Method for purifying sulfonimide aqueous solution, method for producing nonaqueous electrolyte, and method for producing electrolyte composition

Abstract

A method for purifying a sulfimine aqueous solution includes a heating step in which a sulfimine aqueous solution containing a sulfimine compound represented by general formula (1) is subjected to a heating treatment. In a method for producing a nonaqueous electrolyte, an electrolyte solvent is added to the sulfimine aqueous solution purified by the purification method and subjected to dehydration. A method for producing an electrolyte composition includes a step of removing an electrolyte solvent from a nonaqueous electrolyte obtained by the production method by distillation. LiN(RSO2)(FSO2) (R represents a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms.)(1).

Description

Technical Field

[0001] This disclosure relates to a method for purifying an aqueous sulfonamide solution, a method for manufacturing a non-aqueous electrolyte, and a method for manufacturing an electrolyte composition. Background Technology

[0002] To improve the performance of secondary batteries such as lithium-ion batteries, various studies have been conducted on non-aqueous electrolytes and their materials used in secondary batteries. For example, Patent Document 1 proposes a solution containing a solution of a non-protic solvent with the formula Li + [(FSO2)2N] － Lithium bis(fluorosulfonyl)imide (hereinafter also referred to as "LiFSI") is an ionic conductive material of an ionic compound.

[0003] Patent Document 1: Japanese Patent No. 3878206 Summary of the Invention

[0004] -The technical problem the invention aims to solve-

[0005] However, as a byproduct of the synthesis of sulfonylimide compounds such as LiFSI, or as a decomposition product of LiFSI, FSO3Li (lithium fluorosulfonate) is generated. FSO3Li decomposes in a small amount of water to produce SO4. 2－ Impurities such as sulfate ions promote the decomposition of LiFSI. As a result, LiFSI deteriorates.

[0006] In addition, Patent Document 1 states that FSO3Li is unstable in cyclic ether solutions and decomposes into LiF and SO3 in cyclic ethers.

[0007] Therefore, considering the storage stability of LiFSI, it is preferable to keep the concentration of FSO3Li in LiFSI low, but Patent Document 1 does not describe a method for reducing FSO3Li.

[0008] This disclosure was made to solve the above-mentioned problems, and its object is to provide a purification method for reducing the concentration of FSO3Li in an aqueous solution of sulfonylimide containing a sulfonylimide compound, a method for manufacturing a non-aqueous electrolyte using the aqueous solution of sulfonylimide purified by the purification method, and a method for manufacturing an electrolyte composition using the non-aqueous electrolyte obtained by the manufacturing method.

[0009] - Technical solutions for solving technical problems -

[0010] To achieve the above objectives, in this disclosure, after preparing the sulfonamide aqueous solution, a simple method is used to reduce the concentration of FSO3Li in the sulfonamide aqueous solution through slight treatment. The specific details of this disclosure are as follows.

[0011] The purification method for the sulfonylimide aqueous solution disclosed herein includes a heating step in which an aqueous solution containing a sulfonylimide compound represented by general formula (1) is heated. The heating step can be performed at a temperature between 60°C and 120°C. The heating step can also be performed at a pressure below 30 kPa. The concentration of FSO3Li in the aqueous solution of the sulfonylimide after the heating step can be less than 1500 ppm by mass relative to the sulfonylimide compound represented by general formula (1).

[0012] LiN(RSO2)(FSO2)(R represents a fluorine atom, an alkyl group with 1 to 6 carbon atoms, or a fluoroalkyl group with 1 to 6 carbon atoms)(1)

[0013] The method for manufacturing the non-aqueous electrolyte disclosed herein is a method for manufacturing a non-aqueous electrolyte containing a sulfonylimide compound represented by the general formula (1) as an electrolyte and an electrolyte solvent. The electrolyte solvent is added to an aqueous sulfonylimide solution purified by the purification method, and the solution is then dehydrated. The electrolyte solvent can be a carbonate solvent. The concentration of FSO3Li in the non-aqueous electrolyte can be less than 100 ppm by mass relative to the electrolyte.

[0014] The method for manufacturing the electrolyte composition disclosed herein is a method for manufacturing an electrolyte composition containing a sulfonylimide compound represented by the general formula (1) as an electrolyte, comprising a step of removing the electrolyte solvent from a non-aqueous electrolyte obtained by the manufacturing method by distillation, wherein the concentration of FSO3Li in the electrolyte composition is less than 100 ppm by mass relative to the electrolyte.

[0015] -The effects of the invention-

[0016] According to this disclosure, a purification method for reducing the concentration of FSO3Li in an aqueous sulfonylimide containing a sulfonylimide compound, a method for manufacturing a non-aqueous electrolyte using the purified aqueous sulfonylimide solution obtained by the purification method, and a method for manufacturing an electrolyte composition using the non-aqueous electrolyte obtained by the manufacturing method are provided. Attached Figure Description

[0017] Figure 1 This is a graph showing the change of FSO3Li concentration in the LiFSI aqueous solution obtained in Example 3 over time. Detailed Implementation

[0018] The following is a detailed description of this embodiment. The description of the preferred embodiments is merely illustrative and is not intended to limit the invention, its application, or its uses.

[0019] <Refining Method of Sulfonamide Aqueous Solution>

[0020] The purpose of the purification method for sulfonylimide aqueous solution according to this embodiment is to reduce the concentration of FSO3Li in the sulfonylimide aqueous solution containing the specific sulfonylimide compound described below. By reducing the concentration of FSO3Li in the sulfonylimide aqueous solution, SO42- can be suppressed. 2－ This process reduces the formation of impurities (decomposition products of FSO3Li) that promote the decomposition of sulfonylimide compounds. As a result, it inhibits the deterioration of the sulfonylimide aqueous solution. The sulfonylimide aqueous solution purified by this method has a reduced amount of these impurities, thus improving its storage stability (its ability to suppress decomposition reactions of sulfonylimide compounds even under long-term storage). Therefore, this sulfonylimide aqueous solution is well-suited for use as a raw material for non-aqueous electrolytes (electrolyte solutions, electrolyte materials).

[0021] (Heating process)

[0022] The purification method for sulfonamide aqueous solutions includes a heating step that heats the sulfonamide aqueous solution. Specifically, the heating step is performed after the preparation step of the sulfonamide aqueous solution. Thus, this purification method is characterized by setting a heating step after the preparation step. By heating the sulfonamide aqueous solution, impurities (especially FSO3Li) in the sulfonamide aqueous solution can be significantly reduced.

[0023] There are no particular limitations on the method for heating the aqueous solution of sulfonamide; any existing known method can be used. For example, a method of heating a container containing the aqueous solution of sulfonamide while stirring (heating and stirring method) can be listed. Specifically, a container such as a flask or test tube containing the aqueous solution of sulfonamide is immersed in an oil bath, and the temperature of the oil bath is raised while stirring, thereby raising the temperature inside the container (equivalent to the heat treatment temperature described below).

[0024] The heating process can be carried out under either atmospheric pressure or reduced pressure (or a combination of atmospheric and reduced pressure). When the heating process is carried out under reduced pressure, the pressure is not particularly limited, as long as it is appropriately adjusted according to the concentration of the sulfonamide compound, the type and amount of the anionic component and additives described below. For example, it is preferably 100 kPa or less, more preferably 60 kPa or less, further preferably 30 kPa or less, and particularly preferably 15 kPa or less. Furthermore, the lower limit of the pressure exceeds 10 kPa. It should be noted that the pressure in the heating process can be constant or varied within the above-mentioned range.

[0025] The higher the heat treatment temperature in the heating process, the greater the reduction rate of FSO3Li concentration in the sulfonylimide aqueous solution, and the higher the storage stability of the sulfonylimide aqueous solution and the non-aqueous electrolyte prepared using this aqueous solution. From this perspective, the heat treatment temperature is preferably 60°C or higher, more preferably 70°C or higher, further preferably 80°C or higher, and even more preferably 90°C or higher. From the viewpoint of suppressing the thermal deterioration of the sulfonylimide aqueous solution caused by the thermal decomposition of the sulfonylimide compound, the upper limit of the heat treatment temperature is preferably 120°C or lower.

[0026] The heating time in the heating process can be appropriately determined based on the concentration of the sulfonylimide compound in the sulfonylimide aqueous solution. A longer heating time will increase the rate of reduction of the FSO3Li concentration in the sulfonylimide aqueous solution. Heating times can be, for example, 3 hours or more, 5 hours or more, or 6 hours or more. Furthermore, from the perspective of production efficiency of the sulfonylimide aqueous solution, the upper limit of the heating time is 24 hours or less.

[0027] From the viewpoint of improving the storage stability of the sulfonylimide aqueous solution and the non-aqueous electrolyte prepared using the aqueous solution, the concentration of FSO3Li in the sulfonylimide aqueous solution after the heating process is preferably 1500 ppm (0.15% by mass) or less, more preferably 1000 ppm (0.10% by mass) or less, even more preferably 500 ppm (0.05% by mass) or less, even more preferably 300 ppm (0.03% by mass) or less, even more preferably 100 ppm (0.01% by mass) or less, and particularly preferably 50 ppm (0.005% by mass) or less. A lower FSO3Li concentration is preferred; the FSO3Li concentration may be below the detection limit or substantially free of FSO3Li (0 ppm by mass). The FSO3Li concentration can be measured by the methods described in the examples below, such as ion chromatography.

[0028] From the viewpoint of improving the storage stability of sulfonylimide aqueous solution and the non-aqueous electrolyte prepared using the aqueous solution, a higher rate of reduction in the concentration of FSO3Li in the sulfonylimide aqueous solution before and after the heating process (before and after heat treatment) is preferred, for example, preferably 50% or more, more preferably 60% or more. It should be noted that this reduction rate can be calculated, for example, by the following formula (1).

[0029] [Formula 1]

[0030] The decrease rate of FSO3Li concentration in the sulfonamide aqueous solution before and after heat treatment = [{(FSO3Li concentration in the sulfonamide aqueous solution before heat treatment) - (FSO3Li concentration in the sulfonamide aqueous solution after heat treatment)} / (FSO3Li concentration in the sulfonamide aqueous solution before heat treatment)] × 100 (1)

[0031] (Preparation process)

[0032] The purification method for sulfonamide aqueous solution may include a preparation step performed before the heating step, or other steps, such as a step in the manufacturing method of sulfonamide aqueous solution. Thus, from the perspective of producing a high-purity sulfonamide aqueous solution, the purification method for sulfonamide aqueous solution can also be described as the manufacturing method of sulfonamide aqueous solution. The preparation step is the step of preparing an aqueous solution of sulfonamide containing a fluorinated sulfonamide salt of a sulfonamide compound represented by general formula (1) (hereinafter referred to as "sulfonamide compound (1)").

[0033] [Chemical Formula 1]

[0034] LiN(RSO2)(FSO2)(1)

[0035] In general formula (1), R represents a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms.

[0036] Examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl. Among alkyl groups having 1 to 6 carbon atoms, straight-chain or branched alkyl groups having 1 to 6 carbon atoms are preferred, and straight-chain alkyl groups having 1 to 6 carbon atoms are more preferred.

[0037] Examples of fluoroalkyl groups having 1 to 6 carbon atoms include fluoroalkyl groups in which some or all of the hydrogen atoms are replaced by fluorine atoms. Examples of fluoroalkyl groups having 1 to 6 carbon atoms include fluoromethyl, difluoromethyl, trifluoromethyl, fluoroethyl, difluoroethyl, trifluoroethyl, pentafluoroethyl, etc. In particular, fluoroalkyl groups can be perfluoroalkyl groups.

[0038] As a substituent R, it is preferably a fluorine atom and a perfluoroalkyl group (e.g., perfluoroalkyl groups with 1 to 6 carbon atoms such as trifluoromethyl, pentafluoroethyl, and heptafluoropropyl), more preferably a fluorine atom, trifluoromethyl, and pentafluoroethyl, even more preferably a fluorine atom and trifluoromethyl, and even more preferably a fluorine atom.

[0039] Specific examples of sulfonylimide compounds (1) include: lithium bis(fluorosulfonyl)imide (LiN(FSO2)2, LiFSI), lithium (fluorosulfonyl)(methylsulfonyl)imide, lithium (fluorosulfonyl)(ethylsulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, lithium (fluorosulfonyl)(pentafluoroethylsulfonyl)imide, lithium (fluorosulfonyl)(heptafluoropropylsulfonyl)imide, etc. Sulfonylimide compounds can be used individually or in combination.

[0040] From the viewpoint of sufficiently reducing FSO3Li in the aqueous solution of sulfonylimide, lithium bis(fluorosulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, and lithium (fluorosulfonyl)(pentafluoroethylsulfonyl)imide are preferred in the sulfonylimide compound (1), with lithium bis(fluorosulfonyl)imide being more preferred. In other words, in the aqueous solution of sulfonylimide, it is preferred that the sulfonylimide compound (1) contains LiN(FSO2)2.

[0041] The sulfonamide compound (1) can be a commercially available product or a compound synthesized by existing known methods. There are no particular limitations on the method for synthesizing the sulfonamide compound (1), and all existing known methods can be used. Examples include: International Patent Publication No. 2011 / 149095, Japanese Patent Publication No. 2014-201453, Japanese Patent Publication No. 2010-168249, Japanese Patent Publication No. 2010-168308, Japanese Patent Publication No. 2010-189372, International Patent Publication No. 2011 / 065502, and Japanese Patent Publication No. 8-511. The methods described in Japanese Patent Publication No. 274, International Publication No. 2012 / 108284, International Publication No. 2012 / 117961, International Publication No. 2012 / 118063, Japanese Patent Publication No. 2010-280586, Japanese Patent Publication No. 2010-254543, Japanese Patent Publication No. 2007-182410, and International Publication No. 2010 / 010613, etc., can be used to obtain a powder (solid) of sulfonamide compound (1).

[0042] From the viewpoint of sufficiently reducing FSO3Li, the content of sulfonylimide compound (1) in the aqueous sulfonylimide solution (total content when two or more are used simultaneously) is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more. From the viewpoint of sufficiently reducing FSO3Li, the upper limit of this content is preferably 80% by mass or less.

[0043] Without prejudice to the purpose of this invention, the sulfonamide compound (1) (sulfonamide aqueous solution) may contain the manufacturing solvent used in the manufacture of the sulfonamide compound (1) (the residual solvent contained in the sulfonamide compound (1) obtained by the above-described conventional known method). The residual solvent refers to the solvent used in the manufacturing reaction of the sulfonamide compound (1), the solvent used in the purification process, etc. Examples include: water; alcohol solvents such as methanol, ethanol, propanol, and butanol; carboxylic acid solvents such as formic acid and acetic acid; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone; nitrile solvents such as isobutyronitrile, acetonitrile, valerate, and benzonitrile; ester solvents such as ethyl acetate, isopropyl acetate, and butyl acetate; aliphatic ether solvents such as diethyl ether, diisopropyl ether, tert-butyl methyl ether, and cyclopentyl methyl ether; halogen solvents such as HF; nitro-containing solvents such as nitromethane and nitrobenzene; and nitrogen-containing organic solvents such as ethylformamide and N-methylpyrrolidone. Dimethyl sulfoxide; glycol dimethyl ether solvents; toluene, o-xylene, m-xylene, p-xylene, benzene, ethylbenzene, isopropylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tetrahydronaphthalene, methyl isopropylbenzene, methyl ethylbenzene, 2-ethyltoluene, chlorobenzene, dichlorobenzene, and other aromatic hydrocarbon solvents; pentane, hexane, heptane, octane, decane, dodecane, undecane, tridecane, decahydronaphthalene, 2,2,4,6,6-pentamethylheptane, isoparaffins (e.g., "Marukasol R" (a mixture of 2,2,4,6,6-pentamethylheptane and 2,2,4,4,6-pentamethylheptane manufactured by Maruzen Petrochemical Co., Ltd.), "ISOPAR" TM G (C9-C11 mixed isoparaffins produced by ExxonMobil), "ISOPAR" TME (C8-C10 mixed isoparaffins manufactured by Exxon Mobil), dichloromethane, chloroform, 1,2-dichloroethane and other chain aliphatic hydrocarbon solvents; cyclohexane, methylcyclohexane, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, ethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane, propylcyclohexane, butylcyclohexane, "Swaclean" 150" (a mixture of C9 alkylcyclohexanes manufactured by Maruzen Petrochemical Co., Ltd.) and other cyclic aliphatic hydrocarbon solvents; aromatic ether solvents such as anisole, 2-methyl anisole, 3-methyl anisole, and 4-methyl anisole; carbonate solvents such as ethylene carbonate, propylene carbonate, butene carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; chain ether solvents such as dimethoxymethane and 1,2-dimethoxyethane; cyclic ether solvents such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxane, and 4-methyl-1,3-dioxolane; cyclic ester solvents such as γ-butyrolactone and γ-valerolactone; sulfolane solvents such as sulfolane and 3-methylsulfolane; N,N-dimethylformamide, dimethyl sulfoxide, and N-methyloxazolidinone, etc.

[0044] In other words, without impairing the purpose of the present invention, the aqueous solution of sulfonamide may also contain non-aqueous solvents such as the aforementioned residual solvent. Furthermore, without impairing the purpose of the present invention, during the preparation process (before the heating process), non-aqueous solvents such as the following electrolyte solvents may be added to the aqueous solution of sulfonamide. Preferably, the added non-aqueous solvents are chain carbonate (chain carbonate) solvents, ether solvents, chain ester solvents, and nitrile solvents; more preferably, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, ethyl acetate, butyl acetate, propyl propionate, acetonitrile, propionitrile, valerate, butyronitrile, and isobutyronitrile; and even more preferably, chain carbonate solvents such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate.

[0045] Without prejudice to the purpose of this invention, the aqueous solution of sulfonamide may also contain the following additives. In other words, additives may be added to the aqueous solution of sulfonamide during the preparation process.

[0046] Furthermore, without prejudice to the purpose of this invention, the sulfonamide aqueous solution may also contain anionic components. In other words, anionic components may be added to the sulfonamide aqueous solution during the preparation process. During the preparation of the sulfonamide aqueous solution, some fluorosulfonic acid (HFSO3) is generated due to water in the aqueous solution, heat generated during dissolution, etc. In addition, depending on the manufacturing method of the sulfonamide compound (1), in some cases, the obtained sulfonamide compound (1) itself contains HFSO3. HFSO3, like FSO3Li, is a cause of decomposition of the sulfonamide compound (1) and thus deterioration of the sulfonamide aqueous solution. Therefore, it is preferable to use anionic components to trap HFSO3 in the sulfonamide aqueous solution.

[0047] An anionic component contains an acid component with an acid dissociation constant pKa (for multi-step ionized acids, the first-step acid dissociation constant pKa1) of 0 to 6.5 (temperature: room temperature (25°C), solvent: water) (hereinafter also referred to as "specific acid component").

[0048] It should be noted that, in this specification, anionic components refer to a portion of the structure of a specific acid component (e.g., aminosulfonic acid, as described below) or its salt (e.g., lithium aminosulfonate, as described below) that can become an anion through ion dissociation in solution (in the case of the above example, it is the aminosulfonate ion).

[0049] The pKa (pKa1) of a specific acid component is greater than that of sulfuric acid (pKa1 = -3) produced by the decomposition of sulfonamide compound (1). Examples of specific acid components include: aminosulfonic acid (pKa = 1), acetic acid (pKa = 4.8), carbonic acid (pKa1 = 6.1), and phosphoric acid (pKa1 = 1.8). Specific acid components can be used individually (can be contained alone) or two or more can be used simultaneously (can be contained in combination). That is, the specific acid component (anionic component) is at least one selected from the group consisting of aminosulfonic acid, acetic acid, carbonic acid, and phosphoric acid. In addition, the structure of the specific acid component in solution is not particularly limited; it can exist in ionic form (contained) (can be insoluble) or be soluble in solution.

[0050] Examples of aminosulfonic acid components (aminosulfonic acid compounds, aminosulfonic acid derivatives, aminosulfonic acid derivatives) include: aminosulfonic acid (aminosulfuric acid), aminosulfonic acid derivatives, and their salts.

[0051] The structure of aminosulfonic acid components is not particularly limited; for example, it can be neutral (H2NSO2(OH), HN=SO(OH)2, etc.) or zwitterionic (H3N +SO3 － H2N + =SO(OH)O － (etc.), or it can be a structure that contains both neutral and zwitterionic types.

[0052] As aminosulfonic acid derivatives, they include N-substituted aminosulfonic acids (N-substituted aminosulfuric acid, etc.).

[0053] Such aminosulfonic acid derivatives (and their salts) can be compounds represented by general formula (2) (N-substituted aminosulfonic acids and their salts). It should be noted that although general formula (2) uses the neutral type (R... 1 R 2 It can be represented by NSO2(OM), but it can also be zwitterionic, or it can contain both neutral and zwitterionic forms.

[0054] [Chemical Formula 2]

[0055]

[0056] In general formula (2), R 1 R 2 R represents H (hydrogen atom), hydroxyl group, or alkyl groups having 1 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, aryl groups having 6 to 16 carbon atoms, aralkyl groups having 7 to 16 carbon atoms, and alkanoyl groups having 2 to 16 carbon atoms, which may each have substituents. 1 R 2 It can contain heteroatoms, or it can be composed of R 1 and R 2 Forming a ring structure, when R 1 R 2 When R is any of the above groups other than H, 1 R 2 It can be the same type of group or different types of groups (when R...). 1 R 2 If one of them is H, then the other is not H (R) 1 and R 2 (Not both H). M represents H (hydrogen atom) or a metal atom.

[0057] In general formula (2), alkyl groups having 1 to 10 carbon atoms can include methyl, etc. Cycloalkyl groups having 3 to 10 carbon atoms can include cyclopropyl, etc. Aryl groups having 6 to 16 carbon atoms can include phenyl, naphthyl, etc. Aralkyl groups having 7 to 16 carbon atoms can include benzyl, phenethyl, etc. Alkyl groups having 2 to 16 carbon atoms can include benzoyl, etc.

[0058] These can be groups containing heteroatoms (nitrogen, oxygen, sulfur, phosphorus, etc.). Examples of such groups include: groups in which some carbon atoms are replaced by heteroatoms, and thiocycloalkyl groups (groups corresponding to thiocycloalkanes such as thiocycloheptane, thiocyclooctane, thiocyclobutane, thiocyclohexane, and dithiocyclohexane).

[0059] Substituents that replace these groups are not particularly limited, but can include: hydroxyl, halogen atom, amino, carboxyl, alkoxy, acyl, etc. These substituents can be substituted individually or in combination of two or more.

[0060] As metallic atoms, examples include: alkali metal atoms such as lithium, sodium, and potassium; alkaline earth metal atoms such as magnesium, calcium, and barium; and aluminum, etc.

[0061] Specific aminosulfonic acid derivatives and their salts [N-substituted aminosulfonic acids and their salts (or compounds represented by formula (2) above)] can be listed as: N-hydroxyaminosulfonic acid; N-monoalkyl or dialkyl aminosulfonic acid [N-methylaminosulfonic acid, N-ethylaminosulfonic acid, N-(1-methylpropyl)aminosulfonic acid, N-(2-methylbutyl)aminosulfonic acid, N-(2,2-dimethylpropyl)aminosulfonic acid, N,N-diethylaminosulfonic acid, N-(3-hydroxypropyl)aminosulfonic acid, N-methyl-N-(2-(2-methylpropyl)aminosulfonic acid, N ... [N,N-dihydroxypropyl)aminosulfonic acid, N,N-bis(2-hydroxyethyl)aminosulfonic acid, N-(2,3-dihydroxypropyl)aminosulfonic acid, N-(3-methoxy-4-methylphenyl)aminosulfonic acid, N-methyl-N-(2-hydroxy-3-chloropropyl)aminosulfonic acid, N-(2-hydroxy-3-chloropropyl)aminosulfonic acid, N-ethyl-N-(2-hydroxy-3-chloropropyl)aminosulfonic acid, etc.]; N-monocycloalkyl or bicycloalkyl aminosulfonic acids (N-cyclohexylaminosulfonic acid, N,N-dicyclohexylaminosulfonic acid, etc.) (e.g., acids); N-monoaryl or diarylaminosulfonic acids [N-phenylaminosulfonic acid, N-naphthylaminosulfonic acid, N-hydroxy-N-(2-hydroxy-1-naphthyl)aminosulfonic acid, N-(4-bromophenyl)aminosulfonic acid, etc.]; N-monoaryl or diarylarylaminosulfonic acids [N-benzylaminosulfonic acid, N-(β-methylphenylethyl)aminosulfonic acid, etc.]; N-alkyl-N-arylaminosulfonic acids (N-ethyl-N-phenylaminosulfonic acid, etc.); N-monoacyl or diacylaminosulfonic acids [N-benzoylaminosulfonic acid, N-(3-methylphenylethyl)aminosulfonic acid, N-(4-bromophenyl)aminosulfonic acid, etc.]; [N-(3-chloro-3-methylpropanoyl)aminosulfonic acid, N-(3-chloro-3-methylpropanoyl)aminosulfonic acid, etc.]; N-thiocycloalkylaminosulfonic acids [N-(thiocycloheptane-4-yl)aminosulfonic acid, N-thiocyclooctane-4-ylaminosulfonic acid, thiocyclooctane-5-ylaminosulfonic acid, N-thiocyclobutane-3-ylaminosulfonic acid, N-1,3-dithiocyclohexane-5-ylaminosulfonic acid, N-(thiocyclohexane-3-yl)aminosulfonic acid, N-(thiocyclopentane-3-yl)aminosulfonic acid, etc.]; and their salts, etc. Aminosulfonic acid derivatives and their salts can be used individually or in combination.

[0062] There are no particular limitations on the salts that are components of aminosulfonic acid. For example, they can be salts of aminosulfonic acid or aminosulfonic acid derivatives as bases or acids. Usually, they can be salts of aminosulfonic acid or aminosulfonic acid derivatives as acids (salts composed of aminosulfonic acid or aminosulfonic acid derivatives and bases).

[0063] Specific examples of salts include: alkali metal salts such as lithium, sodium, and potassium salts; alkaline earth metal salts such as magnesium, calcium, and barium salts; and metal salts such as aluminum salts. Alkali metal salts are preferred, and lithium salts are more preferred. The salt can also be a salt corresponding to the cation of the combined electrolyte. For example, when using lithium salts as the electrolyte, lithium salts (such as lithium sulfamate) can also be used.

[0064] As a sulfamic acid component, it is preferred to have an sulfamic acid component containing at least one selected from sulfamic acid and its salt (alkali metal salt), sulfamic acid derivatives and their salts (alkali metal salt), more preferably an sulfamic acid component containing at least one selected from sulfamic acid and alkali metal salts of sulfamic acid (e.g., lithium sulfamate), and even more preferably an sulfamic acid component containing an alkali metal salt of sulfamic acid.

[0065] Carboxylic acids and their salts that represent acetic acid can be compounds represented by general formula (3).

[0066] [Chemical Formula 3]

[0067] R 3 COOM(3)

[0068] In general formula (3), R 3 H represents hydrogen atom, and R represents alkyl groups with 1 to 10 carbon atoms, cycloalkyl groups with 3 to 10 carbon atoms, aryl groups with 6 to 16 carbon atoms, aralkyl groups with 7 to 16 carbon atoms, and alkanoyl groups with 2 to 16 carbon atoms, which may each have substituents. 3 It may contain heteroatoms. M is the same as above.

[0069] In general formula (3), methyl and other compounds can be listed as alkyl groups having 1 to 10 carbon atoms. Cycloalkyl groups having 3 to 10 carbon atoms can be listed as cyclopropyl and other compounds. Aryl groups having 6 to 16 carbon atoms can be listed as phenyl, naphthyl, etc. Aryl groups having 7 to 16 carbon atoms can be listed as benzyl, phenethyl, etc. Alkyl groups having 2 to 16 carbon atoms can be listed as benzoyl and other compounds.

[0070] These can be groups containing heteroatoms (nitrogen, oxygen, sulfur, phosphorus, etc.). Examples of such groups include: groups in which some carbon atoms are replaced by heteroatoms, and thiocycloalkyl groups (groups corresponding to thiocycloalkanes such as thiocycloheptane, thiocyclooctane, thiocyclobutane, thiocyclohexane, and dithiocyclohexane).

[0071] Substituents that replace these groups are not particularly limited, but can include: hydroxyl, halogen atom, amino, carboxyl, alkoxy, acyl, etc. These substituents can be substituted individually or in combination of two or more.

[0072] Specific carboxylic acids and their salts (or compounds represented by the above general formula (3)) can be listed as follows: saturated fatty acids (formic acid, acetic acid, propionic acid, butyric acid, etc.), unsaturated fatty acids (linolenic acid, linoleic acid, oleic acid, etc.), hydroxy acids (lactic acid, citric acid, salicylic acid, etc.), dicarboxylic acids (oxalic acid, tartaric acid, phthalic acid, itaconic acid, maleic acid, etc.), amino acids (glycine, alanine, etc.), and their salts. Carboxylic acids and their salts can be used individually or in combination.

[0073] Specific examples of salts include: alkali metal salts (lithium, sodium, potassium, etc.), alkaline earth metal salts (magnesium, calcium, barium, etc.), and aluminum salts. Alkali metal salts are preferred, and lithium salts are more preferred. The salt can also be a salt corresponding to the cation of the combined electrolyte. For example, when using a lithium salt as the electrolyte, lithium salts (such as lithium acetate) can also be used.

[0074] As a carbonic acid component, there are no particular limitations; examples include carbonates and bicarbonates. Carbonic acid components can be used individually or in combination.

[0075] Specific examples of salts include alkali metal salts (lithium, sodium, potassium, rubidium, cesium, etc.) and alkaline earth metal salts (beryllium, magnesium, calcium, strontium, barium, etc.). Alkali metal salts are preferred, and lithium salts are more preferred. The salt can also be a salt corresponding to the cation of the combined electrolyte. For example, when using lithium salts as the electrolyte, lithium salts (such as lithium carbonate) can also be used.

[0076] There are no particular limitations on phosphoric acid components; examples include phosphates, hydrogen phosphates, and dihydrogen phosphates. Phosphoric acid components can be used individually or in combination.

[0077] Specific examples of salts include alkali metal salts (lithium, sodium, potassium, rubidium, cesium, etc.) and alkaline earth metal salts (beryllium, magnesium, calcium, strontium, barium, etc.). Alkali metal salts are preferred, and lithium salts are more preferred. The salt can also be a salt corresponding to the cation of the combined electrolyte. For example, when using lithium salts as the electrolyte, lithium salts (such as lithium phosphate) can also be used.

[0078] The amount of anionic component added to the sulfonamide aqueous solution can be appropriately determined based on the concentration of the sulfonamide compound (1). However, from the viewpoint of reliably capturing HFSO3, when the sulfonamide aqueous solution is 100% by mass, this amount is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more. From the viewpoint of reducing the amount of insoluble particles of the anionic component remaining in the sulfonamide aqueous solution, when the sulfonamide aqueous solution is 100% by mass, the upper limit of this amount is preferably 1% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.5% by mass or less.

[0079] It should be noted that when the specific acid component is a salt (a salt of an acid or its derivatives), the above-mentioned addition amount can also be converted to a proportion in a non-salt form (or free form, such as an acid or its derivatives). The aforementioned acid and its derivative salts can be commercially available or manufactured salts.

[0080] There are no particular limitations on the method for preparing aqueous solutions of sulfonylimide, but examples include: dissolving the powder (solid) of sulfonylimide compound (1) in water; and mixing water, lithium salts such as LiOH or Li2CO3, and HFSI [bis(fluorosulfonyl)imide] and reacting them (preparing an aqueous solution of LiFSI), etc. The aforementioned non-aqueous electrolyte, additives, anionic components, etc., may also be added to the obtained aqueous solution of sulfonylimide as needed.

[0081] (Other processes)

[0082] Without prejudice to the purpose of this invention, the purification method for the aqueous sulfonamide may also include other steps. Examples of other steps include filtration, column chromatography, activated carbon treatment, and molecular sieve treatment.

[0083] <Method for Manufacturing Non-Aqueous Electrolytes>

[0084] The method for manufacturing a non-aqueous electrolyte according to this embodiment is a method for manufacturing a non-aqueous electrolyte containing a sulfonylimide compound (1) as an electrolyte and an electrolyte solvent. This manufacturing method is based on using a sulfonylimide aqueous solution refined by the above-described refining method, and includes a step of adding an electrolyte solvent to the aqueous solution and performing dehydration (hereinafter referred to as the dehydration step). Furthermore, from the perspective of using the refined sulfonylimide aqueous solution as a raw material, the above-described refining method for the sulfonylimide aqueous solution can also be included in one step of the non-aqueous electrolyte manufacturing method. That is, the non-aqueous electrolyte manufacturing method can also be described as a manufacturing method including a preparation step, a heating step, and a dehydration step. In the preparation step, a sulfonylimide aqueous solution is prepared; in the heating step, the sulfonylimide aqueous solution obtained from the preparation step is heated; and in the dehydration step, the sulfonylimide aqueous solution after the heating step is dehydrated to perform solvent replacement, replacing water with the electrolyte solvent. All matters described in the above-described refining method for the sulfonylimide aqueous solution also apply to the non-aqueous electrolyte manufacturing method.

[0085] (Dehydration process)

[0086] The dehydration process is as follows: the following electrolyte solvent is added to the sulfonamide aqueous solution after heat treatment (the sulfonamide aqueous solution refined by the above-mentioned refining method), and the water contained in the sulfonamide aqueous solution and the added electrolyte solvent are removed by azeotropic reaction to dehydrate the solution, thereby replacing the water with the added electrolyte solvent.

[0087] There are no particular limitations on the method for dehydrating aqueous sulfonamide solutions. For example, methods for dehydrating solutions obtained by adding non-aqueous solvents such as electrolyte solvents to aqueous sulfonamide solutions (the solutions used for the operation of "dehydration to replace with non-aqueous solvents", hereinafter also referred to as "aqueous sulfonamide solutions for dehydration") can be listed.

[0088] For example, in the case of azeotropic distillation of water contained in the aqueous sulfonylimide solution for dehydration and the added non-aqueous solvent, the same amount of non-aqueous solvent as the distillate to be removed from the azeotropic distillate can be continuously added to the aqueous sulfonylimide solution for dehydration; or the distillate can be subjected to phase separation to remove the aqueous phase and reflux the organic phase. Through these operations, the aqueous sulfonylimide solution for dehydration is dehydrated to obtain a sulfonylimide solution containing the added non-aqueous solvent. Since the sulfonylimide solution contains an electrolyte (sulfonylimide compound (1)) and an electrolyte solvent, the sulfonylimide solution can be used directly as a non-aqueous electrolyte or as a raw material (electrolyte solution, electrolyte material) for a non-aqueous electrolyte. In this way, the dehydration process can also be described as a process of replacing water in the aqueous sulfonylimide solution with a non-aqueous solvent.

[0089] There is no particular limitation on the lower limit of the amount of electrolyte solvent added (used), which can be appropriately adjusted according to the type and amount of residual solvent in the sulfonamide compound (1). For example, relative to 100g of sulfonamide compound (1), the amount of electrolyte solvent added (used) is preferably 10,000g or less, more preferably 1,000g or less, further preferably 500g or less, and even more preferably 200g or less.

[0090] Additionally, for example, the amount of electrolyte solvent added (used) relative to 100 parts by mass of sulfonylimide compound (1) is preferably 1 to 1000 parts by mass, more preferably 5 to 500 parts by mass, further preferably 10 to 300 parts by mass, and even more preferably 30 to 200 parts by mass.

[0091] The dehydration process can be carried out under either atmospheric pressure or reduced pressure (or a combination of atmospheric and reduced pressure in the dehydration process), but from the viewpoint of suppressing the thermal degradation of the sulfonylimide aqueous solution caused by the thermal decomposition of the sulfonylimide compound (1), it is preferable to carry out the dehydration process under reduced pressure. The pressure can be appropriately adjusted according to the concentration of the sulfonylimide compound (1), the type and amount of the added electrolyte solvent, etc., and is not particularly limited. For example, it is preferably 100 kPa or less, more preferably 40 kPa or less, further preferably 15 kPa or less, and particularly preferably 10 kPa or less.

[0092] The heating temperature in the dehydration process can be adjusted appropriately according to the pressure reduction, the type and amount of electrolyte solvent added, etc., and is not particularly limited. However, from the viewpoint of suppressing the thermal deterioration of the sulfonylimide aqueous solution caused by the thermal decomposition of the sulfonylimide compound (1), the heating temperature in the dehydration process is preferably a relatively low temperature. The heating temperature is preferably 10 to 110°C, more preferably 15 to 90°C, even more preferably 20 to 80°C, and particularly preferably 30 to 70°C.

[0093] The processing time in the dehydration process can be adjusted appropriately according to the pressure reduction, heating temperature, type and amount of electrolyte solvent added, etc., and there is no particular limitation. For example, it is preferred to be 0.1 to 24 hours, and more preferably 0.5 to 22 hours.

[0094] As a device used in the dehydration process to reduce pressure and / or heat, it can be appropriately selected based on factors such as the solution volume, degree of pressure reduction, and heating temperature. Examples include: trough reactors and depressurized trough reactors.

[0095] (Other processes)

[0096] Without prejudice to the purpose of this invention, the method for manufacturing the non-aqueous electrolyte may also include other steps. Examples of other steps include filtration, column purification, activated carbon treatment, and molecular sieve treatment.

[0097] (electrolytes)

[0098] The electrolyte only needs to contain the sulfonamide compound (1), but it may also contain other electrolytes (electrolytes other than the sulfonamide compound (1)). Other electrolytes may be mixed in a non-aqueous electrolyte or mixed in the sulfonamide aqueous solution during the above preparation process. Examples of other electrolytes include: imide salts, non-imide salts, etc.

[0099] As imide salts, examples include: other fluorinated sulfonyl imide salts (hereinafter referred to as "other sulfonyl imide compounds") that are different from sulfonyl imide compound (1). Examples of other sulfonyl imide compounds include: lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2, hereinafter also referred to as "LiTFSI"); lithium bis(pentafluoroethylsulfonyl)imide; lithium bis(heptafluoropropylsulfonyl)imide; non-lithium salts of fluorinated sulfonyl imides listed as sulfonyl imide compound (1) (e.g., salts obtained by replacing the lithium (ion) in sulfonyl imide compound (1) with cations other than lithium ions). Examples of salts in which lithium (ions) are replaced by cations other than lithium ions include: alkali metal salts such as sodium salts, potassium salts, rubidium salts, and cesium salts; alkaline earth metal salts such as beryllium salts, magnesium salts, calcium salts, strontium salts, and barium salts; aluminum salts; ammonium salts; phosphonium salts, etc. Other sulfonamide compounds can be used individually or in combination. These compounds can be commercially available or synthesized using existing, well-known methods.

[0100] As non-imide salts, examples that can be listed are salts composed of non-imide anions and cations (lithium ions and the cations in the examples above). Examples of non-imide salts include: fluorophosphates such as LiPF6, LiPF3(CF3)3, LiPF3(C2F5)3, LiPF3(C3F7)3, and LiPF3(C4F9)3; fluoroborates such as LiBF4, LiBF(CF3)3, LiBF(C2F5)3, and LiBF(C3F7)3; lithium salts such as lithium hexafluoroarsenate (LiAsF6), LiSbF6, LiClO4, LiSCN, LiAlF4, CF3SO3Li, LiC[(CF3SO2)3], LiN(NO2), and LiN[(CN)2]; and non-lithium salts (e.g., salts in which the lithium (ions) are replaced by the cations of the examples described above (e.g., NaBF4, NaPF6, NaPF3(CF3)3, etc.)). Non-imide salts can be used individually or in combination. In addition, non-imide salts can be commercially available products or compounds synthesized using existing known methods.

[0101] It should be noted that these electrolytes (sulfonamide compounds (1), other electrolytes, etc.) can also exist (contain) in non-aqueous electrolytes in ionic form.

[0102] From the viewpoint of improving storage stability, the concentration of the sulfonamide compound (1) in the non-aqueous electrolyte is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more. Furthermore, from the viewpoint of suppressing the decrease in battery performance caused by an increase in electrolyte viscosity, this concentration is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0103] (Electrolyte solvent)

[0104] The electrolyte solvent is not particularly limited as long as it can dissolve and disperse the electrolyte. Preferably, it is a non-aqueous solvent with a high dielectric constant, good solubility of the electrolyte salt, a boiling point above 60°C at normal pressure, and a wide electrochemical stability range. More preferably, it is an organic solvent with low water content. Examples of such organic solvents include: ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2,6-dimethyltetrahydrofuran, tetrahydropyran, crown ethers, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,4-dioxane, 1,3-dioxane, etc.; chain carbonate solvents such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), diphenyl carbonate, methyl phenyl carbonate, etc.; saturated cyclic carbonate solvents such as ethylene carbonate, propylene carbonate, 2,3-dimethylethylene carbonate, 1,2-butenyl carbonate, and erythritol carbonate; cyclic carbonate solvents with unsaturated bonds such as vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 2-ethylene ethylene carbonate, phenyl ethylene carbonate, etc.; fluoroethylene carbonate, 4,5-dioxane, etc. Fluorinated cyclic carbonate solvents such as fluoroethylene carbonate and propylene trifluorocarbonate; aromatic carboxylic acid ester solvents such as methyl benzoate and ethyl benzoate; lactone solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; phosphate ester solvents such as trimethyl phosphate, ethyl dimethyl phosphate, diethyl methyl phosphate, and triethyl phosphate; and nitrile solvents such as acetonitrile, propionitrile, methoxypropionitrile, glutaronitrile, adiponitrile, 2-methylglutaronitrile, valeronitrile, butyronitrile, and isobutyronitrile. Solvents include: sulfur compounds such as dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, sulfolane, 3-methylsulfolane, and 2,4-dimethylsulfolane; aromatic nitrile solvents such as benzonitrile and toluenenitrile; nitromethane, 1,3-dimethyl-2-imidazolinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, and 3-methyl-2-oxazolidinone; and chain ester solvents such as ethyl acetate and butyl acetate. These solvents can be used individually or in combination.

[0105] Among the electrolyte solvents, preferred solvents are carbonate solvents such as chain carbonates and cyclic carbonates, lactone solvents, ether solvents, and chain ester solvents. More preferred solvents are dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, γ-butyrolactone, and γ-valerolactone. Further preferred solvents are carbonate solvents such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate. Even more preferred solvents are chain carbonate solvents such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate.

[0106] (additive)

[0107] Non-aqueous electrolytes may also contain additives intended to improve various characteristics of lithium-ion secondary batteries. These additives can be added to the non-aqueous electrolyte or mixed into the sulfonylimide aqueous solution during the preparation process described above. As additives, the following can be listed: succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaric anhydride, itaconic anhydride, diethylene glycol anhydride, cyclohexane dicarboxylic anhydride, cyclopentane tetracarboxylic anhydride, phenyl succinic anhydride, and other carboxylic anhydrides; ethylene sulfite, 1,3-propane sulpholactone, 1,4-butane sulpholactone, methyl methanesulfonate, busulfan, sulfolane, sulfolane, dimethyl sulfone, tetramethylthiuram monosulfide, trimethylolpropanediol sulfate, and other sulfur-containing compounds; 1-methyl-2-pyrrolidone, 1-methyl-2-piperidinone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolinone, N-methylsuccinimide, and other nitrogen-containing compounds; heptane, octane, cycloheptane, and other saturated hydrocarbons. Hydrocarbon compounds; carbonate compounds such as vinylene carbonate, fluoroethylene carbonate (FEC), propylene trifluorocarbonate, styrene carbonate, and erythritol carbonate; aminosulfonic acids (amide sulfuric acid, H3NSO3); aminosulfonates (alkali metal salts such as lithium, sodium, and potassium salts; alkaline earth metal salts such as calcium, strontium, and barium salts; other metal salts such as manganese, copper, zinc, iron, cobalt, and nickel salts; ammonium salts; guanidine salts, etc.); fluorophosphate compounds such as lithium monofluorophosphate (Li2PO3F) and lithium difluorophosphate (LiPO2F2); lithium bis(oxalate)borate (LiBOB), lithium difluorooxalateborate (LiDFOB), and lithium difluorooxalate phosphate (LIDFOP). Lithium salts with an oxalate structure, such as lithium difluoro(oxalato)phosphate, lithium tetrafluorooxalatophosphate (LITFOP), lithium difluorobis(oxalato)phosphate (LiDFBOP), and lithium tri(oxalato)phosphate, are fluorooxalate compounds. Other additives can be used individually or in combination.

[0108] In 100% by mass of the non-aqueous electrolyte, the additive is preferably used in a range of 0.1% by mass or more and 10% by mass or less, more preferably in a range of 0.2% by mass or more and 8% by mass or less, and even more preferably in a range of 0.3% by mass or more and 5% by mass or less. When the amount of additive used is too small, it is sometimes difficult to obtain the effect brought about by the additive. On the other hand, even if a large amount of additive is used, it may be difficult to obtain an effect commensurate with the amount added, and the viscosity of the non-aqueous electrolyte increases, and the conductivity may decrease.

[0109] From the viewpoint of improving the storage stability of non-aqueous electrolytes, the concentration of FSO3Li in the non-aqueous electrolyte is preferably 100 ppm (0.01% by mass) or less, and more preferably 50 ppm (0.005% by mass) or less, relative to the electrolyte.

[0110] The non-aqueous electrolyte as described above can be used, for example, in: batteries (batteries with charging and discharging mechanisms), energy storage (electrochemical) devices (or materials constituting their ionic conductors), etc. Specifically, the electrolyte can be used as an electrolyte for constituting, for example, primary batteries, secondary batteries (e.g., lithium (ion) secondary batteries), fuel cells, electrolytic capacitors, electric double-layer capacitors, solar cells, electrochromic display elements, etc.

[0111] <Method for manufacturing electrolyte composition>

[0112] The method for manufacturing the electrolyte composition according to this embodiment is a method for manufacturing an electrolyte composition containing a sulfonylimide compound (1) as an electrolyte. This manufacturing method is based on using a non-aqueous electrolyte obtained by the above-described method for manufacturing a non-aqueous electrolyte, and includes a step of removing the electrolyte solvent from the non-aqueous electrolyte by distillation (the pulverization step described below). Furthermore, from the perspective of using the obtained non-aqueous electrolyte as a raw material, the above-described method for manufacturing a non-aqueous electrolyte can also be included in one step of the method for manufacturing the electrolyte composition. That is, the method for manufacturing the electrolyte composition can also be described as a manufacturing method including a dehydration step and a pulverization step, in which the above-described sulfonylimide aqueous solution is dehydrated to perform solvent replacement, replacing water with electrolyte solvent. Furthermore, from the perspective of using the purified sulfonylimide aqueous solution as a raw material for a non-aqueous electrolyte, the purification method of the above-described sulfonylimide aqueous solution can also be included in one step of the method for manufacturing the electrolyte composition. In other words, the method for manufacturing the electrolyte composition can also be described as a manufacturing method including a preparation step, a heating step, a dehydration step, and a powdering step, wherein an aqueous solution of sulfonylimide is prepared in the preparation step; and in the heating step, the aqueous solution of sulfonylimide obtained from the preparation step is subjected to heat treatment. All matters described in the above-described methods for purifying the aqueous solution of sulfonylimide and for manufacturing non-aqueous electrolytes also apply to the method for manufacturing the electrolyte composition.

[0113] (Powdering process)

[0114] The powdering process is a process in which the electrolyte solvent is removed from the non-aqueous electrolyte after the dehydration process by distillation to obtain an electrolyte composition. That is, the obtained electrolyte composition is a powder (solid). There are no particular limitations on the method of powdering the non-aqueous electrolyte. For example, in the case of hydrogen fluoride, a method in which the hydrogen fluoride is removed by distillation at a temperature above the melting point of the sulfonylimide compound (1), and then cooled to below the melting point for powdering; a method in which the sulfonylimide compound (1) is powdered at a temperature below the melting point, and then the hydrogen fluoride is further removed by distillation; a method combining the above methods, etc. In addition, the same method as the drying and powdering process described in International Publication No. 2011 / 149095 can also be used.

[0115] (Other processes)

[0116] Without prejudice to the purpose of this invention, the method for manufacturing the electrolyte composition may also include other steps. Examples of other steps include filtration, column purification, activated carbon treatment, and molecular sieve treatment.

[0117] From the viewpoint of improving the storage stability of the electrolyte composition, the concentration of FSO3Li in the electrolyte composition obtained by the powdering process is preferably 100 ppm (0.01% by mass) or less, and more preferably 50 ppm (0.005% by mass) or less, relative to the electrolyte.

[0118] <Effect>

[0119] The following effects can be obtained by the purification method of sulfonamide aqueous solution, the manufacturing method of non-aqueous electrolyte and the manufacturing method of electrolyte composition involved in this embodiment.

[0120] The purification method of sulfonylimide aqueous solution is a method of purifying sulfonylimide aqueous solution containing sulfonylimide compound (1). By heating the aqueous solution, the FSO3Li in the aqueous solution can be sufficiently reduced.

[0121] The method for manufacturing the non-aqueous electrolyte involves using the aforementioned sulfonylimide aqueous solution as a raw material. By adding an electrolyte solvent to the aqueous solution and dehydrating it, a high-purity non-aqueous electrolyte with significantly reduced impurities such as FSO3Li can be obtained. This non-aqueous electrolyte can inhibit the decomposition of the sulfonylimide compound (1) and suppress the deterioration of the non-aqueous electrolyte even when stored at high temperatures (e.g., 40°C) for a long period (e.g., 3–4 months). In other words, a non-aqueous electrolyte with excellent storage stability can be obtained.

[0122] The method for manufacturing the electrolyte composition involves using the aforementioned non-aqueous electrolyte to produce the electrolyte composition. By removing the electrolyte solvent from the non-aqueous electrolyte through distillation, a powder (solid) form of the electrolyte composition can be obtained. By pulverizing the non-aqueous electrolyte, storage stability is further improved, and product distribution becomes easier.

[0123] Example

[0124] The present disclosure will now be described based on embodiments. It should be noted that the present disclosure is not limited to the following embodiments, and modifications and alterations can be made to the following embodiments in accordance with the spirit of the present disclosure. Such modifications and alterations should not be excluded from the scope of the present disclosure.

[0125] <Example 1>

[0126] Add 50.5 g of an aqueous solution of LiFSI containing 50.0% by mass lithium bis(fluorosulfonyl)imide (LiFSI, Mw: 187.06) (LiFSI / H2O) to a flask containing a stir bar. Immerse the flask in an oil bath set to 60°C and heat it under normal pressure for 15 hours while stirring (the heating process is the same below) to obtain the aqueous solution of LiFSI.

[0127] <Example 2>

[0128] Add 50.58 g of a LiFSI aqueous solution (LiFSI / H2O) containing 50.0% by mass LiFSI and 0.24 g of lithium aminosulfonate (H2NSO3Li) to a flask containing a stir bar. Immerse the flask in an oil bath set to 90°C and heat under normal pressure for 9 hours while stirring to obtain the LiFSI aqueous solution.

[0129] <Example 3>

[0130] Add 50.56 g of a LiFSI aqueous solution (LiFSI / H2O) containing 50.0% by mass LiFSI, 0.12 g of H2NSO3Li, and 0.16 g of lithium carbonate (Li2CO3) to a 200 mL flask containing a stir bar. Immerse the flask in an oil bath set to 90 °C and heat under normal pressure with stirring for 9 hours to obtain the LiFSI aqueous solution.

[0131] <Example 4>

[0132] Add 50.21 g of a LiFSI aqueous solution (LiFSI / H2O) containing 70.0% by mass LiFSI to a 200 mL flask containing a stir bar. Immerse the flask in an oil bath set to 90 °C and heat under normal pressure for 9 hours while stirring to obtain the LiFSI aqueous solution.

[0133] <Example 5>

[0134] Add 22.73 g of a LiFSI aqueous solution (LiFSI / H2O) containing 70.0% by mass LiFSI and 25.17 g of dimethyl carbonate (DMC, Mw: 90.08) to a 200 mL flask containing a stir bar. Immerse the flask in an oil bath set to 90 °C and heat under normal pressure for 9 hours with stirring to obtain the LiFSI aqueous solution.

[0135] <Example 6>

[0136] Add 22.11 g of a LiFSI aqueous solution (LiFSI / H2O) containing 70.0% by mass LiFSI, 0.10 g of H2NSO3Li, and 24.32 g of ethyl methyl carbonate (EMC) to a 200 mL flask containing a stir bar. Immerse the flask in an oil bath set to 60 °C and heat under normal pressure for 15 hours with stirring to obtain the LiFSI aqueous solution.

[0137] <Example 7>

[0138] Add 50.26 g of a LiFSI aqueous solution (LiFSI / H2O) containing 50.0% by mass LiFSI and 16.43 g of DMC to a 200 mL flask containing a stir bar. Immerse the flask in an oil bath set to 70 °C and heat under reduced pressure of 15 kPa for 23 hours while stirring to obtain the LiFSI aqueous solution.

[0139] [Evaluation of LiFSI aqueous solution]

[0140] The amounts of each component added in each embodiment and the heating conditions for heating the prepared LiFSI aqueous solution are shown in Table 1. Additionally, the concentration of FSO3Li relative to the sulfonamide compound (LiFSI) in the LiFSI aqueous solution obtained in each embodiment before and after heating treatment was measured using the following method. The results are shown in Table 1. Figure 1 It should be noted that the "%" in the "LiFSI / H2O" column of Table 1 refers to "mass %". In addition, the reduction rate (%) of FSO3Li concentration in Table 1 is the value calculated according to the above formula (1).

[0141] [FSO3Li concentration]

[0142] The concentration of FSO3Li in LiFSI aqueous solutions was measured by ion chromatography. Specifically, each LiFSI aqueous solution was diluted 100-fold with ultrapure water (greater than 18.2 Ω·cm) to prepare the measurement solution. The concentration of FSO3Li contained in the LiFSI aqueous solutions was measured using an ion chromatography system ICS-3000 (manufactured by Nippon Dionex). The measurement conditions are as follows.

[0143] (Measurement conditions for ion chromatography)

[0144] • Separation mode: Ion exchange

[0145] • Eluent: 7-18 mM KOH aqueous solution

[0146] • Detector: Conductivity detector

[0147] • Chromatographic column: Ion PAC AS-17C column for anion analysis (manufactured by Nippon Dionex).

[0148] Table 1

[0149]

[0150] As shown in Table 1, in Examples 1-7, heat treatment significantly reduced the amount of FSO3Li in the LiFSI aqueous solution. Furthermore, it is evident that the reduction in FSO3Li was achieved regardless of whether an anionic component was added to the LiFSI aqueous solution. In other words, adding anionic components has little impact on the reduction effect of FSO3Li resulting from heat treatment.

[0151] according to Figure 1 The results show that when the heating temperature is 90℃, the concentration of FSO3Li is halved after about 2 hours, and decreases linearly until about 4 hours (the rate of decrease is fast).

[0152] <Example 8>

[0153] 38.51 g of DMC was added to the heat-treated LiFSI aqueous solution obtained in Example 3 to obtain an aqueous LiFSI solution for dehydration. Next, the aqueous LiFSI solution for dehydration was subjected to a dehydration treatment for 20 hours under reduced pressure conditions of 60°C and 8 kPa (the same dehydration step below), thereby obtaining a LiFSI / DMC solution (non-aqueous electrolyte) containing 39.6% by mass LiFSI. Through the dehydration treatment, the FSO3Li concentration was further reduced from 104.5 ppm by mass (the FSO3Li concentration in the LiFSI aqueous solution after the heating step and before the dehydration step below) to 40.4 ppm by mass (the FSO3Li concentration in the non-aqueous electrolyte after the dehydration step below).

[0154] <Example 9>

[0155] 60.11 g of EMC was added to the heat-treated LiFSI aqueous solution obtained in Example 3 to obtain an aqueous LiFSI solution for dehydration. Next, the aqueous LiFSI solution for dehydration was subjected to dehydration treatment for 15 hours under reduced pressure conditions of 60°C and 8 kPa, thereby obtaining a LiFSI / EMC solution (non-aqueous electrolyte) containing 29.6% by mass LiFSI. Through dehydration treatment, the FSO3Li concentration was further reduced from 104.5 ppm by mass to 84.5 ppm by mass.

[0156] [Evaluation of non-aqueous electrolytes]

[0157] The non-aqueous electrolytes obtained from each embodiment were stored at 40°C for the specified times shown in Table 2. The LiFSI concentration in each non-aqueous electrolyte before and after storage was measured using the following method, and the anionic impurities (F) relative to the sulfonylimide compound (LiFSI) in the non-aqueous electrolyte were measured in the same manner as described above. － SO4 2－ The concentrations of FSO3Li were determined. The results are shown in Table 2. It should be noted that "ND" in Table 2 refers to less than the detection limit.

[0158] [LiFSI concentration]

[0159] The LiFSI concentration in the LiFSI aqueous solution is determined by... 19 Measured by F-NMR. 19 F-NMR measurements were performed using a Varian Unity Plus-400 (internal standard: trifluorotoluene, total number of measurements: 64).

[0160] Table 2

[0161]

[0162] According to the results in Table 2, in each embodiment after dehydration treatment of the heated LiFSI aqueous solution (containing DMC or EMC), the concentration of FSO3Li in the non-aqueous electrolyte was less than 100 ppm by mass. The concentrations of various impurities in the non-aqueous electrolyte showed almost no increase before and after storage, and the LiFSI concentration remained unchanged. This confirms that by heating the LiFSI aqueous solution used as a raw material, the FSO3Li in the non-aqueous electrolyte of each embodiment was sufficiently reduced, thus inhibiting SO42- even during long-term storage of 2–4 months. 2－ The generation of impurities, as a result, inhibits the decomposition of LiFSI. In other words, it can be said that the non-aqueous electrolytes of each embodiment exhibit excellent long-term storage stability.

[0163] <Example 10>

[0164] 11.98 g of the LiFSI / DMC solution (non-aqueous electrolyte) containing 40% by mass LiFSI obtained in Example 8 was weighed and added together with 40.09 g of TCE (1,1,2,2-tetrachloroethane) into a round-bottom flask. The solution was heated in an oil bath at approximately 50°C and concentrated under reduced pressure using a rotary evaporator to distill off solvents such as DMC (powdering process, hereinafter the same). After crystallization, the pressure was restored to atmospheric pressure, and then 40.38 g of TCE was added, followed by another reduction in pressure and concentration. As a result, the solvent in the flask disappeared, yielding a white powder (electrolyte composition). Analysis of the obtained white powder showed that FSO3Li was below the detection limit.

[0165] <Example 11>

[0166] 16.84 g of the LiFSI / EMC solution (non-aqueous electrolyte) containing 30% by mass LiFSI obtained in Example 9 was weighed and added together with 40.36 g of DCB (1,2-dichlorobenzene) into a round-bottom flask. The solution was heated in an oil bath at approximately 50°C and concentrated under reduced pressure using a rotary evaporator to distill off solvents such as EMC. After crystallization, the pressure was restored to atmospheric pressure, and then 40.21 g of DCB was added, followed by another reduction in pressure and concentration. As a result, the solvent in the flask disappeared, yielding a white powder (electrolyte composition). Analysis of the obtained white powder showed that FSO3Li was below the detection limit.

[0167] -Industry Applicability-

[0168] In summary, this disclosure applies to aqueous solutions of sulfonylimide, non-aqueous electrolytes, and electrolyte compositions that can be used as raw materials for non-aqueous electrolytes, etc.

Claims

1. A method for purifying an aqueous solution of sulfonamide, characterized in that: The purification method for the sulfonamide aqueous solution includes a heating step, in which the sulfonamide aqueous solution containing a sulfonamide compound represented by general formula (1) is heated. The sulfonamide aqueous solution further contains FSO3Li, water, and anionic components. The anionic component comprises at least one selected from the group consisting of aminosulfonic acid, acetic acid, carbonic acid, and phosphoric acid. The heating process reduces the concentration of FSO3Li in the sulfonamide aqueous solution. LiN(RSO2)(FSO2) (1) Wherein, R represents a fluorine atom, an alkyl group having 1 to 6 carbon atoms, or a fluoroalkyl group having 1 to 6 carbon atoms.

2. The method for purifying the sulfonylimide aqueous solution according to claim 1, characterized in that: The heating process takes more than 3 hours and less than 24 hours.

3. The method for purifying the sulfonylimide aqueous solution according to claim 1, characterized in that: The reduction rate of FSO3Li concentration in the sulfonamide aqueous solution before and after the heating process, as calculated by the following formula (1), is more than 50%. [Formula 1] The decrease rate of FSO3Li concentration in sulfonamide aqueous solution before and after heat treatment = [{(FSO3Li concentration in sulfonamide aqueous solution before heat treatment) - (FSO3Li concentration in sulfonamide aqueous solution after heat treatment)} / (FSO3Li concentration in sulfonamide aqueous solution before heat treatment)] × 100 (1).

4. The method for purifying the sulfonylimide aqueous solution according to claim 1, characterized in that: As a sulfonamide compound represented by the general formula (1), it contains LiN(FSO2)2.

5. The method for purifying the sulfonylimide aqueous solution according to claim 1, characterized in that: The content of the sulfonamide compound represented by the general formula (1) in the aqueous sulfonamide solution is 40% by mass or more and 80% by mass or less.

6. The method for purifying the sulfonylimide aqueous solution according to claim 1, characterized in that: The heating process includes a step of preparing the sulfonamide aqueous solution. In the preparation process, a non-aqueous solvent is added to the aqueous solution of the sulfonamide.

7. The method for purifying the sulfonamide aqueous solution according to claim 6, characterized in that: The non-aqueous solvents include chain carbonate solvents.

8. The method for purifying the sulfonamide aqueous solution according to claim 1, characterized in that: The heating process includes a step of preparing the sulfonamide aqueous solution. In the preparation process, an anionic component is added to the aqueous solution of sulfonamide.

9. The method for purifying the sulfonamide aqueous solution according to claim 8, characterized in that: The anionic component includes aminosulfonic acid and carbonic acid.

10. The method for purifying the sulfonylimide aqueous solution according to claim 8, characterized in that: The anionic component includes an alkali metal salt of aminosulfonic acid.

11. The method for purifying the sulfonylimide aqueous solution according to claim 8, characterized in that: The amount of the anionic component added is more than 0.1% by mass and less than 1% by mass in 100% by mass of the sulfonamide aqueous solution.

12. The method for purifying the sulfonylimide aqueous solution according to claim 1, characterized in that: The heating process includes a step of preparing the sulfonamide aqueous solution. In the preparation process, an anionic component and a non-aqueous solvent are added to the aqueous solution of sulfonamide.

13. The method for purifying the sulfonylimide aqueous solution according to claim 12, characterized in that: The anionic component includes aminosulfonic acid, and the non-aqueous solvent includes chain carbonate solvents.

14. The method for purifying the sulfonamide aqueous solution according to claim 1, characterized in that: In the heating process, the heating treatment is carried out under conditions of 60°C or higher and 120°C or lower.

15. The method for purifying the sulfonamide aqueous solution according to claim 1 or 14, characterized in that: In the heating process, the heating treatment is carried out under conditions below 30 kPa.

16. The method for purifying the sulfonamide aqueous solution according to claim 1 or 14, characterized in that: The concentration of FSO3Li in the aqueous sulfonamide solution after the heating process is less than 1500 ppm by mass, relative to the sulfonamide compound represented by the general formula (1).

17. A method for manufacturing a non-aqueous electrolyte, comprising a sulfonylimide compound represented by the general formula (1) as an electrolyte and an electrolyte solvent, characterized in that: Add the electrolyte solvent to the aqueous solution of sulfonamide refined by the refining method according to any one of claims 1 to 16 and dehydrate it.

18. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: The amount of electrolyte solvent added is less than 10,000g relative to 100g of the sulfonylimide compound represented by the general formula (1).

19. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: The amount of electrolyte solvent added is 1 to 1000 parts by mass relative to 100 parts by mass of the sulfonylimide compound represented by the general formula (1).

20. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: Dehydration is carried out under reduced pressure of less than 100 kPa.

21. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: Dehydration is carried out at a heating temperature of 10~110℃.

22. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: The dehydration process takes 0.1 to 24 hours.

23. The method for manufacturing the non-aqueous electrolyte according to claim 17, characterized in that: The concentration of the sulfonamide compound represented by the general formula (1) in the non-aqueous electrolyte is 30% by mass or more and 70% by mass or less.

24. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: The electrolyte solvent is a carbonate solvent.

25. The method for manufacturing a non-aqueous electrolyte according to claim 17, characterized in that: The electrolyte solvent is a chain carbonate solvent.

26. The method for manufacturing a non-aqueous electrolyte according to claim 17 or 25, characterized in that: The concentration of FSO3Li in the non-aqueous electrolyte is less than 100 ppm by mass relative to the electrolyte.

27. A method for manufacturing an electrolyte composition, comprising manufacturing an electrolyte composition containing a sulfonylimide compound represented by said general formula (1) as an electrolyte, characterized in that: The method for manufacturing the electrolyte composition includes a step of removing the electrolyte solvent from the non-aqueous electrolyte obtained by the manufacturing method of any one of claims 17 to 26 by distillation. The concentration of FSO3Li in the electrolyte composition is less than 100 ppm by mass relative to the electrolyte.

28. The method for manufacturing the electrolyte composition according to claim 27, characterized in that: The electrolyte composition is a powder.

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