JP2019220415A - Composition, nonaqueous electrolyte and nonaqueous electrolyte secondary battery - Google Patents

Abstract

To provide a nonaqueous electrolyte secondary battery arranged so as to be able to suppress the decrease in electric capacity owing to the iteration of charge and discharge, and having storage stability while retaining high safety.SOLUTION: A composition comprises: a compound represented by the general formula (1) below; a compound represented by the general formula (2) below; a lithium salt; and a solvent and/or dispersion medium. (In the formulas, Rand Rindependently represent a hydrogen atom, a carbon hydride group with 1-6 carbon atoms or the like, Rto Rindependently represent a hydrogen atom, a halogen atom, a carbon hydride group with 1-6 carbon atoms or the like, and Rto Rindependently represent a halogen atom, a carbon hydride group with 1-6 carbon atoms or an alkoxy group with 1-6 carbon atoms.)SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composition containing a specific component, a non-aqueous electrolyte, and a non-aqueous electrolyte secondary battery using the same.

  Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries having a non-aqueous electrolyte in which a lithium salt is dispersed or dissolved in a dispersion medium such as an organic solvent are small, lightweight, have a high energy density, and are repeatedly charged. Since it can be discharged, it is widely used as a power source for portable electronic devices such as portable personal computers, handy video cameras, and information terminals. Further, from the viewpoint of environmental problems, electric vehicles using non-aqueous electrolyte secondary batteries and hybrid vehicles using electric power as a part of power have been put to practical use. Therefore, in recent years, further improvements in the performance of secondary batteries have been demanded from the viewpoints of the usable time of portable electronic devices, the cruising distance of automobiles, and their safety.

  In order to improve the performance of a non-aqueous electrolyte secondary battery, various compounds to be added to a non-aqueous electrolyte (hereinafter, sometimes referred to as an electrolyte additive, an electrolyte additive, or simply an additive) have been proposed. As such electrolyte additives, 1,3-propane sultone (see, for example, Patent Document 1), vinylethylene carbonate (for example, see Patent Document 2), vinylene carbonate (for example, see Patent Document 3), 1 , 3-propane sultone, butane sultone (for example, see Patent Document 4), vinylene carbonate (for example, see Patent Document 5), vinylethylene carbonate (for example, see Patent Document 6), and the like, Vinylene carbonate is widely used because of its great effect. These electrolyte additives form a stable film called SEI (Solid Electrolyte Interface) on the surface of the negative electrode, and suppress the reductive decomposition of the electrolytic solution by covering the surface of the negative electrode with this film. It is believed that. As a result, it is possible to suppress a decrease in the capacity retention characteristics (hereinafter, sometimes referred to as cycle characteristics) due to repeated charging and discharging.

In addition, in non-aqueous electrolyte secondary batteries, when the batteries are used under abnormal conditions, and when an internal short circuit is caused or overcharged, the battery temperature rises rapidly due to decomposition of the battery members. When the safety valve is opened, an organic solvent or other decomposition gas may be ejected or smoke may be generated. Therefore, there is a need for a technique for improving battery safety without impairing battery performance.For example, in order to ensure internal short-circuiting of the battery and safety at high temperatures, a shutdown that melts at a high temperature and closes the holes is required. A technique of attaching a separator or a PTC element whose resistance increases with an increase in temperature is employed.
As a simpler technique, a technique has been disclosed in which a polymerizable aromatic compound such as biphenyl or thiophene is contained in a non-aqueous electrolyte as an electrolyte additive to enhance safety (for example, Patent Documents 7 and 8). , 9).

JP-A-63-102173 JP-A-4-87156 JP-A-5-74486 JP-A-10-50342 JP-A-8-045455 JP 2001-6729 A JP-A-09-106835 JP 2008-210768 A JP-A-2002-343423

  However, the suppression of a decrease in electric capacity due to repetition of charging and discharging disclosed in the above-mentioned prior patent document has not been sufficient yet. Further, a non-aqueous electrolyte secondary battery having high safety and storage stability is also required. An object of the present invention is to solve these problems.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by using a composition containing a compound having a specific structure as a non-aqueous electrolyte, and completed the present invention.

  The present invention provides a composition comprising a compound represented by the following general formula (1), a compound represented by the following general formula (2), a lithium salt, and a solvent and / or a dispersion medium. To provide.

(Wherein, R ¹ and R ² are each independently a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a heterocyclic group having 4 to 6 carbon atoms, and at least one hydrogen atom is a halogen atom. Represents a substituted hydrocarbon group having 1 to 6 carbon atoms or a heterocyclic group having 4 to 6 carbon atoms in which at least one hydrogen atom is substituted by a halogen atom.)

(Wherein, R ^{3 to} R ⁷ each independently represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a heterocyclic group having 4 to 6 carbon atoms, and at least one hydrogen atom Represents a hydrocarbon group having 1 to 6 carbon atoms substituted with a fluorine atom, or a heterocyclic group having 4 to 6 carbon atoms substituted with one or more hydrogen atoms with a fluorine atom,
R ^{8 to} R ¹⁰ each independently represent a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. )

  According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery in which a decrease in electric capacity due to repeated charge and discharge is suppressed, and which has high storage stability while maintaining high safety.

FIG. 1 is a longitudinal sectional view schematically showing an example of the structure of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 2 is a schematic diagram showing a basic configuration of a cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 3 is a perspective view showing the internal structure of the cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention as a cross section. FIG. 4 is an exploded perspective view schematically showing a laminated electrode group inside the laminated battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 5 is an exploded perspective view schematically showing a laminated battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 6 is an external plan view schematically showing a laminated battery of the nonaqueous electrolyte secondary battery of the present invention.

  Hereinafter, the composition, nonaqueous electrolyte, and nonaqueous electrolyte secondary battery of the present invention will be described in detail based on preferred embodiments.

<Composition>
The composition of the present invention contains a compound represented by the following general formula (1), a compound represented by the following general formula (2), a lithium salt, and a solvent and / or a dispersion medium.

(Wherein, R ¹ and R ² are each independently a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a heterocyclic group having 4 to 6 carbon atoms, and at least one hydrogen atom is a halogen atom. Represents a substituted hydrocarbon group having 1 to 6 carbon atoms or a heterocyclic group having 4 to 6 carbon atoms in which at least one hydrogen atom is substituted by a halogen atom.)

(Wherein, R ^{3 to} R ⁷ each independently represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a heterocyclic group having 4 to 6 carbon atoms, and at least one hydrogen atom Represents a hydrocarbon group having 1 to 6 carbon atoms substituted with a fluorine atom, or a heterocyclic group having 4 to 6 carbon atoms substituted with one or more hydrogen atoms with a fluorine atom,
R ^{8 to} R ¹⁰ each independently represent a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. )

Examples of the hydrocarbon group having 1 to 6 carbon atoms for R ¹ and R ² in the general formula (1) include a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic group. Group hydrocarbon groups and the like. Specifically, methyl, ethyl, propyl, i-propyl, butyl, 2-butyl, i-butyl, t-butyl, pentyl, 2-pentyl, 3-pentyl, saturated aliphatic hydrocarbon groups such as i-pentyl group, hexyl group, 2-hexyl group and 3-hexyl group; unsaturated aliphatic hydrocarbon groups such as vinyl group, allyl group, butenyl group, pentenyl group and hexenyl group; An alicyclic hydrocarbon group such as a cyclopentyl group and a cyclohexyl group; an aromatic hydrocarbon group such as a phenyl group;
Examples of the heterocyclic group having 4 to 6 carbon atoms in R ¹ and R ² in the general formula (1) include a thienyl group, a furanyl group, a pyridyl group, a thiolanyl group, an oxanyl group, a piperidyl group, and the like.
The hydrocarbon group having 1 to 6 carbon atoms and the heterocyclic group having 4 to 6 carbon atoms are such that at least one hydrogen atom is a halogen atom, specifically, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. May be substituted.

As R ¹ and R ² , a hydrogen atom, a methyl group, a vinyl group, or a phenyl group is preferable because excellent battery characteristics such as good cycle characteristics, high safety, and storage stability can be obtained. Groups or vinyl groups are more preferred.

When R ¹ is a hydrogen atom, specific examples of the compound represented by the general formula (1) include, for example, the following compounds No. 1-1 to No. 1-73, but are not limited thereto. Not something.

Further, as a specific example of the compound represented by the general formula (1), when R ¹ is a methyl group and R ² is a saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, for example, Compound No. 1-74 to No. 1-105 are exemplified, but not limited thereto.

Examples of the halogen atom in the general formula (2) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the hydrocarbon group having 1 to 6 carbon atoms and the heterocyclic group having 4 to 6 carbon atoms in R ^{3 to} R ⁷ in the general formula (2) include a carbon atom in R ¹ and R ² in the general formula (1). The same groups as the hydrocarbon groups having 1 to 6 and the heterocyclic groups having 4 to 6 carbon atoms can be used.
In the hydrocarbon group having 1 to 6 carbon atoms and the heterocyclic group having 4 to 6 carbon atoms, one or more hydrogen atoms may be substituted with a fluorine atom. Examples of the hydrocarbon group having 1 to 6 carbon atoms in which one or more hydrogen atoms are substituted with a fluorine atom include a saturated aliphatic group having 1 to 6 carbon atoms in which one or more hydrogen atoms are substituted with a fluorine atom. A hydrocarbon group, a cyclic saturated aliphatic hydrocarbon group having 5 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, or an aromatic hydrocarbon group in which at least one hydrogen atom is substituted with a fluorine atom And the like.
Examples of the aliphatic hydrocarbon group having 1 to 6 carbon atoms in which one or more hydrogen atoms are substituted with a fluorine atom include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 1-fluoroethyl group, Fluoroethyl group, 1-fluoroisopropyl group, 2-fluoroisopropyl group, 1-fluorobutyl group, 2-fluorobutyl group, 3-fluorobutyl group, 1-fluoroisobutyl group, 2-fluoroisobutyl group, 2-fluoro- Examples include a t-butyl group, a 1-fluoropentyl group, a 2-fluoropentyl group, a 3-fluoropentyl group, a 4-fluoropentyl group, a 1-fluorohexyl group, and the like.
Examples of the cyclic saturated aliphatic hydrocarbon group having 5 to 6 carbon atoms in which one or more hydrogen atoms are substituted with a fluorine atom include a fluorocyclopentyl group and a fluorocyclohexyl group.
Examples of the aromatic hydrocarbon group in which one or more hydrogen atoms have been replaced by fluorine atoms include a fluorophenyl group, a difluorophenyl group, and a trifluorophenyl group.
Examples of the heterocyclic group having 4 to 6 carbon atoms in which one or more hydrogen atoms are substituted with a fluorine atom include a fluorothienyl group, a fluorofuranyl group, a fluoropyridyl group, a fluorothiolanyl group, a fluorooxanyl group, a fluorooxanyl group, And a piperidyl group.
R ^{3 to} R ⁷ are preferably a hydrogen atom, a methyl group or a vinyl group, and a hydrogen atom, since excellent battery characteristics such as good cycle characteristics, high safety and storage stability are obtained. Is more preferable.

The hydrocarbon group having 1 to 6 carbon atoms in R ^{8 to} R ¹⁰ in the general formula (2) is the same as the hydrocarbon group having 1 to 6 carbon atoms in R ¹ and R ² in the general formula (1). Is mentioned.
Examples of the alkoxy group having 1 to 6 carbon atoms in R ^{8 to} R ¹⁰ in the general formula (2) 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 cyclohexyl group. And a siloxy group.
R ^{8 to} R ¹⁰ are preferably a methyl group, a vinyl group or a phenyl group, and more preferably a methyl group, since excellent battery characteristics can be obtained.

As a specific example of the compound represented by the general formula (2), when R ^{8 to} R ¹⁰ are a methyl group, for example, the following compound No. 2-1 to No. 2-75, but is not limited thereto.

As a specific example of the compound represented by the general formula (2), when R ^{3 to} R ⁷ are hydrogen atoms, for example, the following compound No. 2-76-No. 2-142, but not limited thereto.

  The composition of the present invention contains at least one compound represented by the general formula (1) and at least one compound represented by the general formula (2). The content of the compound represented by the general formula (1) is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 10% by mass, and 0.1% by mass to 5% by mass. More preferably, it is. Further, the content of the compound represented by the general formula (2) is preferably 0.01% by mass to 10% by mass, more preferably 0.05% by mass to 10% by mass, and 0.1% by mass to 5% by mass. % Is more preferable. When the content of these compounds is less than the above range, the effect of improving the characteristics of the nonaqueous electrolyte secondary battery having the composition of the present invention may not be sufficient. This is because a suitable effect cannot be obtained, which may adversely affect battery characteristics.

  The mass ratio of the compound represented by the general formula (2) to the compound represented by the general formula (1) is such that excellent battery characteristics such as good cycle characteristics, high safety and storage stability can be obtained. , Preferably from 0.01 to 100, more preferably from 0.1 to 50, even more preferably from 0.2 to 10.

The composition of the present invention further includes a lithium salt and a solvent and / or a dispersion medium.
The form of the composition of the present invention is not particularly limited, and an organic solvent is used as a solvent, a liquid composition obtained by dissolving a lithium salt, a solvent or a dispersion medium, and a polymer compound is dissolved in an organic solvent. Using a gelled polymer gel, a polymer gel composition obtained by dissolving or dispersing a lithium salt, a polymer as a dispersion medium, and a pure polymer composition obtained by dispersing a lithium salt Can be used.

As the lithium salt used in the liquid composition and the polymer gel composition, a conventionally known lithium salt, 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. Among these, 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 (SO ₂ F) ₂ , LiPO ₂ F ₂ , LiC (CF ₃ SO ₂ ) ₃ , and one or more selected from the group consisting of a derivative of LiCF ₃ SO _{3 and} a derivative of LiC (CF ₃ SO ₂ ) ₃ .

Examples of the lithium salt used in the pure polymer composition include LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (SO ₂ F) ₂ , and LiC (CF ₃ SO ₂ ). ₃ , LiB (CF ₃ SO ₃ ) ₄ , LiB (C ₂ O ₄ ) _{2 and the} like.

  If the concentration of the lithium salt in the composition is too low, a sufficient current density may not be obtained, and if the concentration is too high, the stability of the liquid nonaqueous electrolyte may be impaired. ７7 mol / L is preferred, and 0.8-1.8 mol / L is more preferred. Lithium salts can be used in combination of two or more.

  As the organic solvent used for the liquid composition and the polymer gel composition, an organic solvent usually used for a non-aqueous electrolyte of a non-aqueous electrolyte secondary battery can be used. Examples of the organic solvent usually used for the non-aqueous electrolyte of the non-aqueous electrolyte secondary battery include, for example, a saturated cyclic carbonate compound, a saturated cyclic ester compound, a sulfoxide compound, a sulfone compound, an amide compound, a saturated chain carbonate compound, and a chain ether. Compounds, cyclic ether compounds, saturated chain ester compounds and the like. The organic solvent can be used alone or in combination of two or more.

Among the organic solvents, a saturated cyclic carbonate compound, a saturated cyclic ester compound, a sulfoxide compound, a sulfone compound and an amide compound have a high relative dielectric constant, and thus play a role of increasing the dielectric constant of the liquid composition, and in particular, a saturated cyclic carbonate compound. Is preferred.
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, 1,1-dimethylethylene carbonate, and the like. Can 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, and thiophene.
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-diphenylsulfolane, sulfolene, Examples thereof include 3-methylsulfolene, 3-ethylsulfolene, and 3-bromomethylsulfolene, and sulfolane and tetramethylsulfolane are preferable.
Amide compounds include N-methylpyrrolidone, dimethylformamide, dimethylacetamide and the like.

Among the organic solvents, the saturated chain carbonate compound, the chain ether compound, the cyclic ether compound and the saturated chain ester compound can lower the viscosity of the liquid composition and increase the mobility of electrolyte ions. For example, the battery characteristics such as the output density can be improved. Further, since the viscosity is low, the performance of the non-aqueous electrolyte at a low temperature can be enhanced, and a saturated chain carbonate compound is particularly preferable.
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 or the cyclic ether compound include dimethoxyethane, ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolan, dioxane, 1,2-bis (methoxycarbonyloxy) ethane, and 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 Fluorooxo) ether and the like, and among these, dioxolan is preferable.
As the saturated chain ester compound, a monoester compound and a diester compound having a total of 2 to 8 carbon atoms in the molecule are preferable. Specific examples of the compound include methyl formate, ethyl formate, methyl acetate, and acetic acid. Ethyl, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate, methyl malonate, ethyl malonate, methyl succinate, ethyl succinate, Examples thereof include methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetyl, and propylene glycol diacetyl. Among them, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, and butyl acetate ,Professional Methyl propionic acid, and ethyl propionate are preferred.

  In addition, as the organic solvent, for example, acetonitrile, propionitrile, nitromethane, derivatives thereof, and various ionic liquids can be used.

Examples of the polymer compound used in the polymer gel composition include polyethylene oxide, polypropylene oxide, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, polyethylene, polyvinylidene fluoride, and polyhexafluoropropylene.
Examples of the polymer compound used in the pure polymer composition include polyethylene oxide, polypropylene oxide, and polystyrene sulfonic acid.
There is no particular limitation on the mixing ratio of each component of the polymer gel composition and the pure polymer composition, and the method of compounding, and a compounding ratio known in the art and a known compounding method can be employed.

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

<Non-aqueous electrolyte>
The non-aqueous electrolyte of the present invention uses the above-described composition, and in order to improve battery life, improve safety, etc., known electrolytes such as an electrode film forming agent, an antioxidant, a flame retardant, and an overcharge preventing agent. It may contain additives. If the concentration of the electrolyte additive is low, the effect of the addition cannot be exhibited if the concentration is low, and if the concentration is too high, the characteristics of the nonaqueous electrolyte secondary battery may be adversely affected. 0.01% by mass to 10% by mass is preferable, and 0.1% by mass to 5% by mass is more preferable.

<Non-aqueous electrolyte secondary battery>
A nonaqueous electrolyte secondary battery of the present invention includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and the nonaqueous 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.

(Positive electrode)
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 additive is coated with an electrode mixture paste slurried with an organic solvent or water on a current collector and dried to form an electrode mixture on the current collector. A positive electrode having a layer formed thereon can be manufactured.

Known positive electrode active materials can be used. Known positive electrode active materials include, for example, lithium transition metal composite oxides, lithium-containing transition metal phosphate compounds, lithium-containing silicate compounds, and lithium-containing transition metal sulfate compounds. The transition metal of the lithium transition metal composite oxide is preferably vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, or the like.
Specific examples of the lithium transition metal composite oxide include a lithium cobalt composite oxide such as LiCoO ₂ , a lithium nickel composite oxide such as LiNiO ₂ , and a lithium manganese composite oxide such as LiMnO ₂ , LiMn ₂ O ₄ , and Li ₂ MnO _3. Products, some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are converted to aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, etc. Examples thereof include those substituted with another metal. Examples of the lithium transition metal composite oxide in which part of the main transition metal atom is substituted with another metal include, for example, Li _1.1 Mn _1.8 Mg _0.1 O ₄ and 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 _{0.5 . 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, for example, LiFePO ₄ , LiMn _x Fe _1-x PO ₄ (M = Co , Ni, Mn), cobalt phosphate compounds such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are converted to aluminum, titanium, vanadium, chromium, Substitution with other metals such as manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, and niobium, and vanadium phosphate compounds such as Li ₃ V ₂ (PO ₄ ) _{3 and the} like. Can be
Examples of the lithium-containing silicate compound include Li ₂ FeSiO _{4 and the} like.
Examples of the lithium-containing transition metal sulfate compound include LiFeSO ₄ and LiFeSO ₄ F.
These can be used alone or in combination of two or more.

As the positive electrode active material, a sulfur-modified organic compound can be used. The sulfur-modified organic compound is a mixture of sulfur, polyacrylonitrile compound, elastomer compound, pitch compound, polynuclear aromatic ring compound, aliphatic hydrocarbon oxide, polyether compound, polythienoacene compound, polyamide compound, hexachlorobutadiene, etc. It can be manufactured by heat denaturation at 250 ° C. to 600 ° C. in an inert gas atmosphere.
Further, a sulfur-carbon composite can be used as the positive electrode active material. The sulfur-carbon composite contains elemental sulfur in the pores of porous carbon and can absorb and release lithium ions and can be used as an electrode active material of a secondary battery. The sulfur content of the sulfur-carbon composite in which elemental sulfur is supported in the pores of the porous carbon is such that if the content is too small, the charge / discharge capacity does not increase, and too much electron conductivity is reduced. It is preferably from 80% by mass to 80% by mass, and more preferably from 30% by mass to 70% by mass. A known method can be adopted as a method of supporting elemental sulfur in the pores of the porous carbon.

  The sulfur content of 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, a uniform and smooth electrode mixture layer may not be obtained, and if the particle size is too small, the handling property in the slurrying process is reduced. D50) is preferably from 0.5 μm to 100 μm, more preferably from 1 μm to 50 μm, even more preferably from 1 μm to 30 μm.
In the present invention, the average particle diameter (D50) refers to a 50% particle diameter measured by a laser diffraction light scattering method. The particle diameter is a volume-based diameter, and the diameter of the secondary particles is measured by the laser diffraction light scattering method.
The positive electrode active material can have a desired particle size by a method such as pulverization. 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, a bead mill, and the like.

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, polyamide, polyamideimide, polyimide, polyacrylonitrile, Polyurethane, polyvinylidene fluoride, polytetrafluoroethylene, styrene-acrylate copolymer, ethylene-vinyl alcohol copolymer, polymethyl methacrylate, polyacrylate, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl ether, polyvinyl chloride , Polyacrylic acid, methylcellulose, carboxymethylcellulose, carboxymethylcellulose sodium, Loin nanofibers, and starch.
Only one binder may be used, or two or more binders may be used in combination.
The content of the binder is preferably from 1 to 30 parts by mass, more preferably from 1 to 20 parts by mass, per 100 parts by mass of the positive electrode active material.

As the conductive assistant, a known conductive assistant for an electrode can be used. Specifically, for example, natural graphite, artificial graphite, coal tar pitch, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon nanotube, vapor grown carbon fiber (Vapor Crown) (Carbon Fiber: VGCF), carbon materials such as graphene, fullerene, and needle coke; metal powders such as aluminum powder, nickel powder, and titanium powder; conductive metal oxides such as zinc oxide and titanium oxide; La ₂ S ₃ , Sm ₂ Sulfides such as S ₃ , Ce ₂ S ₃ , and TiS ₂ are exemplified.
The particle size of the conductive additive is preferably from 0.0001 μm to 100 μm, more preferably from 0.01 μm to 50 μm.
The content of the conductive additive is generally 0.1 to 50 parts by mass, preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, based on 100 parts by mass of the electrode active material.

  As a solvent for preparing the electrode mixture paste, for example, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, acetonitrile, propionitrile , Tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, 1,3-dioxolan, nitromethane, N-methylpyrrolidone, N, N-dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N -Dimethylaminopropylamine, polyethylene oxide, tetrahydrofuran, dimethyl sulfoxide, sulfolane, γ-butyrolactone, water, alcohol, etc. It is below. The amount of the solvent used can be adjusted according to the method selected when coating the slurry. For example, in the case of application by the doctor blade method, the total amount of the positive electrode active material, the binder and the conductive additive is 100 parts by mass. Is preferably from 15 to 300 parts by mass, more preferably from 30 to 200 parts by mass.

  The electrode mixture paste, in a range that does not impair the effects of the present invention, in addition to the above-described components, for example, contains other components such as a viscosity modifier, a reinforcing material, an antioxidant, a pH regulator, and a dispersant. Is also good. As these other components, known components can be used in a known blending ratio.

When dispersing or dissolving the positive electrode active material, the binder and the conductive auxiliary in a solvent in the production of the electrode mixture paste, all can be added to the solvent at once and subjected to dispersion treatment, and separately added and dispersed. You can also. It is preferable to sequentially add the binder, the conductive auxiliary agent, and the positive electrode active material to the solvent in the order of the dispersion treatment, since these can be uniformly dispersed in the solvent.
When the electrode mixture paste contains other components, the other components can be added at once and subjected to a dispersion treatment. However, it is preferable to perform the dispersion treatment every time one kind is added.

  The method of the dispersion treatment is not particularly limited, but as an industrial method, for example, a normal ball mill, a sand mill, a bead mill, a cyclone mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a rotation / revolution mixer, Planetary mixers, fill mixes, jet pasters and the like can be used.

  As the current collector, a conductive material such as titanium, a titanium alloy, aluminum, an aluminum alloy, nickel, stainless steel, nickel-plated steel, and carbon is used. Examples of the shape of the current collector include a foil shape, a plate shape, and a net shape, and the current collector may be either porous or non-porous. Further, these conductive materials may be subjected to surface treatment in order to improve adhesion and electric characteristics. Among these conductive materials, aluminum is preferred from the viewpoint of conductivity and price, and aluminum foil is particularly preferred. The thickness of the current collector is not particularly limited, but is usually 5 to 30 μm.

  The method of applying the electrode mixture paste to the current collector is not particularly limited. For example, a die coater method, a comma coater method, a curtain coater method, a spray coater method, a gravure coater method, a flexo coater method, a knife coater method, a doctor coater method Each method such as a blade method, a reverse roll method, a brush coating method, and a dip method 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 drying property of the electrode mixture paste.

  The application of the electrode mixture paste to the current collector can be performed on one side or both sides of the current collector. In the case of coating on both sides of the current collector, it is possible to sequentially apply one side at a time, or to apply both sides simultaneously. Further, it can be applied continuously to the surface of the current collector, can be applied intermittently, or can be applied in a stripe shape. 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 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, low-humidity air, vacuum drying, standing in a heating furnace or the like, and drying by irradiating far infrared rays, infrared rays, electron beams, or the like. These can be implemented in combination. The temperature in the case of heating is, for example, generally about 50 ° C. to 180 ° C., but conditions such as the temperature can be appropriately set according to the application amount of the slurry composition, the boiling point of the solvent used, and the like. . By this drying, volatile components such as a solvent are volatilized from the coating film of the electrode mixture paste, and an electrode mixture layer is formed on the current collector.

  When using a sulfur-modified organic compound, and a sulfur-carbon composite as the positive electrode active material, after preparing a positive electrode containing the sulfur-modified organic compound, and the sulfur-carbon composite, or the sulfur-modified organic compound, and the sulfur-carbon composite Alternatively, lithium can be pre-doped and used. The method of pre-doping may follow a known method. For example, assembling a half-cell using metallic lithium as the counter electrode and inserting lithium by electrolytic doping method of electrochemically doping lithium, or attaching a metallic lithium foil to the electrode and leaving it in the electrolytic solution There is a method of inserting lithium by a sticking pre-doping method of doping utilizing diffusion of lithium to an electrode, a mechanical method of mechanically colliding an active material with lithium metal and inserting lithium, and the like, but is not limited thereto. Not to be done.

(Negative electrode)
The negative electrode used in the present invention can be manufactured according to a known method. For example, by applying a mixture containing a negative electrode active material, a binder and a conductive additive to a current collector by slurrying an electrode mixture paste with an organic solvent or water, and drying the mixture, the electrode mixture is formed on the current collector. A negative electrode provided with a layer can be manufactured.

Known negative electrode active materials can be used. Known negative electrode active materials include, for example, natural graphite, artificial graphite, non-graphitizable carbon, easily 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 and a composite oxide such as a titanium-niobium-based oxide may be used. These can be used alone or in combination of two or more.

  As the negative electrode active material, a sulfur-modified organic compound can be used. The sulfur-modified organic compound is a mixture of sulfur, polyacrylonitrile compound, elastomer compound, pitch compound, polynuclear aromatic ring compound, aliphatic hydrocarbon oxide, polyether compound, polythienoacene compound, polyamide compound, hexachlorobutadiene, etc. It can be manufactured by heat denaturation at 250 ° C. to 600 ° C. in an inert gas atmosphere. The non-oxidizing atmosphere is an atmosphere having 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 an inert gas such as nitrogen, helium, or argon; It is a sulfur gas atmosphere.

If the particle size of the negative electrode active material is too large, a uniform and smooth electrode mixture layer may not be obtained, and if the particle size is too small, the handling property in the slurrying process is reduced. D50) is preferably from 0.05 μm to 100 μm, more preferably from 1 μm to 50 μm, even more preferably from 1 μm to 30 μm.
The negative electrode active material can have a desired particle size by a method such as pulverization. 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, a bead mill, and the like.

Known binders can be used. Specific examples of the binder include those similar to the binder used for the positive electrode.
Only one binder may be used, or two or more binders may be used in combination.
The content of the binder is preferably from 1 to 30 parts by mass, more preferably from 1 to 20 parts by mass, per 100 parts by mass of the negative electrode active material.

As the conductive assistant, a known conductive assistant for an electrode can be used. Specifically, the same as the conductive additive used for the positive electrode can be used.
The particle size of the conductive additive is preferably from 0.0001 μm to 100 μm, more preferably from 0.01 μm to 50 μm.
The content of the conductive additive is usually 0 to 50 parts by mass, preferably 0.5 to 30 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the electrode active material.

  Examples of the solvent for preparing the electrode mixture paste include the same solvents as those used for preparing the electrode mixture paste for the positive electrode. The amount of the solvent used can be adjusted according to the method selected when coating the slurry. For example, in the case of application by the doctor blade method, the total amount of the negative electrode active material, the binder and the conductive auxiliary agent is 100 parts by mass. Is preferably from 15 to 300 parts by mass, more preferably from 30 to 200 parts by mass.

  The electrode mixture paste, in a range that does not impair the effects of the present invention, in addition to the above-described components, for example, contains other components such as a viscosity modifier, a reinforcing material, an antioxidant, a pH regulator, and a dispersant. Is also good. As these other components, known components can be used in a known blending ratio.

  Except for using the negative electrode active material instead of the positive electrode active material, the production of the electrode mixture paste can be performed by blending, dispersing, and producing the same steps as the production process of the positive electrode mixture paste.

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

  When the negative electrode active material is a metal or metal alloy such as lithium, lithium alloy, tin, and 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, plate-shaped. , A sheet, a film, or the like. When the alloy is used as the negative electrode active material, the current collector does not have to be used because the electron conductivity of the negative electrode active material itself is high. However, depending on the configuration of the battery, an alloy with the negative electrode active material may be formed. A metal material not used can be used as the negative electrode current collector.

(Separator)
In the nonaqueous electrolyte secondary battery of the present invention, it is preferable to use a separator between the positive electrode and the negative electrode. As the separator, a commonly used polymer film can be used without particular limitation. As the film, for example, polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, polyethylene oxide and polypropylene oxide Films composed of ethers, various celluloses such as carboxymethylcellulose and hydroxypropylcellulose, high molecular compounds mainly composed of poly (meth) acrylic acid and various esters thereof, derivatives thereof, and copolymers and mixtures thereof. These films may be coated with a ceramic material such as alumina or silica, magnesium oxide, an aramid resin, or polyvinylidene fluoride. That.
These films can be used alone, and can be used as a multilayer film by laminating these films. Furthermore, various additives can be used for these films, and the types and contents thereof are not particularly limited. Among these films, films made of polyethylene, polypropylene, polyvinylidene fluoride, and polysulfone are preferably used.

  These films are microporous so that the electrolyte penetrates and ions easily permeate. There are two methods of microporous formation: a phase separation method, in which a solution of a polymer compound and a solvent is microphase-separated to form a film, and the solvent is extracted and removed to form a porous layer. The film is extruded to form a film, and then heat-treated to arrange the crystals in one direction. Further, a "stretching method" for forming a gap between the crystals by stretching to make the crystals porous, and the like are appropriately selected depending on the film to be used.

(External packaging)
The shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited, and can be batteries of various shapes such as a coin battery, a cylindrical battery, a square battery, and a laminated battery. Can be used as a metal container or a laminated film. The thickness of the outer packaging member is usually 0.5 mm or less, preferably 0.3 mm or less. Examples of the shape of the external packaging 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 from, 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. In aluminum or an aluminum alloy, by setting the content of transition metals such as iron, copper, nickel, and chromium to 1% or less, long-term reliability and heat dissipation under 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, or polyethylene terephthalate can be used. The laminate film can be sealed by heat fusion to form an exterior member.

  FIG. 1 shows an example of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention, FIGS. 2 and 3 show examples of a cylindrical battery, and FIGS. 4 to 6 show examples of a laminated battery. is there.

  In the coin-type nonaqueous electrolyte secondary battery 10 shown in FIG. 1, 1 is a positive electrode capable of releasing lithium ions, 1a is a positive electrode current collector, 2 is a negative electrode capable of absorbing and releasing lithium ions released from the positive electrode, and 2a is a negative electrode. A current collector, 3 is a non-aqueous electrolyte, 4 is a stainless steel positive electrode case, 5 is a stainless steel negative electrode case, 6 is a polypropylene gasket, and 7 is a polyethylene separator.

  In the cylindrical nonaqueous electrolyte secondary battery 10 'shown in FIGS. 2 and 3, 11 is a negative electrode, 12 is a negative electrode current collector, 13 is a positive electrode, 14 is a positive electrode current collector, 15 is a nonaqueous electrolyte, and 16 is a separator. , 17 is a positive electrode terminal, 18 is a negative electrode terminal, 19 is a negative electrode plate, 20 is a negative electrode lead, 21 is a positive electrode plate, 22 is a positive electrode lead, 23 is a case, 24 is an insulating plate, 25 is a gasket, 26 is a safety valve, 27 is It is a PTC element.

  FIG. 4 is an exploded perspective view schematically showing the electrode group 29 of the laminated nonaqueous electrolyte secondary battery 28. In the examples described below, a laminate type nonaqueous electrolyte secondary battery will be described, but the present invention is not limited to this. The electrode group 29 has, for example, a structure in which a sheet-like negative electrode 11, a sheet-like positive electrode 13, and a sheet-like separator 16 separating the negative electrode 11 and the positive electrode 13 are alternately stacked. Reference numeral 17 denotes a positive terminal, and reference numeral 18 denotes a negative terminal.

  FIG. 5 is an exploded perspective view schematically illustrating the laminated nonaqueous electrolyte secondary battery 28, and FIG. 6 is an external plan view schematically illustrating the laminated nonaqueous electrolyte secondary battery 28. Reference numeral 17 denotes a positive terminal, 18 denotes a negative terminal, 29 denotes an electrode group, 30 denotes a case-side laminate film, and 31 denotes a lid-side laminate film.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. The present invention can be implemented in various forms with modifications, improvements, and the like that can be made by those skilled in the art without departing from the gist of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited at all by the following examples. In the examples, "parts" and "%" are based on mass unless otherwise specified. The sulfur content of the sulfur-porous carbon composite and the sulfur-modified organic compound was calculated by performing an elemental analysis using a CHN analyzer (Varier MICRO cube, an elementator) capable of analyzing sulfur and oxygen.

<Preparation of positive electrode A>
90.0 parts by mass of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as a positive electrode active material, 5.0 parts by mass of acetylene black (manufactured by Denka) as a conductive aid, and polyvinylidene fluoride (Kureha) as a binder Was used and 5.0 parts by mass of N-methylpyrrolidone was used as a solvent, and the mixture was dispersed using a rotation / revolution mixer to obtain a slurry electrode mixture paste. This electrode mixture paste was applied to both surfaces of a current collector made of aluminum foil (thickness: 20 μm) by a doctor blade method, dried at 90 ° C., and press-molded. Thereafter, the electrode was cut into a predetermined size, and further vacuum-dried at 150 ° C. for 24 hours immediately before use to prepare a positive electrode A.

<Preparation of positive electrode B>
Using a mortar, 10.0 parts by mass of polyacrylonitrile powder (manufactured by Sigma-Aldrich Corporation) and 30.0 parts by mass of sulfur powder (manufactured by Sigma-Aldrich Company, average particle diameter 200 μm) classified with a sieve having an opening diameter of 30 μm were mixed. With reference to the examples of JP-A-2013-054957, this mixture was placed in a bottomed cylindrical glass tube, and then the lower portion of the glass tube was placed in a crucible-type electric furnace to remove hydrogen sulfide generated under a nitrogen stream. While heating at 400 ° C. for 1 hour. After cooling, the product was placed in a glass tube oven and heated at 250 ° C. for 3 hours while vacuum suctioning to remove elemental sulfur. The obtained sulfur-modified product was pulverized using a ball mill and classified by a sieve to obtain sulfur-modified polyacrylonitrile (PANS) having an average particle diameter of 10 μm. The sulfur content of PANS was 38.4% by mass.
92.0 parts by mass of PANS as a positive electrode active material, 5.0 parts by mass of acetylene black (manufactured by Denka) as a conductive aid, and styrene-butadiene rubber (40 mass% aqueous dispersion, manufactured by Zeon Corporation) as a binder 1.5 parts by mass of sodium carboxymethylcellulose (CMCNa: manufactured by Daicel FineChem) and 120 parts by mass of water as a solvent are dispersed using a rotation / revolution mixer to form a slurry electrode mixture. A paste was obtained. This electrode mixture paste was applied to both surfaces of a current collector made of carbon-coated aluminum foil (thickness: 22 μm) by a doctor blade method, dried at 90 ° C., and press-molded. Thereafter, the electrode was cut into a predetermined size, and further vacuum dried at 150 ° C. for 24 hours immediately before use to prepare a positive electrode B.

<Preparation of negative electrode>
96.0 parts by mass of artificial graphite (MAG: manufactured by Hitachi Chemical Co., Ltd.) as a negative electrode active material, 1.0 part by mass of acetylene black (manufactured by Denka) as a conductive aid, and styrene-butadiene rubber (40% by mass water) as a binder Dispersion, 1.5 parts by mass of ZEON Corporation, 1.5 parts by mass of sodium carboxymethylcellulose (CMCNa: manufactured by Daicel Finechem), 120 parts by mass of water as a solvent, and a rotation / revolution mixer. The resultant was dispersed to obtain a slurry-like electrode mixture paste. This electrode mixture paste was applied to both surfaces of a current collector made of copper foil by a doctor blade method, dried at 90 ° C., and press-molded. Thereafter, the electrode was cut into a predetermined size, and immediately before use, vacuum-dried at 150 ° C. for 24 hours to prepare a negative electrode.

<Example 1>
In a mixed solvent composed of 50% by volume of ethylene carbonate and 50% by volume of diethyl carbonate, 1.0 mol / L of LiPF ₆ was added. 1-1 in an amount of 1.0% by mass. A composition in which 2-1 was dissolved at a concentration of 2.0% by mass was prepared and used as a non-aqueous electrolyte.
The positive electrode A and the negative electrode were stacked with a separator (Celgard 2325, manufactured by Celgard) interposed therebetween, and a positive electrode terminal and a negative electrode terminal were provided for the positive electrode and the negative electrode, respectively, to obtain an electrode group. The obtained electrode group and the non-aqueous electrolyte were accommodated in a case made of a laminated film and sealed, whereby a laminated non-aqueous electrolyte secondary battery of Example 1 was produced. The capacity of the battery is 0.1 Ah. FIGS. 4 to 6 show schematic diagrams of the laminated nonaqueous electrolyte secondary battery manufactured in this example.

<Example 2>
Except that Compound No. 1-1 was dissolved at a concentration of 2.0% by mass and Compound 2-1 was dissolved at a concentration of 1.0% by mass, the same procedure as in Example 1 was repeated except that the laminated nonaqueous electrolyte secondary of Example 2 was used. A battery was manufactured.

<Example 3>
Compound No. A laminated nonaqueous electrolyte secondary battery of Example 3 was produced in the same manner as in Example 1, except that the compound 1-1 was dissolved at a concentration of 2.0% by mass and the compound 2-1 was dissolved at a concentration of 0.5% by mass. did.

<Comparative Example 1>
From the non-aqueous electrolyte of Example 1, Compound No. A laminated nonaqueous electrolyte secondary battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the addition of 1-1 was omitted.

<Comparative Example 2>
From the non-aqueous electrolyte of Example 1, Compound No. A laminated nonaqueous electrolyte secondary battery of Comparative Example 2 was produced in the same manner as in Example 1 except that the addition of 2-1 was omitted.

<Comparative Example 3>
From the non-aqueous electrolyte of Example 1, Compound No. 1-1 and Compound No. A laminated nonaqueous electrolyte secondary battery of Comparative Example 3 was produced in the same manner as in Example 1 except that the addition of 2-1 was omitted.

<Example 4>
A laminated nonaqueous electrolyte secondary battery of Example 4 was produced in the same manner as in Example 1, except that the positive electrode B was used as the positive electrode. As the positive electrode B, a half-cell was assembled in advance using metallic lithium as a counter electrode, and lithium electrochemically doped was used.

<Comparative Example 4>
A laminated nonaqueous electrolyte secondary battery of Comparative Example 4 was produced in the same manner as in Comparative Example 1, except that the positive electrode B was used as the positive electrode.

<Comparative Example 5>
A laminated nonaqueous electrolyte secondary battery of Comparative Example 5 was produced in the same manner as in Comparative Example 2, except that the positive electrode B was used as the positive electrode.

<Comparative Example 6>
A laminated nonaqueous electrolyte secondary battery of Comparative Example 6 was produced in the same manner as in Comparative Example 3, except that the positive electrode B was used as the positive electrode.

<Example 5>
Compound No. 1-1 was replaced with Compound No. 1-1. A laminated nonaqueous electrolyte secondary battery of Example 5 was produced in the same manner as in Example 1 except that 1-74 was used.

<Comparative Example 7>
From the non-aqueous electrolyte of Example 5, Compound No. A laminated nonaqueous electrolyte secondary battery of Comparative Example 7 was produced in the same manner as in Example 5 except that the addition of 2-1 was omitted.

<Example 6>
Compound No. Compound No. 2-1 was used instead of Compound No. A laminated nonaqueous electrolyte secondary battery of Example 6 was made in the same manner as Example 1 except that 2-99 was used.

<Comparative Example 8>
From the non-aqueous electrolyte of Example 6, Compound No. A laminated nonaqueous electrolyte secondary battery of Comparative Example 8 was produced in the same manner as in Example 6, except that the addition of 1-1 was omitted.

<Charge / Discharge evaluation A>
The laminated non-aqueous electrolyte secondary batteries of Examples 1 to 3, 5 and 6 and Comparative Examples 1 to 3, 7 and 8 were placed in a thermostat at 30 ° C., and the charge end voltage was 4.3 V and the discharge end voltage was A charge / discharge test at 3.0 V and a charge rate of 0.2 C and a discharge rate of 0.2 C was performed for 5 cycles. Thereafter, a charge / discharge test at a charge rate of 1.0 C and a discharge rate of 1.0 C was performed for 300 cycles. Table 1 shows the ratio of the discharge capacity at the 300th cycle and the discharge capacity at the 5th cycle at 1.0 C as a capacity retention ratio.
(Capacity maintenance rate = discharge capacity at 300th cycle / discharge capacity at 5th cycle × 100)

<Charging / discharging evaluation B>
The laminated non-aqueous electrolyte secondary batteries of Example 4 and Comparative Examples 4 to 6 were placed in a thermostat at 30 ° C., the charge end voltage was set to 3.0 V, the discharge end voltage was set to 0.5 V, and the charge rate was 0.2 C. A charge / discharge test at a discharge rate of 0.2 C was performed for 5 cycles. Thereafter, a charge / discharge test at a charge rate of 1.0 C and a discharge rate of 1.0 C was performed for 300 cycles. Table 1 shows the ratio of the discharge capacity at the 300th cycle and the discharge capacity at the 5th cycle at 1.0 C as a capacity retention ratio.
(Capacity maintenance rate = discharge capacity at 300th cycle / discharge capacity at 5th cycle × 100)

<Storage test>
The produced laminated nonaqueous electrolyte secondary battery was stored at 30 ° C. for 10 days, and Examples 1-3, 5 and 6 and Comparative Examples 1-3, 7 and 8 were subjected to charge / discharge test A, Example 4 and Comparative In Examples 4 to 6, the same evaluation as in the discharge test B was performed. The storage stability was defined as the ratio of the discharge capacity at the 300th cycle measured after storage for 10 days to the discharge capacity at the 300th cycle measured immediately after the production of the laminated nonaqueous electrolyte secondary battery.
(Storage stability = discharge capacity at the 300th cycle of the nonaqueous electrolyte secondary battery after storage for 10 days 日 discharge capacity at the 300th cycle of the nonaqueous electrolyte secondary battery immediately after fabrication × 100)

<Evaluation of battery swelling>
Regarding the laminated nonaqueous electrolyte secondary battery after the charge / discharge test, the degree of swelling of the battery was visually examined. When no swelling was observed, the symbol 〇, when slight swelling was observed, △, and when significant swelling was noted, ×.

  As shown in Table 1, Examples 1 to 6 had higher capacity retention rates than Comparative Examples 1 to 8, were excellent in storage stability, and had high safety without causing battery swelling. Was.

REFERENCE SIGNS LIST 1 positive electrode 1 a positive electrode current collector 2 negative electrode 2 a negative electrode current collector 3 nonaqueous electrolyte 4 positive electrode case 5 negative electrode case 6 gasket 7 separator 10 coin-type nonaqueous electrolyte secondary battery 10 ′ cylindrical nonaqueous electrolyte secondary battery 11 negative electrode 12 Negative electrode current collector 13 Positive electrode 14 Positive electrode current collector 15 Nonaqueous electrolyte 16 Separator 17 Positive terminal 18 Negative terminal
19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode plate 22 Positive electrode lead 23 Case 24 Insulating plate 25 Gasket 26 Safety valve 27 PTC element 28 Laminated non-aqueous electrolyte secondary battery 29 Electrode group 30 Case-side laminate film 31 Lid-side laminate film

Claims (9)

A composition comprising a compound represented by the following general formula (1), a compound represented by the following general formula (2), a lithium salt, and a solvent and / or a dispersion medium.
(Wherein, R ¹ and R ² are each independently a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a heterocyclic group having 4 to 6 carbon atoms, and at least one hydrogen atom is a halogen atom. Represents a substituted hydrocarbon group having 1 to 6 carbon atoms or a heterocyclic group having 4 to 6 carbon atoms in which at least one hydrogen atom is substituted by a halogen atom.)
(Wherein, R ^{3 to} R ⁷ each independently represent a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, a heterocyclic group having 4 to 6 carbon atoms, and at least one hydrogen atom Represents a hydrocarbon group having 1 to 6 carbon atoms substituted with a fluorine atom, or a heterocyclic group having 4 to 6 carbon atoms substituted with one or more hydrogen atoms with a fluorine atom,
R ^{8 to} R ¹⁰ each independently represent a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms. )   The composition according to claim 1, comprising a compound represented by the general formula (1), a compound represented by the general formula (2), a lithium salt, and a solvent.   The concentration of the compound represented by the general formula (1) is from 0.01% by mass to 10% by mass, and the concentration of the compound represented by the general formula (2) is from 0.01% by mass to 10% by mass. 3. The composition according to 1 or 2.   The composition according to any one of claims 1 to 3, wherein a mass ratio of the compound represented by the general formula (2) to the compound represented by the general formula (1) is 0.01 to 100. . The composition according to any one of claims 1 to 4, wherein R ¹ and R ² of the compound represented by the general formula (1) are each independently a hydrogen atom, a methyl group, a vinyl group, or a phenyl group. . The compound represented by the general formula (2), wherein R ^{3 to} R ⁷ are a hydrogen atom, and R ^{8 to} R ¹⁰ are each independently a methyl group, an ethyl group, a vinyl group or a phenyl group. The composition according to any one of claims 1 to 5.   A non-aqueous electrolyte using the composition according to claim 1.   A non-aqueous electrolyte secondary battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and the non-aqueous electrolyte according to claim 7. The non-aqueous electrolyte secondary battery according to claim 8, which is a laminated battery.