Electrolyte and battery using same

Abstract

The present invention provides a liquid electrolyte that contains a sulfonylimide compound such as LiFSI, high-temperature self-discharging being suppressed in the liquid electrolyte. The present invention is a liquid electrolyte characterized by containing a sulfonylimide compound represented by (1) MN(R1SO2) (R2SO2) (in formula (1), M represents an alkali metal atom, and R1, R2 are the same or different and represent a fluorine atom, C1-6 alkyl groups or C1-6 fluoroalkyl groups), and a compound represented by (2) (in formula (2), R3 represents an optionally substituted hydrocarbon group, M' represents a metal atom, a is an integer of one or greater, b is the number 1 or 2, c, d, e, n are the same or different and each is an integer of 1 or greater, and c×d = n×e).

Description

[Technical Field]

[0001] The present invention relates to an electrolyte solution and a battery using the same, and more particularly to an electrolyte solution constituting a battery such as a lithium ion battery and a battery using the same. [Background technology]

[0002] In recent years, growing concern about environmental issues has led to a shift in energy resources away from fossil fuels such as oil and coal, and this has led to an increase in the importance of batteries, with demand expected to grow accordingly. Secondary batteries, which can be repeatedly charged and discharged, are increasingly being used in a variety of fields, including automobiles and aircraft, as well as in electronic devices such as mobile phones and laptops. Research and development is underway on various secondary batteries and the materials used in them. Lithium-ion batteries, which offer large capacity and are lightweight, are particularly expected to see increased use in the future, and are the subject of the most active research and development.

[0003] For example, with regard to electrodes, a technology has been disclosed that uses a positive electrode active material comprising particles containing a positive electrode material capable of absorbing and releasing an electrode reactant and a coating of a specific metal salt provided on at least a portion of the particles, with the aim of improving battery capacity and charge / discharge cycle characteristics and suppressing gas generation (see Patent Document 1). Furthermore, with regard to electrolytes, a technology has been disclosed that improves battery cycle characteristics by using an electrolyte containing a sulfonylimide compound with a specific structure, such as lithium bisfluorosulfonylimide (LiFSI), and another fluorine-containing alkali metal salt (see Patent Document 2). Another technology has been disclosed that improves ionic conductivity in low-temperature environments by using an electrolyte containing a specific sulfonylimide compound with a specific structure, such as lithium bisfluorosulfonylimide (LiFSI), in a specific ratio, and an electrolyte solution containing a carbonate-based solvent (see Patent Document 3). Furthermore, a nonaqueous electrolyte solution has been disclosed that contains an electrolyte and a compound containing a specific sulfonate anion, and various lithium salts have been disclosed as electrolytes (see Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-193780 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-84591 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-101900 [Patent Document 4] Japanese Patent Publication No. 2022-159173 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, a technology using an imide-based alkali metal salt with a specific structure, such as LiFSI, has been disclosed to improve battery performance. However, an electrolyte containing LiFSI has a problem in that it undergoes large self-discharge when stored at high temperatures.

[0006] The present invention has been made in view of the above-mentioned current situation, and aims to provide an electrolyte solution that contains a sulfonylimide compound such as LiFSI and that suppresses self-discharge at high temperatures. [Means for solving the problem]

[0007] The present inventors have investigated methods for suppressing self-discharge of an electrolyte solution containing a sulfonylimide compound such as LiFSI at high temperatures, and have found that adding a sulfonic acid-based or sulfinic acid-based compound having a hydroxy group of a predetermined structure to an electrolyte solution containing a sulfonylimide compound can suppress self-discharge of the electrolyte solution at high temperatures, thereby arriving at the present invention.

[0008] That is, the present invention is as follows.

[0009] [1] The following formula (1); MN(R 1 SO2)(R 2 SO2) (1) (In formula (1), M represents an alkali metal atom. R 1 , R 2 and are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, and a sulfonylimide compound represented by the following formula (2);

[0010] [ka]

[0011] (In formula (2), R 3 represents a hydrocarbon group which may have a substituent; M' represents a metal atom; a is an integer of 1 or more, and b is the number 1 or 2; c, d, e, and n are the same or different and each is an integer of 1 or more, and c×d=n×e.

[0012] [2] R in the formula (2) 3 The electrolyte solution according to [1], wherein is a hydrocarbon group having 1 to 6 carbon atoms which may have a substituent.

[0013] [3] The electrolytic solution according to [1] or [2], characterized in that the compound represented by the formula (2) is contained in a proportion of 0.0005 to 1.5 mass % relative to 100 mass % of the electrolytic solution.

[0014] [4] The electrolytic solution according to any one of [1] to [3], characterized in that it contains the sulfonylimide compound represented by the formula (1) in a proportion of 0.01 to 5.0 mol / L.

[0015] [5] Furthermore, M 1 PF6, M 1 BF4, M 1 PO2F2, M 1 FSO3(M 1 represents an alkali metal atom.) The electrolytic solution according to any one of [1] to [4], characterized in that it contains at least one of the following.

[0016] [6] The following formula (1); MN(R1 SO2)(R 2 SO2) (1) (In formula (1), M represents an alkali metal atom. R 1 , R 2 and are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, and a sulfonylimide compound represented by the following formula (3);

[0017] [ka]

[0018] (In formula (3), R 4 R represents a hydrocarbon group which may have a substituent, or a divalent group formed by linking multiple hydrocarbon groups which may have a substituent with an oxygen atom or a sulfur atom. 5 represents a hydrogen atom or a hydrocarbon group which may have a substituent. m+ represents a metal cation or an onium cation, and R 4 is an onium cation when it is a hydrocarbon group which may have a substituent; f is an integer of 1 or more, and g is the number 1 or 2; h, i, j, and m are the same or different and each is an integer of 1 or more, and h×i=m×j.

[0019] [7] R in the formula (3) 4 The electrolyte solution according to [6], wherein is a hydrocarbon group having 1 to 6 carbon atoms which may have a substituent.

[0020] [8] The electrolytic solution according to [6] or [7], characterized in that the compound represented by the formula (3) is contained in a proportion of 0.0005 to 1.5 mass % relative to 100 mass % of the electrolytic solution.

[0021] [9] The electrolytic solution according to any one of [6] to [8], characterized in that it contains the sulfonylimide compound represented by the formula (1) in a proportion of 0.01 to 5.0 mol / L.

[0022]

[10] Furthermore, M 1 PF6, M 1 BF4, M 1 PO2F2, M 1 FSO3(M 1 represents an alkali metal atom.) The electrolytic solution according to any one of [6] to [9], characterized in that it contains at least one of the following.

[0023]

[11] A battery comprising the electrolyte solution according to any one of [1] to

[10] .

[0024]

[12] The battery comprises a compound represented by the following formula (5); LiNi x Co y Mn z O2(5) (wherein x, y, and z are numbers satisfying x+y+z=1, 0≦x≦1, 0≦y≦1, and 0≦z≦1) and / or a positive electrode containing LiFePO4.

[0025]

[13] The battery according to

[11] or

[12] , characterized in that the battery is configured with a negative electrode active material containing Si. [Effects of the Invention]

[0026] The electrolyte solution of the present invention is an electrolyte solution that contains a sulfonylimide compound such as LiFSI and yet exhibits suppressed self-discharge at high temperatures, and can be suitably used as an electrolyte solution for batteries intended for use at high temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below. In addition, a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[0028] 1. Electrolyte The electrolyte solution of the present invention is characterized by containing a sulfonylimide compound represented by the above formula (1) and a compound represented by the above formula (2) or a compound represented by the above formula (3). By adding the compound represented by the above formula (2) or the above formula (3), decomposition of the sulfonylimide compound can be suppressed, thereby improving the stability of the electrolyte solution. This makes it possible to suppress self-discharge even when a battery using this electrolyte solution is stored at high temperatures. In addition, it is possible to suppress an increase in resistance during high-temperature cycling. The electrolyte solution of the present invention may contain, in addition to the sulfonylimide compound represented by the formula (1), at least one of the compound represented by the formula (2) or the compound represented by the formula (3), but may also contain both the compound represented by the formula (2) and the compound represented by the formula (3).

[0029] The concentration of the sulfonylimide compound represented by the formula (1) in the electrolytic solution of the present invention is preferably 0.01 to 5.0 mol / L. By including the sulfonylimide compound at such a concentration, the electrolytic solution becomes more excellent in ionic conductivity. The concentration of the sulfonylimide compound is more preferably 0.05 to 2.5 mol / L, and even more preferably 0.1 to 1.5 mol / L. The concentration of the sulfonylimide compound represented by the formula (1) is preferably 0.01 to 5.0 mol / kg, more preferably 0.05 to 2.5 mol / kg, and even more preferably 0.1 to 1.5 mol / kg.

[0030] The content of the compound represented by formula (2) or the compound represented by formula (3) in the electrolytic solution of the present invention is preferably 0.0005 to 1.5 mass% relative to 100 mass% of the total electrolytic solution. By including the compound represented by formula (2) or the compound represented by formula (3) in such a proportion, the ionic conductivity of the electrolytic solution can be improved while more sufficiently suppressing self-discharge of the electrolytic solution. The content of the compound represented by formula (2) or the compound represented by formula (3) is more preferably 0.001 to 1 mass%, even more preferably 0.01 to 0.5 mass%, and particularly preferably 0.05 to 0.3 mass% relative to 100 mass% of the total electrolytic solution. When the electrolytic solution of the present invention contains both the compound represented by the above formula (2) and the compound represented by the above formula (3), the total content ratio thereof is preferably as described above.

[0031] The electrolyte solution of the present invention contains the above-mentioned sulfonylimide compound as an alkali metal salt, but may also contain an alkali metal salt other than the above-mentioned sulfonylimide compound. The concentration of the alkali metal salt other than the sulfonylimide compound in the electrolytic solution of the present invention is not particularly limited, but is preferably 0 to 2.5 mol / L, more preferably 0 to 1.5 mol / L, and even more preferably 0.1 to 1.5 mol / L. The concentration of the alkali metal salt other than the sulfonylimide compound is preferably 0 to 2.5 mol / Kg, more preferably 0 to 1.5 mol / Kg, and even more preferably 0.1 to 1.5 mol / Kg.

[0032] When the electrolytic solution of the present invention contains an alkali metal salt other than the sulfonylimide compound represented by formula (1), the total concentration of the sulfonylimide compound represented by formula (1) and the alkali metal salt is preferably 0.5 to 5 mol / L, more preferably 0.8 to 2.5 mol / L, and even more preferably 1 to 1.5 mol / L. When the electrolytic solution of the present invention contains an alkali metal salt other than the sulfonylimide compound represented by the above formula (1), the total concentration of the sulfonylimide compound represented by the above formula (1) and the alkali metal salt is preferably 0.5 to 5 mol / kg, more preferably 0.8 to 2.5 mol / kg, and even more preferably 1 to 1.5 mol / kg.

[0033] When the electrolytic solution of the present invention contains an alkali metal salt other than the sulfonylimide compound represented by formula (1), the proportion of the sulfonylimide compound represented by formula (1) relative to 100 mol % of the electrolyte in the electrolytic solution (the total of the sulfonylimide compound and other alkali metal salts) is preferably 1 to 99 mol %. This allows the effects of the present invention, which are achieved by including the compound represented by formula (2) or the compound represented by formula (3), to be more fully exhibited. The proportion is more preferably 5 to 90 mol %, even more preferably 10 to 85 mol %, and particularly preferably 10 to 70 mol %.

[0034] The proportion of the solvent contained in the electrolytic solution of the present invention is preferably 50 to 1500 parts by mass, more preferably 150 to 800 parts by mass, and even more preferably 300 to 700 parts by mass, per 100 parts by mass of the electrolyte (the sulfonylimide compound and other alkali metal salts).

[0035] The electrolytic solution of the present invention may contain water at a rate of 1% by mass or less, but the water content is preferably 200 ppm by mass or less. This allows the effects of the present invention to be more fully exhibited. The water content is more preferably 100 ppm by mass or less, and even more preferably 50 ppm by mass or less. The electrolytic solution may not contain substantially any water (it may be about 0 ppm by mass). The water content can be measured using a Karl Fischer water content analyzer.

[0036] The electrolyte solution of the present invention may contain other components other than the sulfonylimide compound represented by the above formula (1), other alkali metal salts, the compound represented by the above formula (2) or the compound represented by the above formula (3), and the solvent. The content of other components is not particularly limited, but is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to 100% by mass of the electrolyte solution.

[0037] The essential components and optional components contained in the electrolyte solution of the present invention will be further described below. <Sulfonylimide compounds> The electrolyte solution of the present invention comprises a compound represented by the following formula (1): MN(R 1 SO2)(R 2 SO2) (1) (In formula (1), M represents an alkali metal atom. R 1 , R 2 are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms.

[0038] In the above formula (1), examples of the alkali metal represented by M include lithium, sodium, potassium, rubidium, etc. Preferred are lithium, sodium, and potassium, and more preferred is lithium.

[0039] Above R 1 , R 2Examples of the alkyl group having 1 to 6 carbon atoms in the formula (I) include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl (amyl), and n-hexyl; branched alkyl groups such as i-propyl, sec-butyl, i-butyl, t-butyl, 1-methylbutyl, 1-ethylpropyl, 2-methylbutyl, i-amyl, neopentyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, t-amyl, 1,3-dimethylbutyl, 3,3-dimethylbutyl, and 2-ethylbutyl; and cyclic alkyl groups such as cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclobutylmethyl, cyclopentyl, and cyclohexyl. Of these, linear alkyl groups are preferred.

[0040] Above R 1 , R 2 The alkyl group preferably has 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably 1 to 2 carbon atoms.

[0041] Above R 1 , R 2 The fluoroalkyl group having 1 to 6 carbon atoms may be an alkyl group having 1 to 6 carbon atoms in which at least some of the hydrogen atoms bonded to carbon atoms have been substituted with fluorine atoms. Specific examples of the alkyl group are as described above. Examples of the fluoroalkyl group having 1 to 6 carbon atoms include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, a pentafluoroethyl group, a fluoropropyl group, a fluoropentyl group, and a fluorohexyl group.

[0042] Above R 1 , R 2 The fluoroalkyl group preferably has 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably 1 to 2 carbon atoms.

[0043] Examples of the sulfonylimide compound include lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, lithium (fluorosulfonyl)(pentafluoroethylsulfonyl)imide, potassium bis(fluorosulfonyl)imide, potassium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, sodium bis(fluorosulfonyl)imide, and sodium (fluorosulfonyl)(trifluoromethylsulfonyl)imide. Among these, lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, and lithium (fluorosulfonyl)(pentafluoroethylsulfonyl)imide are preferred, and lithium bis(fluorosulfonyl)imide (LiFSI) is more preferred.

[0044] <Compound represented by the above formula (2)> The following formula (2):

[0045] [ka]

[0046] (In formula (2), R 3 represents a hydrocarbon group which may have a substituent. M' represents a metal atom. a is an integer of 1 or more, and b is the number 1 or 2. c, d, e, and n are the same or different and each is an integer of 1 or more, and c×d=n×e. An electrolyte solution containing a compound represented by

[0047] In the above formula (2), R 3 represents a divalent hydrocarbon group which may have a substituent. The hydrocarbon group may have a linear or branched chain structure, a cyclic structure, or both a chain structure and a cyclic structure. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The number of carbon atoms in the hydrocarbon group is not particularly limited, but in the case of a chain structure, it is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 2. When the hydrocarbon group has a cyclic structure or both a chain structure and a cyclic structure, the hydrocarbon group preferably has 3 to 12 carbon atoms, more preferably 3 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms.

[0048] R in the above formula (2) 3 The substituents which may be possessed by the alkyl group are not particularly limited, and examples thereof include a carboxyl group, a sulfonic acid group, a phosphonic acid group, phosphoric acid, and esters and salts thereof; an amino group, a hydroxyl group, a ketone group, a sulfonic acid group, a thiol group, and a halogen group.

[0049] In the above formula (2), M' represents a metal atom, n+ represents a metal cation. The type of metal element M' is not particularly limited, but is preferably any of Group 1 elements of the periodic table such as lithium, sodium, potassium, rubidium, etc.; and Group 2 elements of the periodic table such as beryllium, magnesium, calcium, strontium, etc. More preferably, it is a Group 1 element of the periodic table, and even more preferably, it is lithium.

[0050] In the above formula (2), a may be any integer of 1 or greater, and is preferably an integer of 1 to 12. An integer of 1 to 6 is more preferred, and an integer of 1 to 4 is even more preferred. In the above formula (2), c, d, e, and n are the same or different and each is an integer of 1 or more, and c is preferably an integer of 1 to 4. More preferably, it is 1 or 2. d is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0051] <Compound represented by the above formula (3)> The following formula (3):

[0052] [ka]

[0053] (In formula (3), R 4 R represents a hydrocarbon group which may have a substituent, or a divalent group formed by linking multiple hydrocarbon groups which may have a substituent with an oxygen atom or a sulfur atom. 5 represents a hydrogen atom or a hydrocarbon group which may have a substituent. m+ represents a metal cation or an onium cation, and R 4 is an optionally substituted hydrocarbon group, it represents an onium cation. f is an integer of 1 or more, and g is the number 1 or 2. h, i, j, and m are the same or different and each is an integer of 1 or more, where h×i=m×j. An electrolyte solution containing a compound represented by the formula (I) is one embodiment of the electrolyte solution of the present invention.

[0054] In the above formula (3), R 4 R represents a divalent hydrocarbon group which may have a substituent, or a divalent group formed by linking multiple hydrocarbon groups which may have a substituent with an oxygen atom or a sulfur atom. 4 When R is a divalent hydrocarbon group which may have a substituent, 4 is R in the above formula (2). 3 The same can be mentioned. R 4 is a divalent group formed by linking a plurality of hydrocarbon groups which may have a substituent with an oxygen atom or a sulfur atom, the divalent group is represented by the following formula (4):

[0055] [ka]

[0056] (In formula (4), R 6 , R 7 are the same or different and represent a hydrocarbon group which may have a substituent. X are the same or different and represent an oxygen atom or a sulfur atom. r represents a number from 1 to 12. In the above formula (4), r may be a number from 1 to 12, but is preferably 1 to 6. It is more preferably 1 to 4, and even more preferably 1 to 2. In the above formula (4), X may be either an oxygen atom or a sulfur atom, and when there are multiple Xs, they may contain both oxygen atoms and sulfur atoms.

[0057] In the above formula (4), R 6 , R 7 The hydrocarbon group in may be of a linear or branched chain structure, a cyclic structure, or a structure having both a chain structure and a cyclic structure. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The number of carbon atoms in the hydrocarbon group is not particularly limited, but in the case of a chain structure, it is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 2. When the hydrocarbon group has a cyclic structure or both a chain structure and a cyclic structure, the hydrocarbon group preferably has 3 to 12 carbon atoms, more preferably 3 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms.

[0058] R in the above formula (3) 5 represents a hydrogen atom or a hydrocarbon group which may have a substituent. The hydrocarbon group may have a linear or branched chain structure, a cyclic structure, or both a chain structure and a cyclic structure. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The number of carbon atoms in the hydrocarbon group is not particularly limited, but in the case of a chain structure, it is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 2. When the hydrocarbon group has a cyclic structure or both a chain structure and a cyclic structure, the hydrocarbon group preferably has 3 to 12 carbon atoms, more preferably 3 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms.

[0059] In the above formulas (3) and (4), R 5 , R 6 , and R 7 The substituent that the hydrocarbon group in R in the above formula (2) may have is not particularly limited. 3 The substituents may be the same as those that the hydrocarbon group may have.

[0060] In the above formula (3), M'' m+ When M is a metal cation, specific examples and preferred examples are M' in the above formula (2). n+ is the same as: In the above formula (3), M'' m+ When is an onium cation, examples of the onium cation include ammonium cation, phosphonium cation, oxonium cation, sulfonium cation, fluoronium cation, and chloronium cation, and any of these may be used, but ammonium cation and phosphonium cation are preferred.

[0061] In the above formula (3), the preferred ranges of f, h, i, j, and m are the same as those of a, c, d, e, and n in the above formula (2), respectively.

[0062] The electrolyte solution of the present invention may contain other components as long as it contains the sulfonylimide compound represented by the above formula (1) and the compound represented by the above formula (2) or the compound represented by the above formula (3). Examples of other components include electrolytes other than the sulfonylimide compound represented by the above formula (1), and additives other than the compound represented by the above formula (2) and the compound represented by the above formula (3).

[0063] <Other alkali metal salts> When the electrolytic solution of the present invention contains an alkali metal salt other than the sulfonylimide compound represented by the above formula (1), the other alkali metal salt is not particularly limited as long as it is an alkali metal salt other than the above sulfonylimide compound, and examples thereof include alkali metal salts of fluorophosphates such as LiPF6 and LiPO2F2; alkali metal salts of fluorosulfonic acids such as LiFSO3; alkali metal salts of trifluoromethanesulfonic acids such as LiCF3SO3; imide-based alkali metal salts such as LiN(CF3SO2)2; alkali metal salts of perfluoroalkanesulfonylmethides such as LiC(CF3SO2)3; LiPF α (C β F 2β+1 ) 6-α Fluorophosphates such as (0≦α≦6, 1≦β≦2); alkali metal perchlorates such as LiClO4; LiBF γ (C δ F 2δ+1 ) 4-γ (0≦γ≦4, 1≦δ≦2); alkali metal salts of oxalatoborates such as LiBOB; cyanoborates such as lithium tetracyanoborate; and alkali metal salts such as LiAsF6, LiI, and LiSbF6, and one or more of these can be used.

[0064] The other alkali metal salts are preferably M 1 PF6, M 1 BF4, M 1 PO2F2, M 1 FSO3(M 1 represents an alkali metal atom.) and M 1 PF6, M 1 BF4, M 1 PO2F2, M 1 FSO3(M 1 represents an alkali metal atom.) is one of the preferred embodiments of the electrolyte solution of the present invention. M 1 PF6, M 1 BF4, M 1 PO2F2, M 1 M in FSO3 1Specific examples and preferred forms of the alkali metal atom are the same as those of the alkali metal atom in the sulfonylimide compound.

[0065] <Solvent> The solvent contained in the electrolytic solution of the present invention is non-aqueous and is not particularly limited as long as it can dissolve the above electrolyte (sulfonylimide compound and other alkali metal salts), the compound represented by the above formula (2), the compound represented by the above formula (3), and other components described later. Examples of suitable solvents include: chain carbonates such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and chloroethylene carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane; Examples of suitable non-aqueous solvents include ethers, lactones such as γ-butyrolactone, γ-valerolactone, and α-methyl-γ-butyrolactone, chain carboxylic acid esters such as ethyl acetate, methyl propionate, and methyl butyrate, fluorinated cyclic carbonates such as fluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4-difluoroethylene carbonate, tetrafluoroethylene carbonate, and 4-fluoro-5-methylethylene carbonate, fluorinated chain carbonates such as trifluorodimethyl carbonate, trifluorodiethyl carbonate, and trifluoroethylmethyl carbonate, and chain nitriles such as acetonitrile, propionitrile, succinonitrile, and adiponitrile. These non-aqueous solvents may be used alone or in combination of two or more. Among these, preferred are chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and 4,5-difluoroethylene carbonate; and chain carboxylic acid esters such as ethyl acetate, methyl propionate, and methyl butyrate.

[0066] The content of the solvent is not particularly limited and can be any as long as it does not significantly impair the effects of the present invention, but when cyclic carbonates are used among the solvents, the content is preferably 5% by volume or more, more preferably 10% by volume or more, based on the total amount of non-aqueous solvents in the non-aqueous electrolyte solution.Furthermore, the content of the cyclic carbonates is preferably 50% by volume or less, more preferably 40% by volume or less, even more preferably 30% by volume or less, and particularly preferably 25% by volume or less, based on the total amount of non-aqueous solvents in the non-aqueous electrolyte solution. The content of the cyclic carbonates is preferably 5 to 50% by volume, more preferably 5 to 40% by volume, even more preferably 10 to 30% by volume, and particularly preferably 10 to 25% by volume, relative to the total amount of the nonaqueous solvent in the nonaqueous electrolyte solution.

[0067] Furthermore, when chain carboxylic acid esters and chain carbonates are used among the above solvents, their contents are not particularly limited, but are preferably 50% by volume or more, more preferably 60% by volume or more, even more preferably 70% by volume or more, and particularly preferably 75% by volume or more, based on the total amount of nonaqueous solvent in the nonaqueous electrolyte solution. Furthermore, the contents of chain carboxylic acid esters and chain carbonates are preferably 95% by volume or less, more preferably 90% by volume or less, based on the total amount of nonaqueous solvent in the nonaqueous electrolyte solution. The range of the content of the chain carboxylic acid esters and chain carbonates relative to the total amount of the nonaqueous solvent in the nonaqueous electrolyte solution is preferably 50 to 95% by volume, more preferably 60 to 95% by volume, even more preferably 70 to 90% by volume, and still more preferably 75 to 90% by volume.

[0068] When a cyclic carbonate and a chain carboxylic acid ester and / or a chain carbonate are used in combination as a solvent, the volume ratio of the cyclic carbonate to the chain carboxylic acid ester and / or a chain carbonate ((cyclic carbonate) / (chain carboxylic acid ester and / or a chain carbonate)) is preferably 5 / 95 to 50 / 50, more preferably 5 / 95 to 40 / 60, even more preferably 10 / 90 to 30 / 70, and particularly preferably 10 / 90 to 25 / 75.

[0069] <Other ingredients> In the electrolytic solution of the present invention, other components besides the sulfonylimide compound represented by the above formula (1), other alkali metal salts, the compound represented by the above formula (2), the compound represented by the above formula (3), and the solvent include, for example, carbonate compounds such as vinylene carbonate, methylvinylene carbonate, ethylvinylene carbonate, 2-vinylethylene carbonate, phenylethylene carbonate, and erythrityl carbonate; 1,3-propane sultone, 1,4-butane sultone, 1,5-pentane sultone, and 1,4-hexane sultone. sulfonic acid esters such as sultone, 4,6-heptanesultone, methyl methanesulfonate, methyl benzenesulfonate, and methyl trifluoromethanesulfonate; sulfone compounds such as sulfolane, 3-methylsulfolane, ethyl methyl sulfone, diphenyl sulfone, and bis(4-fluorophenyl) sulfone; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, and cyclopentanetetracarboxylic dianhydride; Carboxylic acid anhydrides such as phenylsuccinic anhydride; nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide; sulfamic acid (amidosulfuric acid, H3NSO3); sulfamic acid salts (alkali metal salts such as lithium salt, sodium salt, and potassium salt; alkaline earth metal salts such as calcium salt, strontium salt, and barium salt); other gold salts such as manganese salt, copper salt, zinc salt, iron salt, cobalt salt, and nickel salt. metal salts; ammonium salts; guanidine salts, etc.); phosphates such as monofluorophosphates and difluorophosphates; fluorosulfonic acid compounds such as lithium fluorosulfonate (LiFSO3), sodium fluorosulfonate (NaFSO3), potassium fluorosulfonate (KFSO3), and magnesium fluorosulfonate (Mg(FSO3)2); hydrocarbon compounds such as heptane, octane, cycloheptane, cyclohexylbenzene, and amylbenzene; and the like, and one or more of these can be used.

[0070] 2.Battery The present invention also relates to a battery comprising the electrolyte solution of the present invention. The electrolyte solution of the present invention is an electrolyte solution that contains the sulfonylimide compound represented by the above formula (1) and that effectively suppresses self-discharge when stored at high temperatures, and a battery constructed using this electrolyte solution also becomes a battery that effectively suppresses self-discharge when stored at high temperatures.

[0071] The shape of the battery of the present invention is not particularly limited, and any of the conventionally known shapes of batteries can be used, such as cylindrical, prismatic, laminated, coin, large, etc. Furthermore, when used as a high-voltage power source (several tens of volts to several hundreds of volts) to be mounted on electric vehicles, hybrid electric vehicles, etc., the battery can also be made into a battery module constructed by connecting individual batteries in series.

[0072] The battery of the present invention is preferably an alkali metal battery, more preferably a secondary battery, and in one preferred embodiment of the present invention, the battery is a lithium ion secondary battery. The positive electrode, negative electrode, and separator that constitute the battery of the present invention will be described below.

[0073] The positive electrode constituting the battery is not particularly limited, but is a positive electrode active material composition containing a positive electrode active material, a conductive additive, a binder, a dispersion solvent, etc., supported on a positive electrode current collector, and is usually formed into a sheet shape.

[0074] Examples of methods for producing a positive electrode include a method in which a positive electrode active material composition is applied to a positive electrode current collector by a doctor blade method or the like, or the positive electrode current collector is immersed in a positive electrode active material composition and then dried; a method in which a sheet obtained by kneading and molding a positive electrode active material composition and drying it is bonded to a positive electrode current collector via a conductive adhesive, followed by pressing and drying; and a method in which a positive electrode active material composition to which a liquid lubricant has been added is applied or cast onto a positive electrode current collector, molded into a desired shape, the liquid lubricant is removed, and then the composition is stretched in uniaxial or multiaxial directions.

[0075] The material of the positive electrode current collector is not particularly limited, and for example, conductive metals such as aluminum, aluminum alloy, SUS (stainless steel), and titanium can be used. Among them, aluminum is preferred from the viewpoints of being easy to process into a thin film and being inexpensive.

[0076] As the positive electrode active material, it is only necessary that it can occlude and release ions, and conventionally known positive electrode active materials are used. Specifically, M 2 CoO2, M 2 NiO2, M 2 MnO2, M 2 Ni x Co y Mn z O2 and M 2 Ni x Co y Al z O2 (x, y, z are numbers satisfying x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), composite metal oxides such as ternary system oxides, M 2 p Ni q Mn (2-q) O4 (0.9 ≦ p ≦ 1.1, 0 < q < 1), nickel manganate, M 3 APO4 (A = Fe, Mn, Ni, Co) and other compounds having an olivine structure, solid solution materials incorporating a plurality of transition metals (electrochemically inert layered M 2 2MnO3 and electrochemically active layered M 2 M 4 O ([M 4 = transition metals such as Co, Ni] solid solution) (M 2 represents an alkali metal ion), etc. can be exemplified as the positive electrode active material. These positive electrode active materials may be used alone or in combination of a plurality. Among these, as the positive electrode active material, the following formula (5); LiNi x Co y Mn z O2(5) (In formula (5), x, y, and z are numbers that satisfy x+y+z=1, 0≦x≦1, 0≦y≦1, and 0≦z≦1.) A battery comprising a positive electrode containing such a positive electrode active material is one of the preferred embodiments of the present invention.

[0077] Examples of the conductive additive include acetylene black, carbon black, graphite, metal powder materials, single-walled carbon nanotubes, multi-walled carbon nanotubes, vapor-grown carbon fibers, and the like, and one or more of these can be used.

[0078] Examples of binders include fluorine-based resins such as polyvinylidene fluoride and polytetrafluoroethylene; synthetic rubbers such as styrene-butadiene rubber and nitrile-butadiene rubber; polyamide-based resins such as polyamideimide; polyolefin-based resins such as polyethylene and polypropylene; poly(meth)acrylic resins; polyacrylic acid; cellulose-based resins such as carboxymethyl cellulose; and the like, and one or more of these can be used. These binders may be dissolved in a solvent or dispersed in a solvent when used.

[0079] The amounts of the conductive additive and binder to be blended can be adjusted as appropriate in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.), ion conductivity, and the like.

[0080] When producing a positive electrode, examples of solvents used in the positive electrode active material composition include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, tetrahydrofuran, acetonitrile, acetone, ethanol, ethyl acetate, and water. These solvents may be used in combination. The amount of solvent used is not particularly limited and may be determined appropriately depending on the production method and materials used.

[0081] The negative electrode constituting the battery is not particularly limited, but is a negative electrode active material composition containing a negative electrode active material, a dispersion solvent, a binder, and, if necessary, a conductive additive, etc., supported on a negative electrode current collector, and is usually formed into a sheet shape.

[0082] The material of the negative electrode current collector can be a conductive metal such as copper, iron, nickel, silver, stainless steel (SUS), etc. Copper is preferred from the viewpoint of ease of processing into a thin film.

[0083] The negative electrode active material may be any conventionally known negative electrode active material used in batteries, as long as it is capable of absorbing and releasing ions. Specifically, examples of the negative electrode active material include alkali metals, metal alloys such as alkali metal-aluminum alloys, graphite materials such as artificial graphite and natural graphite, mesophase sintered bodies made from coal and petroleum pitch, carbon materials such as non-graphitizable carbon, Si-based negative electrode materials such as Si, Si alloys, and SiO, and Sn-based negative electrode materials such as Sn alloys. Among these, a Si-based negative electrode material containing Si is preferred as the negative electrode active material. A battery comprising a negative electrode containing such a negative electrode active material is one of the preferred embodiments of the present invention.

[0084] The negative electrode can be manufactured by the same method as the positive electrode, and the conductive additive, binder, and material dispersion solvent used in manufacturing the negative electrode are also the same as those used in manufacturing the positive electrode.

[0085] The separator is disposed to separate the positive electrode from the negative electrode. The separator constituting the battery is not particularly limited, and any separator that is commonly used can be used. Examples of the separator include a porous sheet made of a polymer capable of absorbing and retaining a non-aqueous electrolyte solution (e.g., a polyolefin-based microporous separator or a cellulose-based separator), a nonwoven fabric separator, a porous metal body, etc. Among these, a polyolefin-based microporous separator is preferred because it is chemically stable against organic solvents.

[0086] Examples of the material for the porous sheet include polyethylene, polypropylene, and a laminate having a three-layer structure of polypropylene / polyethylene / polypropylene.

[0087] Examples of materials for the nonwoven fabric separator include cotton, rayon, acetate, nylon, polyester, polypropylene, polyethylene, polyimide, aramid, and glass. Depending on the mechanical strength required of the nonaqueous electrolyte layer, the above-exemplified materials can be used alone or in combination. [Example]

[0088] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by weight" and "%" means "% by mass."

[0089] Synthesis Example 1: Synthesis of lithium 2-(2-hydroxyethoxy)ethanesulfonate A 100ml flask was charged with 3.2g of lithium sulfite n-hydrate, 10mL of ion-exchanged water, and 3.3g of ethylene glycol mono-2-chloroethyl ether, and the mixture was heated under reflux for 22 hours. After the volatiles were removed under reduced pressure, 10ml of ethanol was added, and the insoluble matter was removed by filtration. The ethanol in the filtrate was removed under reduced pressure, and the precipitated solid was washed with a large amount of acetone and dried to obtain 1.9g of the desired compound.

[0090] Synthesis Example 2: Synthesis of tetrabutylphosphonium hydroxyethanesulfonate 5.0 g of 40% tetrabutylphosphonium hydroxide was added dropwise to 1.3 g of a 70% aqueous solution of hydroxyethanesulfonic acid at 0°C, and the mixture was stirred for 1 hour. After that, water was removed using an evaporator, and the residue was dehydrated by vacuum drying at 70°C, yielding 2.78 g of the target product.

[0091] Synthesis Example 3: Synthesis of tetraethylphosphonium hydroxyethanesulfonate 10.8 g of 8% tetraethylphosphonium hydroxide was added dropwise to 0.88 g of a 70% aqueous solution of hydroxyethanesulfonic acid at 0°C, and the mixture was stirred for 1 hour. After that, water was removed using an evaporator, and the residue was dehydrated by vacuum drying at 70°C, yielding 1.28 g of the target product.

[0092] Synthesis Example 4: Synthesis of tetramethylammonium hydroxyethanesulfonate 3.7 g of 25% tetramethylammonium hydroxide was added dropwise to 1.8 g of a 70% aqueous solution of hydroxyethanesulfonic acid at 0°C, and the mixture was stirred for 1 hour. After that, water was removed using an evaporator, and the residue was dehydrated by vacuum drying at 60°C, yielding 1.98 g of the target product.

[0093] Synthesis Example 5: Synthesis of lithium 2-methoxyethanesulfonate

[0094] [ka]

[0095] 8.05g (85.1mmol) of 2-chloroethyl methyl ether, 11.82g (75mmol as 60% ethanol), and 20g of ion-exchanged water were added and heated under reflux for 20 hours. After heating under vacuum at 60°C overnight, the water was distilled off under reduced pressure. After drying under vacuum at 60°C, the residue was dissolved in methanol, the insoluble matter was removed by filtration, and the methanol was removed under reduced pressure. Acetone was added to the resulting viscous substance, and the acetone-soluble matter was extracted. The acetone was then evaporated to dryness to obtain the target compound.

[0096] Synthesis Example 6: Synthesis of sodium 2-methoxyethanesulfonate The synthesis of lithium 2-methoxyethanesulfonate was carried out in the same manner as in Synthesis Example 5, except that 10.02 g (79.5 mmol) of sodium sulfite was used instead of lithium sulfite n-hydrate.

[0097] Synthesis Example 7: Synthesis of tetrabutylphosphonium 2-methoxyethanesulfonate An aqueous solution of sodium 2-methoxyethanesulfonate (1.0 g) was mixed with 2 ml of hydrochloric acid and stirred for 2 hours. The mixture was diluted with isopropyl alcohol, and insoluble matter was filtered off. The filtrate was concentrated under reduced pressure to obtain 2-methoxyethanesulfonic acid. This 2-methoxyethanesulfonic acid was diluted with water, and 40% aqueous tetrabutylphosphonium hydroxide solution was added dropwise at 0°C until the pH reached 7, followed by stirring for 1 hour. Water was removed using an evaporator, and the mixture was dehydrated by vacuum drying at 60°C to obtain the target product.

[0098] Synthesis Example 8: Synthesis of tetramethylammonium 2-methoxyethanesulfonate The synthesis of tetrabutylphosphonium 2-methoxyethanesulfonate was carried out in the same manner as in Synthesis Example 7, except that 8% tetramethylammonium hydroxide was used instead of the 40% aqueous solution of tetrabutylphosphonium hydroxide.

[0099] Examples 1-1 to 1-15, Comparative Example 1-1 An electrolyte solution was prepared by dissolving LiFSI (manufactured by Nippon Shokubai Co., Ltd.) in dimethyl carbonate (DMC) to a concentration of 2.9 mol / L (3.56 mol / Kg). 0.1 wt% of each of the compounds listed in Table 1 was added to this electrolyte solution to prepare the electrolyte solution. The electrolyte solution was analyzed by anion ion chromatography immediately after preparation (initial), after one month of storage at 40°C, and after three months of storage at 40°C. - , SO4 - The ions were calibrated and the results are shown in Table 1.

[0100] Examples 1-16 to 1-21 An electrolyte solution was prepared by dissolving LiFSI (manufactured by Nippon Shokubai Co., Ltd.) in dimethyl carbonate (DMC) to a concentration of 2.9 mol / L (3.56 mol / Kg). 0.5 wt% of each of the compounds listed in Table 1 was added to this electrolyte solution to prepare the electrolyte solution. The electrolyte solution was analyzed by anion ion chromatography immediately after preparation (initial), after one month of storage at 40°C, and after three months of storage at 40°C. - , SO4 - The ions were calibrated and the results are shown in Table 1.

[0101] [Table 1]

[0102] Examples 2-1 to 2-15, Comparative Example 2-1 Commercially available LiPF6 and LiFSI (manufactured by Nippon Shokubai Co., Ltd.) were dissolved in a commercially available mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC / EMC = 3 / 7 (vol / vol)) to a concentration of 0.6 mol / L (0.59 mol / Kg), and 0.1 wt% of each of the compounds listed in Table 2 was added to prepare an electrolyte solution. The electrolyte solution was analyzed by anion ion chromatography immediately after preparation (initial), after one month of storage at 40°C, and after three months of storage at 40°C. - , SO4 - The ions were calibrated and the results are shown in Table 2.

[0103] Examples 2-16 to 2-21 Commercially available LiPF6 and LiFSI (manufactured by Nippon Shokubai Co., Ltd.) were dissolved in a commercially available mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC / EMC = 3 / 7 (vol / vol)) to a concentration of 0.6 mol / L (0.59 mol / Kg), and 0.5 wt% of each of the compounds listed in Table 2 was added to prepare an electrolyte solution. The electrolyte solution was analyzed by anion ion chromatography immediately after preparation (initial), after one month of storage at 40°C, and after three months of storage at 40°C. - , SO4 - The ions were calibrated and the results are shown in Table 2.

[0104] [Table 2]

[0105] Examples 3-1 to 3-50, Comparative Example 3-1 (1) Laminated battery fabrication Ternary positive electrode (LiNi1 / 3 Co 1 / 3 Mn 1 / 3 O2 (Umicore), acetylene black (Denka Black), graphite (SP270), and polyvinylidene fluoride (PVdF, #1120) were weighed in a mass ratio of 100:3:3:3 and dispersed in NMP to create a slurry. The slurry was coated on one side of aluminum foil, dried, and roll-pressed to create a positive electrode. An aqueous slurry with a composition (mass ratio) of graphite (SMG / SFG15 = 85 / 15):carbon fiber (VGCF):styrene butadiene rubber (SBR):carboxymethyl cellulose (CMC) = 100:2:1.5:1.5 was prepared, and this was coated on one side of copper foil, dried, and roll-pressed to form a negative electrode. The obtained positive and negative electrodes were cut, polarity leads were ultrasonically welded, and the electrodes were placed opposite each other with a 20 μm polyethylene (PE) separator, and the three sides were sealed with a laminate exterior. 700 μL of the electrolyte solution of the example or comparative example was added to one of the unsealed sides. The electrolyte was prepared by dissolving LiFSI and LiPF6 in a mixed solvent of EC / EMC = 3 / 7 (vol / vol) so that each was 0.6 mol / L (0.59 mol / Kg), and adding the compounds shown in Tables 3 and 4 in the proportions shown in Tables 3 and 4. After the electrolyte was injected, the battery was pre-charged at 0.2C (6mA) for two hours while unpacked. It was then vacuum sealed and left at room temperature for three days. After three days, it was charged at 0.5C (15mA) for five hours to 4.2V, then charged and discharged at 0.2C (6mA) with a termination at 2.75V. One piece of the laminate was then opened and vacuum sealed again to release the gas. After degassing, the battery was charged and discharged under the following conditions as a cell conditioning step. [Conditioning conditions] 1st cycle: Charge: 3mA, 4.2V constant current constant voltage charge, 0.3mA termination ⇒ Discharge: 6mA, discharge, 2.75V termination 2nd cycle: Charge: 6mA, 4.2V, constant current / constant voltage charge, terminates at 0.6mA ⇒ Discharge: 6mA, discharge, terminates at 2.75V 3rd cycle charging: 6 mA, 4.2 V constant current and constant voltage charging, terminated at 0.6 mA ⇒ Discharging: 30 mA discharge, terminated at 2.75 V (2) Characteristic evaluation Using the completed battery obtained in (1) above, the calculation of the DCR increase rate and the measurement of the OCV after high-temperature storage were carried out by the following methods. The results are shown in Tables 3 and 4. <DCR increase rate> The completed battery was charged with a constant current and constant voltage of 30 mA, 4.2 V, terminated at 0.6 mA to reach a fully charged state. The DCR was measured at 25°C from the fully charged state. For the DCR measurement, after waiting for 30 minutes after the completion of full charge, it was discharged at 6 mA (0.2 C) for 10 seconds. After waiting for another 30 minutes, it was discharged at 30 mA (1 C) for 10 seconds. After waiting for another 30 minutes, it was discharged at 90 mA (3 C) for 10 seconds. An I-V straight line was created from the relationship between the voltage difference and current immediately before the start of discharge and 10 seconds later at each discharge current, and its slope was calculated as the DCR. The battery after DCR measurement was subjected to a 45°C cycle test for 700 cycles, and the DCR was measured at 25°C as in the initial case. The cycle conditions were charging: 4.2 V, 30 mA (1 C), terminated at 0.6 mA (0.05 C), 10-minute rest ⇒ Discharging: 30 mA (1 C), terminated at 2.75 V, 10-minute rest. The DCR increase rate was calculated as 100×(DCR after cycle test) / (DCR before cycle test) (%). <OCV after high-temperature storage> For the conditioned cell, a constant current and constant voltage charge of 1 C (30 mA), 4.2 V, terminated at 0.02 C (0.6 mA) was performed at room temperature to reach a fully charged state, and it was stored at 65°C for 31 days. The open circuit voltage (OCV: Open Circuit Voltage) of the cell before and after storage was measured.

[0106]

Table 3

[0107]

Table 4

[0108] Examples 3-51 to 3-75 Finished batteries were fabricated in the same manner as in Examples 3-1 to 3-50, except that the compounds added were changed as shown in Table 5. The DCR increase rate was calculated and the OCV after high-temperature storage was measured in the same manner as in Examples 3-1 to 3-50. Furthermore, the low-temperature discharge retention rate was calculated by the following method. The calculation of the low-temperature discharge retention rate was also performed for Comparative Example 3-1. The results are shown in Table 5. <Low temperature discharge maintenance rate> The battery was charged at 25°C at a constant current of 6 mA and a constant voltage of 4.2 V with a termination of 0.6 mA. After storing the battery at -25°C for 2 hours, the discharge capacity was measured by discharging at a constant current of 30 mA (1C) at -25°C with a termination of 2.75 V. Low temperature discharge capacity retention rate Low-temperature discharge capacity retention rate = 100 × (1C discharge capacity at -25°C) / (1C discharge capacity at 25°C = discharge capacity at the third conditioning cycle) was calculated.

[0109] [Table 5]

[0110] Examples 4-1 to 4-25, Comparative Example 4-1 The DCR increase rate was calculated and the OCV after high-temperature storage was measured in the same manner as in Examples 3-1 to 3-50, except that the compounds added were changed as shown in Table 6. The results are shown in Table 6.

[0111] [Table 6]

[0112] Examples 4-26 to 4-30 The calculation of the DCR increase rate, the OCV measurement after high-temperature storage, and the calculation of the low-temperature discharge capacity retention rate were performed in the same manner as in Examples 3-51 to 3-75, except that the added compounds were changed as shown in Table 7. The calculation of the low-temperature discharge capacity retention rate was also performed for Comparative Example 4-1. The results are shown in Table 7.

[0113] [Table 7]

[0114] Examples 5-1 to 5-36, Comparative Examples 5-1 to 5-7 The DCR increase rate was calculated and the OCV after high-temperature storage was measured in the same manner as in Examples 3-1 to 3-50, except that the concentrations of LiFSI and LiPF6 were changed as shown in Tables 8 and 9 and the compounds to be added were changed as shown in Tables 8 and 9. The results are shown in Tables 8 and 9.

[0115] [Table 8]

[0116] [Table 9]

[0117] Examples 6-1 to 6-36, Comparative Examples 6-1 to 6-7 (1) Preparation of electrodes (Preparation of positive electrode) LiNi, a ternary positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (Beijing Dangsheng Co., Ltd.), acetylene black (AB, Denka Co., Ltd., product name: Denka Black (registered trademark)), graphite (Nippon Graphite Industries Co., Ltd., product number: SP270), and polyvinylidene fluoride (PVdF, Kureha Corporation, product number: KF1120) were dispersed in N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode composite slurry (positive electrode active material: AB: graphite: PVdF = 93:3:3:3 (solid mass ratio)). Subsequently, the obtained positive electrode composite slurry was applied to an aluminum foil (positive electrode current collector, Nippon Foil Co., Ltd., thickness 15 μm) so that the coating weight after drying was 19.4 mg / cm. 2 The mixture was coated on one side with an applicator so that the density was 3.1 g / cm , and then dried on a hot plate at 110°C for 10 minutes. It was then dried in a vacuum drying oven at 110°C for 12 hours. The density was then adjusted to 3.1 g / cm using a roll press. 3The mixture was pressed and molded until a sheet-like positive electrode was obtained. (Preparation of negative electrode) A silicon oxide (SiO) / graphite composite material (manufactured by BTR, product number: BSO-600) as a negative electrode active material, a conductive additive (manufactured by Showa Denko K.K., product number: VGCF-H (registered trademark) and (manufactured by Imerys, product number: Super-P (registered trademark)), styrene-butadiene rubber (SBR, binder), and carboxymethyl cellulose (CMC, binder) were dispersed in ultrapure water to prepare a negative electrode mixture slurry (negative electrode active material: VGCF:Super-P:SBR:CMC = 90:2:3:3:2 (solid content mass ratio)). Subsequently, the obtained negative electrode mixture slurry was applied to a copper foil (negative electrode current collector, manufactured by Fukuda Metal Foil & Powder Co., Ltd., thickness 15 μm) so that the coating weight after drying was 6.8 mg / cm. 2 The mixture was coated on one side with an applicator so that the density was 1.3 g / cm , and then dried on a hot plate at 80°C for 10 minutes. It was then dried in a vacuum drying oven at 100°C for 12 hours. The mixture was then pressed with a roll press to a density of 1.3 g / cm . 3 The mixture was pressed and molded until a sheet-like negative electrode was obtained. (2) Characterization LiFSI and LiPF6 were dissolved in a mixed solvent of EC / fluoroethylene carbonate (FEC) / EMC = 2 / 1 / 7 (vol / vol) to the concentrations shown in Tables 10 and 11, and the compounds of formula (2) shown in Tables 10 and 11 were added in the amounts shown in Tables 10 and 11. Battery evaluations were performed using this electrolyte and the positive and negative electrodes prepared in (1) above under the same conditions as in Examples 3-1 to 3-50. The results are shown in Tables 10 and 11.

[0118] [Table 10]

[0119] [Table 11]

[0120] Examples 7-1 to 7-24, Comparative Examples 7-1 to 7-7 (1) Fabrication of laminated battery The positive electrode active material was changed to commercially available LiFePO4, and acetylene black (HS-100) and PVdF (Kureha #L7208) were weighed at a composition (mass) ratio of 100:9:6 and dispersed in NMP to prepare a slurry. The prepared slurry was applied to one side of an aluminum foil (coating weight 20.20 mg / cm 2 ), dried, and roll-pressed to fabricate a positive electrode. An aqueous slurry with a composition of graphite (SMG / SFG15 = 85 / 15):VGCF:SBR:CMC = 100:2:1.5:1.5 was prepared, and coated on a copper foil at a coating weight of 8.8 mg / cm 2 , dried, and roll-pressed to fabricate a negative electrode. Using the fabricated positive and negative electrodes, 25 mAh laminated batteries were fabricated in the same manner as in Examples 3-1 to 3-50. The electrolytic solution was prepared by dissolving LiFSI and LiPF6 in a mixed solvent of EC / EMC = 3 / 7 (vol / vol) at the predetermined ratios described in Tables 12 and 13, and adding the compounds described in Tables 12 and 13 as the compound of formula (2) at the addition amounts described in Tables 12 and 13. After injecting the electrolyte, a constant current charge of 5 mA for 3 hours was performed, one piece was cracked, and then re-vacuum sealed to remove gas. After storing the cell after gas removal at 25 °C for 48 hours, it was charged and discharged under the following conditioning conditions to complete the evaluation battery. [Conditioning Conditions] First cycle Charge: 2.5 mA 3.6V constant current constant voltage charge terminated at 0.25 mA ⇒ Discharge: 5 mA discharge terminated at 2.0V Second cycle Charge: 2.5 mA 3.6V constant current constant voltage charge terminated at 0.5 mA ⇒ Discharge: 5 mA discharge terminated at 2.0V Third cycle Charge: 2.5 mA 3.6V constant current constant voltage charge terminated at 0.5 mA ⇒ Discharge: 25 mA discharge terminated at 2.0V (2) Characteristic Evaluation Using the evaluation battery obtained in (1) above, the DCR increase rate was calculated and the self-discharge capacity rate after high-temperature storage was measured by the following method. The results are shown in Tables 12 and 13. <DCR Increase Rate> After conditioning, the cells were charged at a constant current of 25 mA, a constant voltage of 3.6 V, and a cutoff voltage of 0.5 mA until the cells reached a fully charged state. The DCR was measured at 25°C from the fully charged state. The DCR measurement was performed as follows. After full charging, the battery was left to stand for 30 minutes, then discharged at 5mA (0.2C) for 10 seconds. After another 30-minute wait, the battery was discharged at 25mA (1C) for 10 seconds. After another 30-minute wait, the battery was discharged at 75mA (3C) for 10 seconds. An IV line was created from the relationship between the difference in voltage immediately before discharge began and 10 seconds after discharge at each discharge current, and the current, and the slope was calculated as the DCR. Then, a 45°C cycle test Cycle conditions: Constant current / constant voltage charge: 25mA, 3.6V, 0.5mA termination ⇒ Constant current discharge: 25mA, discharge, 2.0V termination After 700 cycles, the DCR after the cycles was determined in the same manner as in the initial stage. The DCR increase rate was calculated as 100 × (DCR after the cycle test) / (DCR before the cycle test) (%). <Self-discharge capacity rate measurement after high-temperature storage> The self-discharge amount was calculated as the self-discharge capacity rate after storage at 65°C for 31 days using the following formula. 100 × {(discharge capacity before storage) – (discharge capacity after storage)} / (discharge capacity before storage) The completed battery was charged and discharged under the following conditions (25°C), and the discharge capacity before storage was confirmed. Charge: 3.6V 25mA constant current constant voltage charge 0.5mA termination ⇒ Constant current discharge: 2.5mA 2.0V termination For high temperature storage, after checking the discharge capacity, the cells were charged at room temperature at a constant current and constant voltage of 1C (25mA) and terminated at 0.02C (0.5mA) at 3.6V, and then fully charged and stored at 65°C for 31 days. The discharge capacity after storage was determined by discharging the battery after 31 days of storage at a constant current of 2.5 mA at 25° C. with a cut-off voltage of 2.0 V.

[0121] [Table 12]

[0122] [Table 13]

[0123] Examples 8-1 to 8-10, Comparative Example 8-1 The DCR increase rate was calculated and the OCV after high-temperature storage was measured in the same manner as in Examples 3-1 to 3-50, except that the ratio of EC and EMC in the mixed solvent in the electrolyte was changed as shown in Table 14 and the compounds added were changed as shown in Table 14. The results are shown in Table 14.

[0124] [Table 14]

Claims

1. The following formula (1): MN(R １ SO ２ )(R ２ SO ２ ) (1) (In formula (1), M represents an alkali metal atom. R １ , R ２ and are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, 【Chemical 1】 (In formula (2), R ３ represents a hydrocarbon group which may have a substituent. M' represents a metal atom. a is an integer of 1 or more, and b is the number 1 or 2. c, d, e, and n are the same or different and each is an integer of 1 or more, and c×d=n×e.

2. R in the formula (2) ３ 2. The electrolytic solution according to claim 1, wherein is a hydrocarbon group having 1 to 6 carbon atoms which may have a substituent.

3. 2. The electrolytic solution according to claim 1, wherein the compound represented by formula (2) is contained in an amount of 0.0005 to 1.5% by mass relative to 100% by mass of the electrolytic solution.

4. 2. The electrolyte solution according to claim 1, wherein the sulfonylimide compound represented by the formula (1) is contained in a proportion of 0.01 to 5.0 mol / L.

5. Furthermore, M １ PF ６ , M １ BF ４ , M １ P.O. ２ F ２ , M １ FSO ３ (M １ The electrolyte solution according to claim 1, characterized in that it contains at least one of the following:

6. The following formula (1): MN(R １ SO ２ )(R ２ SO ２ ) (1) (In formula (1), M represents an alkali metal atom. R １ , R ２ and are the same or different and represent a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms, 【Chemistry 2】 (In formula (3), R ４ represents a hydrocarbon group which may have a substituent, or a divalent group formed by linking multiple hydrocarbon groups which may have a substituent via an oxygen atom or a sulfur atom. ５ represents a hydrogen atom or a hydrocarbon group which may have a substituent. ｍ＋ represents a metal cation or an onium cation, R ４ represents an onium cation when f is a hydrocarbon group which may have a substituent; f is an integer of 1 or more, and g is the number 1 or 2; h, i, j, and m are the same or different and each is an integer of 1 or more, and h×i=m×j.

7. R in the formula (3) ４ 7. The electrolytic solution according to claim 6, wherein is a hydrocarbon group having 1 to 6 carbon atoms which may have a substituent.

8. 7. The electrolytic solution according to claim 6, wherein the compound represented by formula (3) is contained in an amount of 0.0005 to 1.5% by mass relative to 100% by mass of the electrolytic solution.

9. 7. The electrolytic solution according to claim 6, wherein the sulfonylimide compound represented by the formula (1) is contained in a proportion of 0.01 to 5.0 mol / L.

10. Furthermore, M １ PF ６ , M １ BF ４ , M １ P.O. ２ F ２ , M １ FSO ３ (M １ represents an alkali metal atom.

11. A battery comprising the electrolyte solution according to any one of claims 1 to 10.

12. The battery has the following formula (5): L)) ｘ Co ｙ Mn ｚ O ２ (5) (wherein x, y, and z are numbers satisfying x+y+z=1, 0≦x≦1, 0≦y≦1, and 0≦z≦1) and / or LiFePO ４ The battery of claim 11 , comprising a positive electrode comprising:

13. 13. The battery according to claim 12, wherein the battery is configured to include a negative electrode active material containing Si.

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