Nonaqueous electrolyte solution for secondary battery, lithium ion battery, and lithium ion capacitor

Abstract

A nonaqueous electrolyte solution for a secondary battery, which contains a first compound represented by formula (1), a second compound, a nonaqueous solvent and an electrolyte, and wherein the second compound is at least one compound selected from the group consisting of a compound represented by formula (2), a compound represented by formula (3) and a compound represented by formula (4). # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a non-aqueous electrolyte for a secondary battery, a lithium ion battery and a lithium ion capacitor. Background Art

[0002] The use of electrolytes to which various additives are added in lithium-ion batteries has been studied. When the electrolyte contains additives, the additives are sometimes decomposed during the initial charge and discharge, and a film called a solid electrolyte interface (SEI) is formed on the electrode surface. By forming such an SEI, it helps to prevent the degradation of storage devices such as non-aqueous electrolyte secondary batteries during repeated charge and discharge cycles, improve battery performance, etc.

[0003] For example, Patent Document 1 describes a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte to which one of monofluoro lithium phosphate and difluoro lithium phosphate is added as an additive. Patent Document 2 describes an additive for a non-aqueous electrolyte comprising a specific cyclic sulfone compound having an alkylene carbonyloxy group or a sulfonyloxy group. Patent Document 3 describes an electrolyte for an electrochemical device in which an electrolyte comprising a specific ionic metal complex is dissolved in a non-aqueous solvent.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 11-67270

[0007] Patent Document 2: International Publication No. 2017 / 043576

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2004-146071 Summary of the invention

[0009] Technical issues to be solved by the invention

[0010] The present invention relates to a non-aqueous electrolyte solution capable of improving the high-temperature storage characteristics of a secondary battery.

[0011] Means for solving technical problems

[0012] The present invention provides the following [1] to

[11] in several aspects.

[0013] [1] A non-aqueous electrolyte for a secondary battery, comprising a first compound represented by the following formula (1), a second compound, a non-aqueous solvent, and an electrolyte, wherein the second compound is at least one selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (4);

[0014]

[0015] In formula (1), Q represents an optionally substituted hydrocarbon group having 4 to 8 carbon atoms which forms a cyclic group together with the sulfur atom of the sulfonyl group, X represents a sulfonyl group or a carbonyl group, and R 1 represents an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom,

[0016]

[0017] In formula (2), Y and Z each independently represent a hydrogen atom or a fluorine atom, a and b each independently represent 0 or 1,

[0018]

[0019] In formula (3), A 1 and A 2 Each independently represents an oxygen atom or a sulfur atom, and R 2 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 1 represents a halogen atom, c represents 1 or 2,

[0020]

[0021] In formula (4), A 3 and A 4 Each independently represents an oxygen atom or a sulfur atom, and R 3 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 2 represents a halogen atom, and d represents 1 or 2.

[0022] [2] The nonaqueous electrolyte solution for a secondary battery according to [1], wherein

[0023] Q is an optionally substituted hydrocarbon group having 4 carbon atoms.

[0024] [3] The nonaqueous electrolyte solution for a secondary battery according to [1] or [2], wherein

[0025] X is a sulfonyl group.

[0026] [4] The nonaqueous electrolyte solution for a secondary battery according to [1] or [2], wherein

[0027] The second compound includes a compound represented by formula (3).

[0028] [5] The non-aqueous electrolyte solution for a secondary battery according to [3], wherein

[0029] The second compound includes a compound represented by formula (3).

[0030] [6] The nonaqueous electrolyte solution for a secondary battery according to [1] or [2], wherein

[0031] The second compound includes a compound represented by formula (2), wherein both Y and Z are fluorine atoms.

[0032] [7] The nonaqueous electrolyte solution for a secondary battery according to any one of [3] to [5], wherein

[0033] The second compound includes a compound represented by formula (2), wherein both Y and Z are fluorine atoms.

[0034] [8] The nonaqueous electrolyte solution for a secondary battery according to any one of [1] to [7], wherein

[0035] The electrolyte includes a lithium salt.

[0036] [9] An additive for addition to a non-aqueous electrolyte in combination with a compound represented by the following formula (1), and comprising at least one selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (4),

[0037]

[0038] In formula (1), Q represents an optionally substituted hydrocarbon group having 4 to 8 carbon atoms which forms a cyclic group together with the sulfur atom of the sulfonyl group, X represents a sulfonyl group or a carbonyl group, and R 1 represents an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom,

[0039]

[0040] In formula (2), Y and Z each independently represent a hydrogen atom or a fluorine atom, a and b each independently represent 0 or 1,

[0041]

[0042] In formula (3), A 1 and A 2 Each independently represents an oxygen atom or a sulfur atom, and R 2 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 1 represents a halogen atom, c represents 1 or 2,

[0043]

[0044] In formula (4), A 3 and A 4 Each independently represents an oxygen atom or a sulfur atom, and R 3 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 2 represents a halogen atom, and d represents 1 or 2.

[0045]

[10] A lithium ion battery comprising the nonaqueous electrolyte solution for a secondary battery according to any one of [1] to [8], a positive electrode, and a negative electrode.

[0046]

[11] A lithium ion capacitor comprising the nonaqueous electrolyte solution for a secondary battery according to any one of [1] to [8], a positive electrode, and a negative electrode.

[0047] Effects of the Invention

[0048] According to the present invention, a nonaqueous electrolyte solution is provided that can improve the high temperature storage characteristics of a secondary battery. Specifically, the nonaqueous electrolyte solution of the present invention can reduce the amount of gas generated when a charged secondary battery is stored at high temperature, and maintain high remaining capacity and recovery capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a cross-sectional view showing an example of a lithium ion battery. DETAILED DESCRIPTION

[0050] The present invention is not limited to the following examples.

[0051] An electrolyte solution for a secondary battery according to one embodiment includes a first compound, a second compound, a nonaqueous solvent, and an electrolyte.

[0052] <First Compound>

[0053] The first compound is a compound represented by the following formula (1).

[0054]

[0055] In formula (1), Q represents an optionally substituted hydrocarbon group having 4 to 8 carbon atoms which forms a cyclic group together with the sulfur atom of the sulfonyl group, X represents a sulfonyl group or a carbonyl group, and R 1 It represents an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom.

[0056] In the present specification, "may be substituted" means that one or more hydrogen atoms possessed by each group may be substituted by a substituent. When the substituent is a halogen atom, "may be substituted by a halogen atom" means that one or more hydrogen atoms possessed by each group may be substituted by a halogen atom.

[0057] As R 1 The alkenyl, alkynyl, alkenyloxy and alkynyloxy groups may be unsubstituted, and may have one or more halogen atoms as substituents. Examples of halogen atoms include iodine atoms, bromine atoms and fluorine atoms. The halogen atom as a substituent may be a fluorine atom. 1 When each group of is substituted by a fluorine atom, the battery resistance can be further reduced.

[0058] The number of carbon atoms of the alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom may be 3 to 5 or 3 to 4. The alkenyl group may be linear or branched. Examples of alkenyl groups having 3 to 6 carbon atoms which may be substituted by a halogen atom include allyl, methallyl, 1-butenyl, 2-butenyl, 3-butenyl, isobutenyl and 1,1-difluoro-1-propenyl. The alkenyl group may be an allyl group which may be substituted by a halogen atom or a methallyl group which may be substituted by a halogen atom. When the alkenyl group is an allyl group which may be substituted by a halogen atom or a methallyl group which may be substituted by a halogen atom, a stronger SEI is easily formed.

[0059] The number of carbon atoms of the alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom may be 3 to 5 or 3 to 4. The alkynyl group may be straight-chain or branched. Examples of alkynyl groups having 3 to 6 carbon atoms which may be substituted by a fluorine atom include 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl and 3-butynyl. The alkynyl group may be a 2-propynyl group which may be substituted by a halogen atom. When the alkynyl group is a 2-propynyl group which may be substituted by a halogen atom, a stronger SEI is easily formed.

[0060] The number of carbon atoms of the alkenyloxy group having 3 to 6 carbon atoms which may be substituted with a halogen atom may be 3 to 5 or 3 to 4. The alkenyloxy group may be linear or branched. Examples of the alkenyloxy group having 3 to 6 carbon atoms which may be substituted with a halogen atom include 2-propenyloxy, 1-methyl-2-propenyloxy, 2-methyl-2-propenyloxy, 2-butenyloxy and 3-butenyloxy.

[0061] The number of carbon atoms in the alkynyloxy group having 3 to 6 carbon atoms which may be substituted with a halogen atom may be 3 to 5 or 3 to 4. The alkynyloxy group may be linear or branched. Examples of the alkynyloxy group having 3 to 6 carbon atoms which may be substituted with a halogen atom include 2-propynyloxy, 1-methyl-2-propynyloxy, 2-methyl-2-propynyloxy, 2-butynyloxy and 3-butynyloxy.

[0062] When X is a sulfonyl group, R 1 It may be an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom; it may be an alkenyl group having 3 to 5 carbon atoms which may be substituted by a halogen atom, or an alkenyloxy group having 3 to 5 carbon atoms which may be substituted by a halogen atom; or it may be an alkenyl group having 3 to 5 carbon atoms which may be substituted by a halogen atom.

[0063] When X is a carbonyl group, R 1 It may be an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom; it may be an alkenyl group having 3 to 5 carbon atoms which may be substituted by a halogen atom, or an alkenyloxy group having 3 to 5 carbon atoms which may be substituted by a halogen atom; or it may be an alkenyl group having 3 to 5 carbon atoms which may be substituted by a halogen atom.

[0064] The hydrocarbon group as Q may be a hydrocarbon group having 4 to 6 carbon atoms or a hydrocarbon group having 4 carbon atoms. In these cases, the battery resistance can be further reduced. The hydrocarbon group as Q may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The number of unsaturated bonds in the unsaturated hydrocarbon group may be 1 or more or 2 or less. The hydrocarbon group as Q may have -OXR in formula (1) at any position. 1 The hydrocarbon group Q may be further substituted with -OXR 1 As a substituent other than the group represented by 1 Examples of substituents that the hydrocarbon group of Q may have other than the groups represented by the above include halogen atoms.

[0065] The compound represented by formula (1) may be a compound represented by the following formula (1a) or the following formula (1b). In this case, the storage characteristics of the secondary battery can be further improved.

[0066]

[0067] In formula (1a), X and R1 Respectively with X and R in formula (1) 1 have the same meaning.

[0068]

[0069] In formula (1b), X and R 1 Respectively with X and R in formula (1) 1 have the same meaning.

[0070] Examples of compounds represented by the above formula (1a) include compounds represented by the following formulas (1-1), (1-3), (1-5), (1-6), (1-7), (1-8) and (1-9). Examples of compounds represented by the above formula (1b) include compounds represented by the following formulas (1-2) and (1-4).

[0071]

[0072] Hereinafter, an example of a synthetic method of a compound represented by the above formula (1-1) is shown. First, 3-hydroxycyclopentane sulfone and allyl sulfonyl chloride are dissolved in an organic solvent and ice-cooled, then, triethylamine is added dropwise and stirred for 1 hour to react. Then, water is added to the reaction solution, the precipitated solid is recovered by filtration, and washed with methanol, so that the target compound can be obtained.

[0073] The content of the first compound can be 0.1% or more, 0.5% or more, or 10% or less, or 5% or less, based on the total mass of the nonaqueous electrolyte. The content of the first compound can be 0.1-10% by mass, 0.1-5% by mass, 0.5-10% by mass, or 0.5-5% by mass, based on the total mass of the nonaqueous electrolyte. In addition, when the nonaqueous electrolyte contains multiple components as the first compound, the content of the first compound represents the total amount of these multiple components.

[0074] <Second compound>

[0075] The second compound is at least one selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (4). The second compound may contain only one of these or two or more of them.

[0076]

[0077] In formula (2), Y and Z each independently represent a hydrogen atom or a fluorine atom, and a and b each independently represent 0 or 1.

[0078]

[0079] In formula (3), A 1 and A 2 Each independently represents an oxygen atom or a sulfur atom, and R 2 represents a direct bond (single bond) or a hydrocarbon group having 1 to 3 carbon atoms, W 1 represents a halogen atom, and c represents 1 or 2.

[0080]

[0081] In formula (4), A 3 and A 4 Each independently represents an oxygen atom or a sulfur atom, and R 3 represents a direct bond (single bond) or a hydrocarbon group having 1 to 3 carbon atoms, W 2 represents a halogen atom, and d represents 1 or 2.

[0082] In formula (2), Y and Z may both be hydrogen atoms, Y and Z may both be fluorine atoms, Y may be a fluorine atom and Z may be a hydrogen atom, or Y may be a hydrogen atom and Z may be a fluorine atom. When both Y and Z are fluorine atoms, the battery resistance can be further reduced.

[0083] Examples of the compound represented by formula (2) include compounds represented by the following formulas (2-1) and (2-2). As the compound represented by formula (2), a commercially available product can be used.

[0084]

[0085] The content of the compound represented by formula (2) can be 0.1% by mass or more or 0.5% by mass or less, or 10% by mass or less or 5% by mass or less, based on the total mass of the nonaqueous electrolyte. The content of the compound represented by formula (2) can be 0.1-10% by mass, 0.1-5% by mass, 0.5-10% by mass or 0.5-5% by mass, based on the total mass of the nonaqueous electrolyte.

[0086] In formula (3), A 1 and A 2 can be all oxygen atoms, A 1 and A 2 They can also all be sulfur atoms, which can be A 1 is an oxygen atom and A 2 A is a sulfur atom or 1 is a sulfur atom and A 2 For oxygen atoms.

[0087] In formula (3), W 1 represents a halogen atom. Examples of halogen atoms include iodine atoms, bromine atoms, and fluorine atoms, and may be fluorine atoms. When c in formula (3) is 1, W1 The number is 4-2c=2, when c is 2, W 1 The number of is 4-2c=0. In formula (3), in W 1 When there are 2, there are 2 W 1 They may be the same or different from each other. In formula (3), there are two W 1 All of them may be fluorine atoms.

[0088] As R 2 The hydrocarbon group of R may be a hydrocarbon group having 1 to 2 carbon atoms or a hydrocarbon group having 1 carbon atom. 2 The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. 2 In the case of a direct bond, the compound represented by the formula (3) becomes a compound represented by the following formula (3a).

[0089]

[0090] A in formula (3a) 1 , A 2 , W 1 and c are respectively the same as A in the above formula (3) 1 , A 2 , W 1 and c have the same meaning.

[0091] Examples of the compound represented by the formula (3) include compounds represented by the following formulas (3-1) and (3-2). As the compound represented by the formula (3), a commercially available product can be used.

[0092]

[0093] The content of the compound represented by formula (3) can be 0.1% by mass or more or 0.5% by mass or more, or 10% by mass or less or 5% by mass or less, based on the total mass of the nonaqueous electrolyte. The content of the compound represented by formula (3) can be 0.1-10% by mass, 0.1-5% by mass, 0.5-10% by mass or 0.5-5% by mass, based on the total mass of the nonaqueous electrolyte.

[0094] In formula (4), A 3 and A 4 can be all oxygen atoms, A 3 and A 4 They can also all be sulfur atoms, which can be A 3 is an oxygen atom and A 4 A is a sulfur atom or 3 is a sulfur atom and A 4 For oxygen atoms.

[0095] In formula (4), W 2 represents a halogen atom. Examples of halogen atoms include iodine atoms, bromine atoms, and fluorine atoms, and may be fluorine atoms. When d in formula (4) is 1, W 2 The number is 6-2d=4, when d is 2, W 2 The number of is 6-2d=2. There are multiple W in formula (4) 2 They may be the same or different. In formula (4), there are multiple W 2 All of them may be fluorine atoms.

[0096] As R 3 The hydrocarbon group of R may be a hydrocarbon group having 1 to 2 carbon atoms or a hydrocarbon group having 1 carbon atom. 3 The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. 3 In the case of a direct bond, the compound represented by formula (4) becomes a compound represented by the following formula (4a).

[0097]

[0098] A in formula (4a) 3 , A 4 , W 2 and d are respectively the same as A in the above formula (4) 3 , A 4 , W 2 and d have the same meaning.

[0099] Examples of the compound represented by the formula (4) include compounds represented by the following formulas (4-1) and (4-2). As the compound represented by the formula (4), a commercially available product can be used.

[0100]

[0101] The content of the compound represented by formula (4) can be 0.1% by mass or more or 0.5% by mass or less, or 10% by mass or less or 5% by mass, based on the total mass of the nonaqueous electrolyte. The content of the compound represented by formula (4) can be 0.1-10% by mass, 0.1-5% by mass, 0.5-10% by mass or 0.5-5% by mass, based on the total mass of the nonaqueous electrolyte.

[0102] The content of the second compound can be 0.1% or more or 0.5% or less, or 10% or less or 5% or less, based on the total mass of the nonaqueous electrolyte. The content of the second compound can be 0.1-10% by mass, 0.1-5% by mass, 0.5-10% by mass or 0.5-5% by mass, based on the total mass of the nonaqueous electrolyte. In addition, when the nonaqueous electrolyte contains multiple components as the second compound, the content of the second compound represents the total amount of these multiple components.

[0103] In the non-aqueous electrolyte, the mass ratio of the content of the second compound to the content of the first compound (content of the second compound / content of the first compound) may be 0.1 or more, 0.25 or more, or 0.5 or more. Furthermore, the mass ratio may be 20 or less, 5 or less, or 3 or less. The mass ratio may be 0.1 to 20, 0.1 to 5, 0.1 to 3, 0.25 to 20, 0.25 to 5, 0.25 to 3, 0.5 to 20, 0.5 to 5, or 0.5 to 3.

[0104] When the second compound is combined with the first compound and added to a non-aqueous electrolyte, the high temperature storage characteristics of the secondary battery can be improved. The additive involved in one embodiment is an additive for adding to a non-aqueous electrolyte in combination with a compound represented by formula (1), and the additive includes at least one selected from the group consisting of a compound represented by formula (2), a compound represented by formula (3), and a compound represented by formula (4).

[0105] <Non-aqueous solvent>

[0106] From the viewpoint of suppressing the viscosity of the secondary battery electrolyte to be relatively low, the nonaqueous solvent may also be an aprotic solvent. The nonaqueous solvent may be at least one selected from the group consisting of cyclic carbonate, linear carbonate, aliphatic carboxylic acid ester, lactone, lactam, cyclic ether, linear ether, sulfone, nitrile and these halogen derivatives. The nonaqueous solvent may include at least one of cyclic carbonate and linear carbonate, or may include a combination of cyclic carbonate and linear carbonate.

[0107] Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, and fluoroethylene carbonate. Examples of chain carbonates include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Examples of aliphatic carboxylic acid esters include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, and methyl trimethylacetate. Examples of lactones include γ-butyrolactone. Examples of lactams include ε-caprolactam and N-methylpyrrolidone. Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, and 1,3-dioxolane. Examples of chain ethers include 1,2-diethoxyethane and ethoxymethoxyethane. Examples of sulfones include sulfolane. Examples of nitrites include acetonitrile. As examples of halogen derivatives, halogen derivatives of cyclic carbonates such as 4-fluoro-1,3-dioxolane-2-one, 4-chloro-1,3-dioxolane-2-one, and 4,5-difluoro-1,3-dioxolane-2-one can be cited. These can be used alone or in combination of two or more. These non-aqueous solvents are particularly suitable for use in secondary batteries such as lithium ion batteries.

[0108] The content of the nonaqueous solvent may be, for example, 70% by mass to 99% by mass based on the total mass of the nonaqueous electrolyte.

[0109] <Electrolytes>

[0110] The electrolyte may include a lithium salt that becomes an ion source of lithium ions or a sodium salt that becomes an ion source of sodium ions. The lithium salt may be at least one selected from the group consisting of LiAlCl4, LiBF4, LiPF6, LiClO4, lithium bistrifluoromethanesulfonyl imide (LiTFSi), lithium bisfluorosulfonyl imide (LiFSi), LiAsF6 and LiSbF6. As a sodium salt, for example, NaPF6, NaBF4, NaClO4, NaAsF6, NaCF3SO3, NaN(CF3SO2)2, NaN(C2F5SO2)2, NaC(CF3SO2)3, etc. can be cited. These can be used alone or in combination of two or more. The electrolyte may include LiBF4 and / or LiPF6. When the electrolyte includes LiBF4 and / or LiPF6, the ionic conductivity of the electrolyte can be improved, and the performance degradation of the secondary battery caused by long-term use can be suppressed by anti-oxidation-reduction properties.

[0111] The concentration of the electrolyte may be 0.1 mol / L or more, or 0.5 mol / L or more, or 2.0 mol / L or less, or 1.5 mol / L or less, based on the total volume of the nonaqueous electrolyte. The concentration of the electrolyte may be 0.1 to 2.0 mol / L, 0.1 to 1.5 mol / L, 0.5 to 2.0 mol / L, or 0.5 to 1.5 mol / L, based on the total volume of the nonaqueous electrolyte.

[0112] <Non-aqueous electrolyte>

[0113] The non-aqueous electrolyte may contain other components as needed. Examples of other components include positive electrode protective agents, flame retardants, overcharge inhibitors, cyclic carbonate compounds, nitrile compounds, isocyanate compounds, compounds having acetylene-1,2-diyl (-C≡C-), compounds having sulfonyl groups other than the above-mentioned first compound, phosphate compounds, acid anhydrides, cyclic phosphazene compounds, compounds containing boron atoms other than the compounds represented by the above formula (3), and compounds containing silicon atoms.

[0114] Examples of cyclic carbonate compounds include 4-fluoro-1,3-dioxolane-2-one (FEC), trans- or cis-4,5-difluoro-1,3-dioxolane-2-one (DFEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), and 4-ethynyl-1,3-dioxolane-2-one (EEC). The cyclic carbonate compound may be VC, FEC, VEC, or a combination thereof.

[0115] Examples of nitrile compounds include mononitrile compounds such as acetonitrile and propionitrile and dinitrile compounds such as succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile and sebaconitrile. The nitrile compound may be succinonitrile, adiponitrile or a combination thereof.

[0116] Examples of the isocyanate compound include methyl isocyanate, ethyl isocyanate, butyl isocyanate, phenyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylene diisocyanate, 2-isocyanate ethyl acrylate, and 2-isocyanate ethyl methacrylate.

[0117] Examples of compounds having an acetylene-1,2-diyl group (-C≡C-) include 2-propynyl methyl carbonate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, 2-propynyl 2-(methylsulfonyloxy)propionate, di(2-propynyl) oxalate, methyl-2-propynyl oxalate, ethyl-2-propynyl oxalate, di(2-propynyl) glutarate, 2-butyne-1,4-diyl dimethanesulfonate, 2-butyne-1,4-diyl dicarboxylate, and 2,4-hexadiyn-1,6-dimethylsulfonate.

[0118] Examples of compounds having a sulfonyl group (>S(=O)2) other than the first compound include 1,3-propane sultone (PS), 1,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-propene sultone, 2,2-dioxy-1,2-oxathiolane-4-acetate and 5,5-dimethyl-1,2-oxathiolane-4-one 2,2-dioxide, vinyl sulfite, vinyl sulfate, hexahydrobenzene Cyclic sulfites such as 1,2-cyclohexanediol cyclic sulfite and 5-vinyl-hexahydro-1,3,2-benzodioxythiol-2-oxide, sulfonate groups such as butane-2,3-dimethylsulfonate, butane-1,4-dimethylsulfonate and methylene disulfonate, 1,3-propanedisulfonic anhydride, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane and bis(2-vinylsulfonylethyl)ether.

[0119] Examples of the phosphate ester compound include trimethyl phosphate, tributyl phosphate, trioctyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) methyl phosphate, bis(2,2,2-trifluoroethyl) ethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2-difluoroethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2,3,3-tetrafluoropropyl phosphate, bis(2,2-difluoroethyl) 2,2,2-trifluoroethyl phosphate, bis(2,2,3,3-tetrafluoropropyl) 2,2,2-trifluoroethyl phosphate, (2,2,2-trifluoroethyl) (2,2,3,3-tetrafluoropropyl) methyl phosphate, tris(1,1,1,3,3,3-hexafluoropropane-2-yl) phosphate, methyl methylenebisphosphonate, and methylenebisphosphonate. 2-(dimethylphosphoryl)acetate, ethyl 2-(dimethylphosphoryl)acetate, methyl 2-(diethylphosphoryl)acetate, ethyl 2-(diethylphosphoryl)acetate, 2-propynyl 2-(dimethylphosphoryl)acetate, 2-propynyl 2-(diethylphosphoryl)acetate, methyl 2-(dimethoxyphosphoryl)acetate, ethyl 2-(dimethoxyphosphoryl)acetate, methyl 2-(diethoxyphosphoryl)acetate, ethyl 2-(diethoxyphosphoryl)acetate, 2-propynyl 2-(dimethoxyphosphoryl)acetate, 2-propynyl 2-(diethoxyphosphoryl)acetate, methyl pyrophosphate and ethyl pyrophosphate.

[0120] Examples of the acid anhydride include acetic anhydride, propionic anhydride, succinic anhydride, maleic anhydride, 3-allylsuccinic anhydride, glutaric anhydride, itaconic anhydride and 3-sulfo-propionic anhydride.

[0121] Examples of the cyclic phosphazene compound include methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0122] Examples of compounds containing a boron atom other than the compound represented by the above formula (3) include boroxine, trimethylboroxine, trimethoxyboroxine, triethylboroxine, triethoxyboroxine, triisopropoxyboroxine, triisopropoxyboroxine, tri-n-propylboroxine, tri-n-propoxyboroxine, tri-n-butylboroxine, tri-n-butoxyboroxine, triphenylboroxine, triphenoxyboroxine, tricyclohexylboroxine and tricyclohexyloxyboroxine.

[0123] Examples of the compound containing a silicon atom include hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, hexaphenylcyclotrisiloxane, 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, trimethylfluorosiloxane, triethylfluorosiloxane, tripropylfluorosiloxane, phenyldimethylfluorosiloxane, triphenylfluorosiloxane, vinyldimethylfluorosiloxane, vinyldiethylfluorosiloxane, vinyldiphenylfluorosiloxane, divinyldifluorosilane, divinyldimethylsilane, trimethoxyfluorosiloxane, triethoxyfluorosiloxane, dimethyldifluorosiloxane, diethyldifluorosiloxane, trivinylfluorosiloxane, trivinylmethylsilane, ethylvinyldifluorosiloxane, methyltrifluorosiloxane, ethyltrifluorosiloxane, hexamethyldisil ... 3-Diethyltetramethyldisiloxane, hexaethyldisiloxane, octamethyltrisiloxane, methoxytrimethylsiloxane, ethoxytrimethylsiloxane, dimethoxydimethylsilane, trimethoxymethylsiloxane, tetramethoxysilane, tetravinylsilane, tetraallylsilane, tetrabutenylsilane, bis(trimethylsilyl)peroxide, trimethylsilyl acetate, triethylsilyl acetate, trimethylsilyl propionate, trimethylsilyl methacrylate, trimethylsilyl trifluoroacetate, trimethylsilyl methanesulfonate, trimethylsilyl ethanesulfonate, triethylsilyl methanesulfonate, trimethylsilyl fluoromethanesulfonate, bis(trimethylsilyl)sulfate, tris(trimethylsilyl)boron, tris(trimethylsilyl)phosphate, and tris(trimethylsilyl)phosphite.

[0124] The non-aqueous electrolyte for secondary batteries described above is particularly useful in the use of secondary batteries. As an example of a secondary battery, it is mainly composed of the above-mentioned non-aqueous electrolyte and a positive electrode and a negative electrode. The secondary battery can be a sodium ion battery or a lithium ion battery, or it can be a lithium ion capacitor. The lithium ion battery involved in one embodiment has the above-mentioned non-aqueous electrolyte for secondary batteries and a positive electrode and a negative electrode. The lithium ion capacitor involved in one embodiment has the above-mentioned non-aqueous electrolyte for secondary batteries and a positive electrode and a negative electrode.

[0125] Figure 1 It is a cross-sectional view schematically showing an example of a lithium ion battery. Figure 1 The lithium ion battery 1 shown in FIG. 1 includes alternately stacked negative electrodes 4 and positive electrodes 9, an electrolyte 5 disposed between the negative electrodes 4 and the positive electrodes 9, and a separator 6 disposed in the electrolyte 5. The plurality of negative electrodes 4 and positive electrodes 9 are stacked so that the main surface of the negative electrode 4 and the main surface of the positive electrode 9 face each other via the separator 6. The lithium ion battery 1 includes 7 layers of negative electrodes 4 and 6 layers of positive electrodes 9. Figure 1In the figure, a part of the repeated structure is omitted. The negative electrode 4 has a negative electrode collector 3 and a negative electrode active material layer 2 provided on both sides of the negative electrode collector 3. The positive electrode 9 has a positive electrode collector 8 and a positive electrode active material layer 7 provided on both sides of the positive electrode collector 8. The non-aqueous electrolyte 5 is the above-mentioned non-aqueous electrolyte for secondary batteries.

[0126] The positive electrode current collector 8 and the negative electrode current collector 3 may be metal foils made of metal such as aluminum, copper, nickel, and stainless steel.

[0127] The positive electrode active material layer 7 contains a positive electrode active material. The positive electrode active material may be a composite oxide containing lithium or a phosphate compound containing lithium. Examples of composite oxides containing lithium include LiMnO2, LiFeO2, LiCoO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2、LiNi 0.5 Co 0.2 Mn 0.3 O2、LiNi 0.6 Co 0.2 Mn 0.2 O2、LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi x Co y M z O2 (wherein 0.01<x<1, 0≤y≤1, 0≤z≤1 and x+y+z=1, M is at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb, Fe, Cu and Al.), Li z Ni (1-x-y) Co x M y O2 (wherein 0≤x≤0.40, 0≤y≤0.40 and 0.90≤z≤1.20, M is at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb and Al.) and Li z Co (1-x) M x O2 (wherein 0≤x≤0.1 and 0.97≤z≤1.20, and M is at least one element selected from the group consisting of Mn, Ni, V, Mg, Mo, Nb and Al.).

[0128] The positive electrode active material may be Li z Ni (1-x-y) Co x M yO2 (wherein 0.01≤x≤0.20, 0≤y≤0.30 and 0.90≤z≤1.20, M is at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb and Al), Li z Ni (1-x-y) Co x M y O2 (wherein 0.01≤x≤0.15, 0≤y≤0.15 and 0.97≤z≤1.20, M is at least one element selected from Mn, V, Mg, Mo, Nb and Al.) or Li z Co (1-x) M x O2 (where 0≤x≤0.1 and 0.97≤z≤1.20, M is at least one element selected from the group consisting of Mn, Ni, V, Mg, Mo, Nb and Al.) In this case, SEI is easily formed on the electrode surface, and as a result, the battery performance can be further improved. z Ni (1-x-y) Co x M y When a positive electrode active material such as O2 (wherein 0.01≤x≤0.20, 0≤y≤0.30 and 0.90≤z≤1.20, M is at least one element selected from Mn, V, Mg, Mo, Nb and Al) has a high Ni content ratio, it tends to easily reduce the capacity of the secondary battery during repeated charge and discharge, but because the above-mentioned non-aqueous electrolyte for secondary batteries contains the first compound and the second compound, it can effectively suppress the reduction in the capacity of the secondary battery.

[0129] The negative electrode active material layer 2 contains a negative electrode active material. The negative electrode active material is, for example, a material that can absorb and release lithium. Examples of negative electrode active materials include carbon materials such as graphite and amorphous carbon, and oxide materials such as indium oxide, silicon oxide, tin oxide, lithium titanate, zinc oxide, and lithium oxide. In addition, the negative electrode active material may be lithium metal or a metal material that can form an alloy with lithium. Examples of metals that can form an alloy with lithium include Cu, Sn, Si, Co, Mn, Fe, Sb, and Ag. The negative electrode active material may include an alloy containing two or three metals including these metals and lithium. These materials may be used alone or in combination of two or more.

[0130] From the viewpoint of high energy density, the negative electrode active material may include a carbon material such as graphite and a Si-based active material selected from Si, Si alloys and Si oxides. From the viewpoint of both cycle characteristics and high energy density, the negative electrode active material may include graphite and Si-based active materials. In these cases, the mass ratio of the Si-based active material to the total mass of the carbon material and the Si-based active material may be 0.5% by mass or more, 1% by mass or more, or 2% by mass or more, or 95% by mass or less, 50% by mass or less or 40% by mass or less. The mass ratio of the Si-based active material to the total mass of the carbon material and the Si-based active material may be 0.5-95% by mass, 0.5-50% by mass, 0.5-40% by mass, 1-95% by mass, 1-50% by mass, 1-40% by mass, 2-95% by mass, 2-50% by mass or 2-40% by mass.

[0131] The positive electrode active material layer 7 and the negative electrode active material layer 2 may further include a binder. As examples of binders, polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber (SBR), carboxymethyl cellulose (CMC), polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide-imide, polyacrylic acid, polyacrylic acid metal salt, polyvinyl alcohol, acrylic acid-polyacrylonitrile, polyacrylamide, polymethacrylic acid and these copolymers can be cited. The positive electrode active material layer and the negative electrode active material layer may include binders that are the same or different from each other. When the positive electrode active material layer includes a binder, the binder included in the positive electrode active material layer may be polyvinylidene fluoride (PVDF). When the negative electrode active material layer includes a binder, the binder included in the negative electrode active material layer may be CMC and / or SBR in particular.

[0132] The positive electrode active material layer 7 and the negative electrode active material layer 2 may further include a conductive aid. As the conductive aid, a substance containing a conductive material such as carbon can be used. Examples of substances containing carbon include carbon fine particles such as carbon, carbon black, acetylene black, and ketjen black, and carbon fibers.

[0133] The separator 6 may be a porous film. The porous film may contain, for example, a resin selected from the group consisting of polyethylene, polypropylene, and fluororesins. The separator 6 may have a single-layer structure or a multi-layer structure consisting of a plurality of layers.

[0134] The specific configurations of the shapes and thicknesses of the components of secondary batteries such as sodium ion batteries, lithium ion batteries, and lithium ion capacitors can be appropriately determined by those skilled in the art. Figure 1 The implementation methods can be changed appropriately.

[0135] Example

[0136] Hereinafter, the present invention will be described in further detail with reference to the following examples, but the present invention is not limited to these examples.

[0137] 1. Preparation of non-aqueous electrolyte for secondary batteries

[0138] In order to prepare the non-aqueous electrolyte, the following components were prepared.

[0139] Compound 1

[0140] (1-1): A compound represented by formula (1-1) synthesized by the following steps

[0141] (1-3): Compound represented by formula (1-3) synthesized by the following steps Other compounds

[0142] (i): A compound represented by the following formula (i)

[0143]

[0144] Compound 2

[0145] (2-2): Compound represented by formula (2-2) (manufactured by Tokyo Chemical Industry Co., Ltd., lithium difluorophosphate)

[0146] (3-1): Compound represented by formula (3-1) (manufactured by Aldrich, lithium difluoro(oxalato)borate)

[0147] (3-2): Compound represented by formula (3-2) (manufactured by Aldrich, lithium bis(oxalato)borate)

[0148] (4-2): Compound represented by formula (4-2) (manufactured by CHEMFISH, lithium difluorobis(oxalato)phosphate)

[0149] <Production Example 1: Synthesis of a compound represented by formula (1-1)>

[0150] 3-Sulfolane (236.3 g, 2.0 mol) and 500 mL of water were added to a 2L four-necked flask equipped with a stirrer, a condenser and a thermometer, and the obtained mixture was heated to 40°C to dissolve 3-sulfolane in water until it became uniform. Sodium hydroxide (104.0 g, 2.6 mol) was added to the obtained solution, and the solution was maintained at 40°C and stirred for 10 hours. Then, the flask was cooled in an ice bath. Concentrated sulfuric acid (130.1 g, 1.3 mol) was added dropwise to the obtained reaction solution for 30 minutes. Solids were precipitated by concentrating and removing a portion of the solvent from the reaction solution. After filtering out the precipitated solids, the obtained filtrate was concentrated to obtain 3-hydroxysulfolane (250.6 g, with a yield of 92% relative to 3-sulfolane).

[0151] Next, in a 200mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 3-hydroxycyclopentane sulfone (5.45g, 40mmol), allyl sulfonyl chloride (6.18g, 44mmol) and acetonitrile 20mL obtained above were added. The flask was cooled in an ice bath, the reaction solution in the flask was stirred, and triethylamine (4.05g, 40mmol) was added dropwise. After the addition was completed, the reaction solution was maintained at 0-5°C and stirred for 1 hour. Then, water was added and the precipitated white solid was filtered out. After washing the obtained solid with methanol, a white solid compound (compound represented by formula (1-1)) (5.28g, the yield relative to 3-hydroxycyclopentane sulfone) was obtained by drying under reduced pressure.

[0152] 1H-NMR (400MHz, CD3CN) δ (ppm): 2.51 (m, 2H), 3.18 (m, 2H), 3.37 (m, 2H), 3.51 (m, 2H) 5.28 (m, 1H), 6.25 (d, 1H), 6.40 (d, 1H), 6.69 (m, 1H)

[0153] <Production Example 2: Synthesis of the compound represented by formula (1-3)>

[0154] In a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, sodium 2-methyl-2-propene-1-sulfonate (8.04 g, 50 mmol), N,N-dimethylformamide (0.37 g, 5 mmol) and 30 mL of dichloromethane were added. The reaction solution in the flask was stirred, and thionyl chloride (7.14 g, 60 mmol) was added dropwise at room temperature (25°C). After the addition was completed, the reaction solution was maintained at 20 to 25°C and stirred for 24 hours. Then, water was added for liquid separation, and the oil layer was concentrated to obtain 2-methyl-2-propene-1-sulfonyl chloride (7.73 g, the yield relative to sodium 2-methyl-2-propene-1-sulfonate was 100%).

[0155] Next, 3-hydroxycyclopentane sulfone (5.45 g, 40 mmol), 2-methyl-2-propylene-1-sulfonyl chloride (6.80 g, 44 mmol) and acetonitrile 20 mL obtained in the first half of the above-mentioned manufacturing example 1 were added to a 200 mL four-necked flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel. The flask was cooled in an ice bath, the reaction solution in the flask was stirred, and triethylamine (4.05 g, 40 mmol) was added dropwise. After the addition was completed, the reaction solution was maintained at 0 to 5° C. and stirred for 1 hour. Then, water was added and the precipitated white solid was filtered out. After washing the obtained solid with methanol, a white solid compound (compound represented by formula (1-3)) (5.84 g, the yield relative to 3-hydroxycyclopentane sulfone) was obtained by drying under reduced pressure.

[0156] 1H-NMR (400MHz, CD3CN) δ (ppm): 1.93 (m, 3H), 2.53 (m, 2H), 3.18 (m, 2H), 3.3 6(dd,1H),3.41(dd,1H),3.97(s,2H),5.15(s,1H),5.22(s,1H),5.42(m,1H)

[0157] <Comparative Example 1>

[0158] A non-aqueous solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume composition ratio of EC:EMC=30:70. A non-aqueous electrolyte for a secondary battery was prepared by dissolving LiPF6 as an electrolyte in the non-aqueous solvent to a concentration of 1 mol / L.

[0159] <Comparative Examples 2 to 7>

[0160] After LiPF6 as an electrolyte was added to a non-aqueous solvent and dissolved, a first compound or a second compound of the type shown in Table 1 was added, and a non-aqueous electrolyte for a secondary battery was prepared in the same manner as in Comparative Example 1. The content of the first compound or the second compound was 1.0% by mass based on the total amount of the non-aqueous electrolyte.

[0161] <Comparative Example 8>

[0162] After adding LiPF6 as an electrolyte to a non-aqueous solvent and dissolving it, a compound represented by formula (i) and a compound represented by formula (4-2) (the second compound) were added, and a non-aqueous electrolyte for a secondary battery was prepared in the same manner as in Comparative Example 1. The content of the compound represented by formula (i) and the compound represented by formula (4-2) was 1.0% by mass, respectively, based on the total amount of the non-aqueous electrolyte.

[0163] <Examples 1 to 6>

[0164] After LiPF6 as an electrolyte was added to a non-aqueous solvent and dissolved, a first compound of the type shown in Table 1 and a second compound of the type shown in Table 1 were added, and a non-aqueous electrolyte for a secondary battery was prepared in the same manner as in Comparative Example 1. The contents of the first compound and the second compound were 1.0% by mass, respectively, based on the total amount of the non-aqueous electrolyte.

[0165] 2. Evaluation

[0166] <Manufacturing of non-aqueous electrolyte secondary batteries>

[0167] A positive electrode sheet (manufactured by Yamaya Co., Ltd.) containing a composite oxide containing lithium and a negative electrode sheet (manufactured by Yamaya Co., Ltd.) containing graphite were prepared. The positive electrode sheet has an aluminum foil (thickness 20 μm) as a positive electrode current collector and a positive electrode active material layer formed on both sides thereof. The positive electrode active material layer contains a composite oxide (LiNi 0.5 Co 0.2 Mn 0.3O2), carbon black (CB) and carbon (KS) as conductive aids, and polyvinylidene fluoride (PVDF) as a binder. Their mass ratio is lithium-containing composite oxide: CB:KS:PVDF=92:2.5:2.5:3. The negative electrode sheet has a copper foil (thickness 10μm) as a negative electrode collector and a negative electrode active material layer formed on both sides thereof. The negative electrode active material layer contains graphite (Gr) as a negative electrode active material and sodium carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) as a binder. Their mass ratio is Gr:CMC:SBR=98:1:1. The negative electrode sheets and the positive electrode sheets are alternately stacked via a separator formed of polypropylene to produce a battery element with a total of 13 layers, including 7 layers of negative electrode sheets and 6 layers of positive electrode sheets as electrodes.

[0168] The battery element prepared by the above method is inserted into a bag formed by a laminated film having an aluminum foil (thickness 40 μm) and a resin layer covering both sides thereof, so that the ends of the positive electrode sheet and the negative electrode sheet protrude from the bag. The non-aqueous electrolyte prepared by each comparative example and each embodiment is further added to the bag, and the bag is vacuum-sealed to obtain a sheet-like non-aqueous electrolyte secondary battery. In order to improve the adhesion between the electrodes, the sheet-like non-aqueous electrolyte secondary battery is pressurized by sandwiching a glass plate.

[0169] <Evaluation of storage characteristics>

[0170] (Determination of initial capacity)

[0171] After each non-aqueous electrolyte secondary battery was charged at 25°C for 1 hour with a current equivalent to 0.1C, it was kept at 25°C for 10 hours. Then, it was charged at a current equivalent to 0.1C for 5 hours and kept at 45°C for 24 hours. Then, at 25°C, after discharging to 3V with a current equivalent to 0.1C, degassing was implemented. Then, the battery was aged by sequentially implementing the following operations to stabilize it: charging to 4.2V with a current equivalent to 0.2C and discharging to 3V with a current equivalent to 0.2C for 3 cycles, charging to 4.2V with a current equivalent to 0.5C and discharging to 3.0V with a current equivalent to 0.5C for 3 cycles, and further charging to 4.2V with a current equivalent to 1C and discharging to 3.0V with a current equivalent to 1C for 3 cycles. Then, as the initial charge and discharge, it was charged and discharged with a current equivalent to 2.0C. The discharge capacity observed during the initial charge and discharge is set to "initial capacity". Then, the volume of the nonaqueous electrolyte secondary battery after the initial capacity was measured was measured by the Archimedean method and was defined as the “initial volume”.

[0172] (Determination of properties after storage)

[0173] At 25°C, the non-aqueous electrolyte secondary battery after initial charge and discharge was charged to 4.2V at 1C and then kept at 60°C for 30 hours. Then, the non-aqueous electrolyte secondary battery was cooled to 25°C and discharged to 3V at a current equivalent to 1C, and the discharge capacity at this time was recorded as the "remaining capacity". In addition, the volume of the battery after the remaining capacity measurement was measured by the Archimedean method and used as the "volume after high-temperature storage". Next, two cycles of charge and discharge were repeated at a current equivalent to 1C, and the discharge capacity of the second cycle was recorded as the "recovery capacity".

[0174] The gas generation amount, remaining capacity maintenance rate, and restored capacity maintenance rate were calculated by the following formulas, respectively.

[0175] Gas generation (cm 3 ) = volume after high temperature storage - initial volume

[0176] Remaining capacity maintenance rate (%) = (remaining capacity / initial capacity) × 100

[0177] Recovery capacity maintenance rate (%) = (recovery capacity / initial capacity) × 100

[0178] The results are shown in Table 1. The amount of gas generated is shown as a relative value when the amount of gas generated in Comparative Example 1 is set to 100.

[0179] [Table 1]

[0180]

[0181] Description of Reference Numerals

[0182] 1-lithium-ion battery, 2-negative electrode active material layer, 3-negative electrode collector, 4-negative electrode, 5-nonaqueous electrolyte, 6-separator, 7-positive electrode active material layer, 8-positive electrode collector, 9-positive electrode.

Claims

1. A non-aqueous electrolyte for a secondary battery, comprising: A first compound represented by the following formula (1); a second compound which is at least one selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (4); Non-aqueous solvents; and Electrolytes, In formula (1), Q represents an optionally substituted hydrocarbon group having 4 to 8 carbon atoms which forms a cyclic group together with the sulfur atom of the sulfonyl group, X represents a sulfonyl group or a carbonyl group, and R 1 represents an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, In formula (2), Y and Z each independently represent a hydrogen atom or a fluorine atom, a and b each independently represent 0 or 1, In formula (3), A 1 and A 2 Each independently represents an oxygen atom or a sulfur atom, and R 2 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 1 represents a halogen atom, c represents 1 or 2, In formula (4), A 3 and A 4 Each independently represents an oxygen atom or a sulfur atom, and R 3 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 2 represents a halogen atom, and d represents 1 or 2.

2. The non-aqueous electrolyte for secondary batteries according to claim 1, wherein The Q is an optionally substituted hydrocarbon group having 4 carbon atoms.

3. The non-aqueous electrolyte for secondary batteries according to claim 1 or 2, wherein The X is a sulfonyl group.

4. The non-aqueous electrolyte for secondary batteries according to claim 1 or 2, wherein The second compound includes a compound represented by the formula (3).

5. The non-aqueous electrolyte for secondary battery according to claim 3, wherein The second compound includes a compound represented by the formula (3).

6. The non-aqueous electrolyte for secondary battery according to claim 1 or 2, wherein The second compound includes a compound represented by the formula (2), The above-mentioned Y and Z are both fluorine atoms.

7. The non-aqueous electrolyte for a secondary battery according to claim 3, wherein The second compound includes a compound represented by the formula (2), The above-mentioned Y and Z are both fluorine atoms.

8. The non-aqueous electrolyte for secondary battery according to claim 1 or 2, wherein The electrolyte includes a lithium salt.

9. An additive for being added to a non-aqueous electrolyte in combination with a compound represented by the following formula (1), and comprising at least one selected from the group consisting of a compound represented by the following formula (2), a compound represented by the following formula (3), and a compound represented by the following formula (4), In formula (1), Q represents an optionally substituted hydrocarbon group having 4 to 8 carbon atoms which forms a cyclic group together with the sulfur atom of the sulfonyl group, X represents a sulfonyl group or a carbonyl group, and R 1 represents an alkenyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkynyl group having 3 to 6 carbon atoms which may be substituted by a halogen atom, an alkenyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, or an alkynyloxy group having 3 to 6 carbon atoms which may be substituted by a halogen atom, In formula (2), Y and Z each independently represent a hydrogen atom or a fluorine atom, a and b each independently represent 0 or 1, In formula (3), A 1 and A 2 Each independently represents an oxygen atom or a sulfur atom, and R 2 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 1 represents a halogen atom, c represents 1 or 2, In formula (4), A 3 and A 4 Each independently represents an oxygen atom or a sulfur atom, and R 3 represents a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, W 2 represents a halogen atom, and d represents 1 or 2. 10 . A lithium ion battery comprising the nonaqueous electrolyte for a secondary battery according to claim 1 or 2 , a positive electrode and a negative electrode. 11 . A lithium ion capacitor comprising the nonaqueous electrolyte for a secondary battery according to claim 1 or 2 , a positive electrode, and a negative electrode.

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