. For example, a mixture containing a negative electrode active material, a binder, and a conductive auxiliary agent is applied to a current collector by applying an electrode mixture paste prepared by slurrying it with an organic solvent or water, and then dried to form an electrode mixture on the current collector. A layered negative electrode can be manufactured.

A known negative electrode active material can be used. Known negative electrode active materials include, for example, natural graphite, artificial graphite, non-graphitizable carbon, graphitizable carbon, lithium, lithium alloy, silicon, silicon alloy, silicon oxide, tin, tin alloy, tin oxide, phosphorus, germanium. , Indium, copper oxide, antimony sulfide, titanium oxide, iron oxide, manganese oxide, cobalt oxide, nickel oxide, lead oxide, ruthenium oxide, tungsten oxide, zinc oxide, LiVO ₂ , Li ₂ VO ₄ , Li ₄ Ti ₅ O ₁₂ , complex oxides such as titanium-niobium-based oxides and the like can be mentioned. These negative electrode active materials may be used alone or in combination of two or more.

As the negative electrode active material, sulfur, a sulfur-modified organic compound, a sulfur-carbon composite, or Li ₂ S _x (x=1 to 8) can also be used. As the sulfur, sulfur-modified organic compound, and sulfur-carbon composite that can be used as the negative electrode active material, use the same sulfur, sulfur-modified organic compound, and sulfur-carbon composite that can be used as the positive electrode active material. You can

If the particle size of the negative electrode active material is too large, it may not be possible to obtain a uniform and smooth electrode mixture layer, while if it is too small, the handling property in the slurrying process will decrease, so the average particle size of the negative electrode active material. The diameter (D50) is preferably 0.01 μm to 100 μm, more preferably 0.5 μm to 50 μm, and further preferably 1 μm to 30 μm.

The negative electrode active material can be made into a desired particle size by a method such as pulverization or granulation. The pulverization may be dry pulverization performed in a gas or wet pulverization performed in a liquid such as water. Examples of the industrial pulverization method include a ball mill, a roller mill, a turbo mill, a jet mill, a cyclone mill, a hammer mill, a pin mill, a rotary mill, a vibration mill, a planetary mill, an attritor, and a bead mill.

Known binders can be used. Specific examples of the binder include those similar to the binder used for the positive electrode. The binder may be used alone or in combination of two or more.

The content of the binder is preferably 1 part by mass to 30 parts by mass, and more preferably 1 part by mass to 20 parts by mass with respect to 100 parts by mass of the negative electrode active material.

As the conductive additive, a known conductive additive for electrodes can be used. Specific examples of the conductive additive include those similar to the conductive additive used for the positive electrode.

The content of the conductive additive is usually 0 parts by mass to 50 parts by mass, preferably 0 parts by mass to 30 parts by mass, and 0.5 parts by mass to 20 parts by mass with respect to 100 parts by mass of the electrode active material. More preferably, it is a part.

As the solvent for preparing the electrode mixture paste for the negative electrode, the same solvents as those used for preparing the electrode mixture paste for the positive electrode can be mentioned. The amount of the solvent used can be adjusted according to the coating method selected when coating the electrode mixture paste, for example, in the case of coating by the doctor blade method, the total amount of the negative electrode active material, the binder and the conductive additive. The amount is preferably 15 parts by mass to 300 parts by mass, more preferably 30 parts by mass to 200 parts by mass, relative to 100 parts by mass.

The electrode mixture paste of the negative electrode contains, in addition to the above components, other components such as a viscosity adjusting agent, a reinforcing material, an antioxidant, a pH adjusting agent, and a dispersant as long as the effects of the present invention are not impaired. You may let me. As these other components, known components can be used in a known mixing ratio.

The negative electrode mixture paste can be manufactured by mixing, dispersing and manufacturing in the same process as the positive electrode mixture paste manufacturing process except that the negative electrode active material is used instead of the positive electrode active material.

As the current collector, a conductive material such as titanium, titanium alloy, aluminum, aluminum alloy, copper, nickel, stainless steel, nickel plated steel, or carbon is used. Examples of the shape of the current collector include a foil shape, a plate shape, a net shape, a foam shape, and a non-woven cloth shape. The current collector may be porous or non-porous. In addition, these conductive materials may be surface-treated in order to improve adhesion and electrical characteristics. Among these conductive materials, copper is preferable, and copper foil is particularly preferable, from the viewpoint of stability at negative electrode potential, conductivity, and price. The thickness of the current collector is not particularly limited, but is usually 3 μm to 30 μm.

When the negative electrode active material is a metal or a metal alloy such as lithium, a lithium alloy, tin, or a tin alloy, the electrode mixture paste is not prepared using a binder, a conductive auxiliary agent, or a solvent, and the metal or alloy is, for example, a plate-like material. It can also be used in the form of a sheet, a film, or the like. When the alloy is used as the negative electrode active material, the negative electrode active material itself has a high electron conductivity, so that it is not necessary to use a current collector. However, depending on the structure of the battery, an alloy is formed with the negative electrode active material. A metal material that does not exist can also be used as the negative electrode current collector.

The method of applying the electrode mixture paste of the negative electrode onto the current collector is not particularly limited, and examples thereof include a coating method used when manufacturing the positive electrode.

The application of the electrode mixture paste for the negative electrode onto the current collector may be performed on one side or both sides of the current collector. When it is applied to both sides of the current collector, it may be applied one side at a time or may be applied to both sides simultaneously. Further, it may be applied continuously, intermittently or in stripes on the surface of the current collector. The thickness, length and width of the coating layer can be appropriately determined according to the size of the battery and the like.

The method of drying the electrode mixture paste of the negative electrode applied on the current collector is not particularly limited, and a known method can be used. Examples of the drying method include drying with warm air, hot air, and low humidity air, vacuum drying, and drying by irradiating with far infrared rays, infrared rays, electron beams, or the like, which is left standing in a heating furnace or the like. These drying methods may be carried out in combination. The temperature for heating is generally about 50° C. to 180° C., but conditions such as temperature can be appropriately set depending on the application amount of the electrode mixture paste, the boiling point of the solvent used, and the like. By this drying, the volatile components such as the solvent volatilize from the coating film of the electrode mixture paste, and the electrode mixture layer is formed on the current collector.

When using a material such as a silicon-based material, a tin-based material, or a sulfur-based material that has a large initial irreversible reaction as the negative electrode active material, lithium can be pre-doped. The method of doping the material may be a known method. For example, assembling a half-cell using metallic lithium as the counter electrode and inserting lithium by an electrolytic doping method in which lithium is electrochemically doped, or by attaching a metallic lithium foil to an electrode and then leaving it in an electrolytic solution Then, a method of inserting lithium by a pasting dope method of doping by utilizing diffusion of lithium to the electrode, a mechanical dope method of mechanically colliding a negative electrode active material and lithium metal, and inserting lithium. However, it is not limited to these.

As the separator, a commonly used polymer film, glass film or the like can be used without particular limitation. Specific examples of the polymer film include, for example, polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyether sulfone, polycarbonate, polyamide, polyimide, polyethylene oxide and polypropylene. Polyethers such as oxides, various celluloses such as carboxymethyl cellulose and hydroxypropyl cellulose, polymer compounds mainly containing poly(meth)acrylic acid and various esters thereof, derivatives thereof, copolymers thereof, and the like. Examples include films made of a mixture, and these films may be coated with a ceramic material such as alumina or silica, magnesium oxide, an aramid resin, or polyvinylidene fluoride. These films can be used alone or can be used as a multilayer film by superposing these polymer films. Further, various additives can be used in these polymer films, and the kind and content thereof are not particularly limited. Among these polymer films, a film made of polyethylene, polypropylene, polyvinylidene fluoride or polysulfone is preferably used.

 These polymer films are microporous so that the non-aqueous electrolyte can penetrate and the ions can easily permeate. As the method of making micropores, a “phase separation method” in which a solution of a polymer compound and a solvent is subjected to microphase separation to form a film, and the solvent is extracted and removed to make the polymer porous, and a molten polymer compound is highly drafted. The film is extruded into a film and then heat-treated to arrange the crystals in one direction, and further, a "stretching method" in which a gap is formed between the crystals to form a porosity, which is appropriately selected depending on the polymer film used. It

The shape of the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and various shapes such as coin type battery, cylindrical type battery, rectangular type battery and laminated type battery can be used. FIG. 1 is a vertical cross-sectional view schematically showing an example of the structure of a coin-type battery of the non-aqueous electrolyte secondary battery of the present invention. FIG. 2 is a schematic diagram showing the basic configuration of a cylindrical battery of the non-aqueous electrolyte secondary battery of the present invention. FIG. 3 is a perspective view showing the internal structure of a cylindrical battery of the non-aqueous electrolyte secondary battery of the present invention as a cross section.

A coin-type non-aqueous electrolyte secondary battery 10 shown in FIG. 1 includes a positive electrode current collector 1a, a positive electrode mixture layer 1 formed on the positive electrode current collector 1a and capable of releasing lithium ions, a positive electrode current collector 1a and a positive electrode current collector 1a. A positive electrode case 4 containing a positive electrode composed of the positive electrode mixture layer 1, a negative electrode current collector 2a, and a lithium ion formed on the negative electrode current collector 2a, which absorbs and releases lithium ions released from the positive electrode mixture layer 1 A negative electrode mixture layer 2 that can be formed, a negative electrode case 5 that accommodates a negative electrode composed of the negative electrode current collector 2 a and the negative electrode mixture layer 2, and a separator 7. The interiors of the positive electrode case 4 and the negative electrode case 5 are filled with the non-aqueous electrolyte 3. Further, the peripheral portions of the positive electrode case 4 and the negative electrode case 5 are sealed by being caulked with a polypropylene gasket 6.

The cylindrical non-aqueous electrolyte secondary battery 10 ′ shown in FIGS. 2 and 3 includes an electrode body in which a negative electrode plate 19 and a positive electrode plate 21 are wound with a separator 7 in between, and a case 23 for housing the electrode body. , A pair of insulating plates 24 arranged so as to sandwich the electrode body. The positive electrode plate 21 is composed of a positive electrode current collector 1a and a positive electrode mixture layer 1 formed on the positive electrode current collector 1a and capable of releasing lithium ions. The negative electrode plate 19 includes a negative electrode current collector 2a and a negative electrode mixture layer 2 formed on the negative electrode current collector 2a and capable of absorbing and releasing lithium ions released from the positive electrode mixture layer 1. The inside of the case 23 is filled with the non-aqueous electrolyte 3. At the open end of the case 23, the positive electrode terminal 17 and a safety valve 26 and a PTC (Positive Temperature Coefficient) element 27 provided inside the positive electrode terminal 17 are sealed by being caulked via a gasket 6. The negative electrode plate 19 is connected to the negative electrode terminal 18 via a negative electrode lead 20. The positive electrode plate 21 is connected to the positive electrode terminal 17 via a positive electrode lead 22.

As the exterior member used for the positive electrode case 4, the negative electrode case 5, and the case 23, a metal container, a laminated film, etc. may be mentioned. The thickness of the exterior member is usually 0.5 mm or less, preferably 0.3 mm or less. Examples of the shape of the exterior member include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type.

The metal container can be formed of, for example, stainless steel, aluminum, an aluminum alloy, or the like. As the aluminum alloy, an alloy containing an element such as magnesium, zinc or silicon is preferable. By setting the content of transition metals such as iron, copper, nickel, and chromium in aluminum or an aluminum alloy to 1% by mass or less, long-term reliability and heat dissipation in a high temperature environment can be dramatically improved. ..

As the laminate film, a multilayer film having a metal layer between resin films can be used. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. For the resin film, for example, a polymer material such as polypropylene, polyethylene, nylon, polyethylene terephthalate can be used. The laminate film can be sealed by heat fusion to form an exterior member.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Without departing from the scope of the present invention, various modifications and improvements can be made by those skilled in the art.

The present invention will be described in more detail below by showing Examples and Comparative Examples. The present invention is not limited to these examples.

<Production of Positive Electrode A>
94.0 parts by mass of NCM622 (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , manufactured by Beijing Tosho Co., Ltd.) as a positive electrode active material, 3.0 parts by mass of acetylene black (Denka Black, manufactured by Denka Co., Ltd.) as a conduction aid, and a binder. As a solvent, 3.0 parts by mass of polyvinylidene fluoride (manufactured by Kureha Co., Ltd.) and 90 parts by mass of N-methylpyrrolidone as a solvent were dispersed using a planetary mixer to obtain a slurry electrode mixture paste. This electrode mixture paste was applied to one side of a current collector made of aluminum foil (thickness: 15 μm) by the doctor blade method, dried at 90° C., and then press-molded. After that, the electrode was cut into a predetermined size and further vacuum dried at 130° C. for 3 hours immediately before use to prepare a positive electrode A.

<Production of Negative Electrode A>
96.6 parts by mass of artificial graphite (MAGD: manufactured by Hitachi Chemical Co., Ltd.) as a negative electrode active material, 0.4 parts by mass of acetylene black (Denka Black, manufactured by Denka Co., Ltd.) as a conductive additive, and styrene-butadiene rubber (40 2.0% by mass of a mass% aqueous dispersion, manufactured by Nippon Zeon Co., Ltd., 1.0 part by mass of sodium carboxymethylcellulose (CMCNa: manufactured by Daicel FineChem), and 120 parts by mass of water as a solvent, using a planetary mixer. And dispersed to obtain a slurry-like electrode mixture paste. This electrode mixture paste was applied to one side of a current collector made of copper foil (thickness 10 μm) by the doctor blade method, dried at 90° C., and then press-molded. After that, the electrode was cut into a predetermined size and further vacuum dried at 130° C. for 3 hours immediately before use to prepare a negative electrode A.

<Battery preparation-1>
[Example 1]
A solution was prepared by dissolving LiPF ₆ as a supporting electrolyte at a concentration of 1.0 mol/L in a mixed solvent consisting of 50% by volume of ethylene carbonate and 50% by volume of diethyl carbonate. To this, 1.0% by mass of compound 1-1 was added to obtain a non-aqueous electrolyte.
A positive electrode A cut into a disk shape and a negative electrode A cut into a disk shape were used, and a polypropylene film (manufactured by Celgard) was sandwiched between the separators and held in a case. Then, the previously prepared non-aqueous electrolyte was injected into the case and sealed with a caulking machine to prepare a non-aqueous electrolyte secondary battery of Example 1 (coin type having a diameter of 20 mm and a thickness of 3.2 mm). The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of Charge/Discharge Evaluation-1, and the results are shown in Table 1.

[Example 2]
A non-aqueous electrolyte secondary battery of Example 2 was produced in the same manner as in Example 1 except that 0.1% by mass of Compound 1-1 was added to the non-aqueous electrolyte. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of Charge/Discharge Evaluation-1, and the results are shown in Table 1.

[Example 3]
A non-aqueous electrolyte secondary battery of Example 3 was produced in the same manner as in Example 1 except that Compound 1-1 was added to the non-aqueous electrolyte in an amount of 5.0% by mass. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of Charge/Discharge Evaluation-1, and the results are shown in Table 1.

[Examples 4 to 25]
Nonaqueous electrolyte secondary batteries of Examples 4 to 25 were produced in the same manner as in Example 1 except that the compounds shown in Table 1 were added to the nonaqueous electrolyte instead of the compound 1-1. The numbers in parentheses added to the compound numbers in Table 1 show the weight fraction (mass %) of each additive compound in the non-aqueous electrolyte. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of Charge/Discharge Evaluation-1, and the results are shown in Table 1.

[Comparative Examples 1 to 7]
Non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 7 were prepared in the same manner as in Example 1 except that the following compounds 5-1 to 5-7 were added to the non-aqueous electrolyte instead of the compound 1-1. .. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of Charge/Discharge Evaluation-1, and the results are shown in Table 1.

[Comparative Example 8]
A non-aqueous electrolyte secondary battery of Comparative Example 8 was produced by the same operation as in Example 1 except that Compound 1-1 was not added. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of Charge/Discharge Evaluation-1, and the results are shown in Table 1.

<Charge/discharge evaluation-1>
The nonaqueous electrolyte secondary batteries of Examples 1 to 25 and Comparative Examples 1 to 8 were placed in a constant temperature bath at 25° C., the charge end voltage was 4.20 V, the discharge end voltage was 2.75 V, and the charge rate was 0.2 C. A charge/discharge test at a discharge rate of 0.2C was performed 5 times, and a charge/discharge test at a charge rate of 2C and a discharge rate 2C was performed 5 times. Then, the battery was placed in a constant temperature bath at 45° C., and a charge/discharge test was performed 100 times at a charge rate of 0.5 C and a discharge rate of 0.5 C, for a total of 110 times, and the discharge capacity (mAh/g) per positive electrode active material was measured. .. Ratio of discharge capacity at 5th time and discharge capacity at 10th time (L1), and ratio of discharge capacity at 110th time and discharge capacity at 11th time (L2, L2=discharge capacity at 110th time/discharge capacity at 11th time) Is shown in Table 1.

<Production of sulfur-modified polyacrylonitrile>
After adding 200 parts by mass of sulfur (manufactured by Sigma-Aldrich, particle size 200 μm, powder) and 100 parts by mass of polyacrylonitrile powder (manufactured by Sigma-Aldrich, classified by a sieve having an opening diameter of 30 μm) to an alumina Tammann tube The opening of the alumina Tammann tube was covered with a rubber plug to which a thermocouple, a gas inlet tube and a gas outlet tube were attached. While introducing argon gas into the alumina Tamman tube at a flow rate of 100 cc/min, the mixture was heated at a temperature rising rate of 5° C./min, and when the temperature reached 100° C., the argon gas was stopped. Thereafter, the heating was stopped at 360°C, but the temperature rose to 400°C. After cooling to around room temperature, the reaction product was taken out from the alumina Tammann tube. The obtained reaction product was pulverized to obtain sulfur-modified polyacrylonitrile (sometimes referred to as SPAN). The average particle size and sulfur content of SPAN were as follows.
・Average particle size 10μm
・Sulfur content 38.4% by mass

<Production of Positive Electrode B>
90.0 parts by mass of SPAN as a positive electrode active material, 5.0 parts by mass of acetylene black (Denka Black, manufactured by Denka) as a conductive additive, and styrene-butadiene rubber (40% by mass aqueous dispersion, manufactured by Nippon Zeon) as a binder. ), 2.0 parts by mass of sodium carboxymethyl cellulose (CMCNa, manufactured by Daicel FineChem) and 120 parts by mass of water as a solvent, and the slurry-like electrode mixture is dispersed by using a rotation/revolution mixer. An agent paste was obtained. This electrode mixture paste was applied by a doctor blade method to one side of a current collector made of carbon-coated aluminum foil (thickness: 22 μm), dried at 90° C., and then press-molded. After that, the electrode was cut into a predetermined size and further vacuum dried at 130° C. for 3 hours immediately before use. After that, a half battery using the nonaqueous electrolyte of Comparative Example 8 was assembled using metallic lithium as a counter electrode, and lithium was electrochemically doped to produce a positive electrode B.

<Battery preparation-2>
[Example 26]
A solution was prepared by dissolving LiPF ₆ at a concentration of 1.0 mol/L in a mixed solvent consisting of 50% by volume of ethylene carbonate and 50% by volume of diethyl carbonate. Compound 1-37 was added to this in an amount of 1.0% by mass to give a non-aqueous electrolyte.
A positive electrode B cut into a disk shape and a negative electrode A cut into a disk shape were used, and a polypropylene film (manufactured by Celgard) was sandwiched between the separators and held in a case. Then, the non-aqueous electrolyte prepared above was injected into the case and sealed with a caulking machine to prepare a non-aqueous electrolyte secondary battery of Example 26 (coin type having a diameter of 20 mm and a thickness of 3.2 mm). The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of charge/discharge evaluation-2, and the results are shown in Table 2.

[Examples 27 to 29]
Non-aqueous electrolyte secondary batteries of Examples 27 to 29 were produced in the same manner as in Example 26, except that the compounds shown in Table 2 were added instead of the compound 1-37. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of charge/discharge evaluation-2, and the results are shown in Table 2.

[Comparative Example 9]
A non-aqueous electrolyte secondary battery of Comparative Example 9 was produced by the same operation as in Example 26 except that Compound 1-37 was not added. The cycle characteristics and rate characteristics of the produced non-aqueous electrolyte secondary battery were evaluated by the method of charge/discharge evaluation-2, and the results are shown in Table 2.

<Charge/discharge evaluation-2>
The non-aqueous electrolyte secondary batteries of Examples 26 to 29 and Comparative Example 9 were placed in a constant temperature bath at 25° C., the charge end voltage was 3.0 V, the discharge end voltage was 0.7 V, and the charge rate was 0.2 C and the discharge rate. The 0.2 C charge/discharge test was performed 5 times, and the charge rate 2 C and discharge rate 2 C charge/discharge tests were performed 5 times. Then, the battery was placed in a constant temperature bath at 45° C., and a charge/discharge test was performed 100 times at a charge rate of 0.5 C and a discharge rate of 0.5 C, for a total of 110 times, and the discharge capacity (mAh/g) per positive electrode active material was measured. .. Ratio of discharge capacity at 5th time and discharge capacity at 10th time (L3), and ratio of discharge capacity at 110th time and discharge capacity at 11th time (L4, L4=discharge capacity at 110th time/discharge capacity at 11th time) Is shown in Table 2.

From the results of Tables 1 and 2, by using the composition for electrolyte of the present invention, a non-aqueous electrolyte secondary battery with improved cycle characteristics and rate characteristics can be produced.

1 Positive electrode mixture layer 1a Positive electrode current collector 2 Negative electrode mixture layer 2a Negative electrode current collector 3 Non-aqueous electrolyte 4 Positive electrode case 5 Negative electrode case 6 Gasket 7 Separator 10 Coin type non-aqueous electrolyte secondary battery 10' Cylindrical non- Water electrolyte secondary battery 17 Positive electrode terminal 18 Negative electrode terminal 19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode plate 22 Positive electrode lead 23 Case 24 Insulating plate 26 Safety valve 27 PTC element

Claims

At least one compound selected from the group consisting of compounds represented by the following general formulas (1) to (4),
A composition for an electrolyte containing at least one selected from a solvent and a dispersion medium.

(In the formula, R 1 is a hydrocarbon group having 1 to 8 carbon atoms, and R 2 to R 5 are each independently a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, or a carbon atom having 1 carbon atom. An alkoxy group having 1 to 6 or the following formula (1-a), wherein R 6 is a nitro group, a sulfonic acid group, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or the following formula In the formula (1-b) or the following formula (1-c), when R 6 is a hydrocarbon group having 1 to 8 carbon atoms, n is an integer of 1 to 4 and R 6 is nitro. Group, sulfonic acid group, alkoxy group having 1 to 6 carbon atoms or the following formula (1-b), n=1, and R 6 is the following formula (1-c): , N=2.)

(* in the formula represents the bonding position.)

(In the formula, R 7 is the following formula (1-d) or the following formula (1-e).)

(In the formula, R 8 to R 16 are each independently a hydrogen atom, an unsubstituted hydrocarbon group having 1 to 8 carbon atoms, or 1 to 8 carbon atoms in which a part of hydrogen atoms are substituted with fluorine atoms. Hydrocarbon group, an unsubstituted alkoxy group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms in which a part of hydrogen atoms have been replaced by a fluorine atom, an unsubstituted alkoxy group having 1 to 6 carbon atoms Thioalkoxy group, thioalkoxy group having 1 to 6 carbon atoms in which some hydrogen atoms are substituted with fluorine atoms, sulfonyl group having a hydrocarbon group having 1 to 8 carbon atoms, or carbonization having 1 to 8 carbon atoms It is an acyl group having a hydrogen group, and * represents the bonding position.)

(In the formula, when m=1 or 2, and m=1, R 17 to R 19 are each independently a hydrocarbon group having 1 to 8 carbon atoms, and R 18 and R 19 are linked to each other. To form a ring, and when m=2, R 17 and R 19 are each independently a hydrocarbon group having 1 to 8 carbon atoms, and R 18 is a single bond.)

(In the formula, R 20 and R 21 are each independently a hydrocarbon group having 1 to 8 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and R 22 to R 31 are independently hydrogen. An atom, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogen atom or a nitro group.)
The composition for an electrolyte according to claim 1, wherein R 1 in the general formula (1) contains a compound which is a methyl group, an allyl group, a t-butyl group or a benzyl group.
R 7 in the general formula (2) is the formula (1-d), R 8 , R 9 , R 11 and R 12 in the formula (1-d) are hydrogen atoms, and R 10 is a methoxy group. The composition for electrolytes according to claim 1, containing a compound which is a thiomethoxy group, a trifluoromethoxy group or a methylsulfonyl group.
The electrolyte according to claim 1, wherein R 7 in the general formula (2) is the formula (1-e), and R 14 to R 16 in the formula (1-e) is a hydrogen atom. Composition.
The composition for electrolytes according to claim 1, containing a compound in which R 17 in the general formula (3) is a methyl group or an ethyl group.
In the general formula (4), R 20 and R 21 are methyl groups, R 24 and R 29 are fluorine atoms or nitro groups, and R 22 , R 23 , R 25 , R 26 , R 27 , R 28 , The composition for electrolytes according to claim 1, containing a compound in which R 30 and R 31 are hydrogen atoms.
A composition for an electrolyte according to any one of claims 1 to 6,
A non-aqueous electrolyte, including a supporting electrolyte.
The positive electrode,
Negative electrode,
A non-aqueous electrolyte secondary battery comprising the non-aqueous electrolyte according to claim 7.