JP7042018B2 - Manufacturing method of electrolytic solution material - Google Patents

Description

The present invention relates to a method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent.

The bis (fluorosulfonyl) imide alkali metal salt is a compound useful in various applications such as being used as an electrolyte for a non-aqueous electrolyte solution, an additive to an electrolyte solution of a fuel cell, an antistatic agent, and the like. Particularly in recent years, alkali metal batteries, especially lithium ion secondary batteries, have high energy densities and are therefore used as power sources for mobile communication devices, portable information terminals, etc., and their markets are rapidly expanding with the spread of terminals. ing.

As a method for producing a bis (fluorosulfonyl) imide alkali metal salt, Patent Document 1 describes that equimolar bis (fluorosulfonyl) imide and lithium fluoride are reacted at 180 ° C. for 1 hour in an autoclave in the presence of hydrogen fluoride. It is described that the bis (fluorosulfonyl) imide lithium salt was obtained in a yield of 99% or more. However, it is difficult to handle because a large amount of highly corrosive hydrogen fluoride is used as a solvent, and it is necessary to remove hydrogen fluoride from the product used as a solvent, so there is room for improvement.

Patent Document 2 describes that a bis (fluorosulfonyl) imide lithium salt was obtained by reacting bis (fluorosulfonyl) imide with lithium carbonate in an acetonitrile solvent and evaporating the solvent to dryness.

Further, Patent Document 3 describes a method for producing an electrolytic solution material containing a specific fluorosulfonylimide salt, in which a solution containing an electrolytic solution solvent is depressurized and / or heated to volatilize the production solvent.

Publication No. CA2527802 Special Table 2015-536898 Gazette International Publication No. 2016/052752

However, looking at Production Example 1 of Patent Document 1, an aqueous solution is used for purifying the bis (fluorosulfonyl) imide alkali metal salt, and a non-aqueous electrolyte is obtained from the highly hygroscopic bis (fluorosulfonyl) imide alkali metal salt. In order to remove water in the case of production, it was necessary to go through a plurality of steps such as removing water by powdering and then preparing an electrolytic solution material containing a specific organic solvent.

The present invention has been made by paying attention to the above circumstances, and an object thereof is to use a bis (fluorosulfonyl) imide alkali metal salt preferably used for a non-aqueous electrolyte solution such as a lithium ion secondary battery. The present invention is to provide an electrolytic solution material containing an organic solvent.

The present invention is a method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent (A), in a reaction solution containing an organic solvent (B) different from the organic solvent (A). A method for producing an electrolytic solution material, which comprises a reaction between a bis (fluorosulfonyl) imide and an alkali metal compound, and a volatilization operation of the organic solvent (B) by depressurization and / or heating in the presence of the organic solvent (A). Is.

The organic solvent (A) is a carbonate solvent, a cyclic ether solvent, a chain ether solvent having 2 or more oxygen atoms in the molecule, a cyclic ester solvent, a sulfoxide solvent, N, N-dimethylformamide, and the like. It is preferably at least one selected from the group consisting of dimethyl sulfoxide and N-methyloxazolidinone.

The organic solvent (B) may be at least one selected from a group consisting of ketones, nitrile solvents, chain ester solvents and chain ether solvents having 1 oxygen atom in the molecule. preferable.

The molar ratio of the alkali metal contained in the alkali metal compound to the bis (fluorosulfonyl) imide is preferably 1.00 or more. When the molar ratio of the alkali metal compound to the bis (fluorosulfonyl) imide is 1.00 or more, the alkali metal compound insoluble in the organic solvent (A) or the organic solvent (B) can be removed by filtration. ..

The production method of the present invention preferably includes a purification step of filtering the electrolytic solution material.

The alkali metal compound is preferably LiCl and / or LiF. If the alkali metal compound is LiCl and / or LiF, the boiling point of HCl or HF, which is a by-product of the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound, is low, so that the bis (fluorosulfonyl) imide alkali Purification of the metal salt becomes easy, and lithium bis (fluorosulfonyl) imide suitable for an electrolytic solution for a lithium ion battery can be obtained.

According to the present invention, equipment for handling highly hygroscopic bis (fluorosulfonyl) imide alkali metal salt powder is not required, and the step of removing water from the bis (fluorosulfonyl) imide alkali metal salt is simplified. Therefore, the production cost can be reduced. Further, since the non-aqueous electrolytic solution can be obtained as it is or simply by diluting the electrolytic solution material of the present invention, workability is improved and the non-aqueous electrolytic solution can be produced inexpensively and easily.

Hereinafter, the present invention will be described in detail. Unless otherwise specified in the following description, "%" means "mass%", "part" means "parts by mass", and "A to B" indicating a range are A or more and B. It is shown that it is as follows.

The production method of the present invention is a method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent (A), and contains an organic solvent (B) different from the organic solvent (A). An electrolytic solution material comprising a reaction of a bis (fluorosulfonyl) imide with an alkali metal compound in a reaction solution and a volatilization operation of the organic solvent (B) by depressurization and / or heating in the presence of the organic solvent (A). It is a manufacturing method of.
[Reaction between bis (fluorosulfonyl) imide and alkali metal compound]
The reaction between the bis (fluorosulfonyl) imide (HFSI) and the alkali metal compound is carried out in a reaction solution containing an organic solvent (B).

Bis (fluorosulfonyl) imides can be synthesized by known methods. For example, a method of synthesizing a bis (fluorosulfonyl) imide from a bis (halide sulfonyl) imide using a fluorinating agent can be mentioned. Examples of the halogen in the bis (sulfonyl halide) imide include Cl, Br, I, and At other than F.

The fluorination step of synthesizing a bis (fluorosulfonyl) imide from a bis (sulfonyl halide) imide using a fluorinating agent will be described below. For example, a fluorination reaction of bis (sulfonyl halide) imide may be carried out. Specifically, the method described in CA2527802, Jean'ne m. Sheveve et al., Inorg. Chem. The method described in 1998, 37 (24), 6295-6303 and the like can be mentioned. Further, as the bis (sulfonyl halide) imide as a starting material, a commercially available product may be used, or a product synthesized by a known method may be used. Further, there is also a method for synthesizing a bis (fluorosulfonyl) imide using urea and fluorosulfonic acid, which is described in Japanese Patent Publication No. 8-511274.

Examples of the alkali metal compound in the production method of the present invention include hydroxides such as LiOH, NaOH, KOH, RbOH, and CsOH; Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ , Rb ₂ CO ₃ , and Cs ₂ . Carbonates such as CO ₃ ; hydrogen carbonates such as LiHCO 3, NaHCO 3, KHCO ₃ , RbHCO ₃ , CsHCO ₃ ; chlorides such as LiCl, NaCl, KCl, RbCl, CsCl; LiF, NaF, KF, RbF, CsF and the like. Alkali metal compounds such as fluoride; an alkoxide compound such as CH ₃ OLi, EtOLi; and an alkyl lithium compound such as EtLi, BuLi and t-BuLi (where Et is an ethyl group and Bu is a butyl group); Be done. Among them, alkali metal salts such as LiF, NaF, KF, LiCl, NaCl, and KCl are preferable, and LiCl and / or LiF are particularly preferable. If the alkali metal compound is LiCl and / or LiF, the boiling point of HCl or HF, which is a by-product of the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound, is low, so that the bis (fluorosulfonyl) imide alkali The purification of metal salts becomes easy.

The molar ratio of the alkali metal contained in the alkali metal compound to the bis (fluorosulfonyl) imide in the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound is preferably 1.00 or more. As the lower limit, 1.00 or more is more preferable, 1.01 or more is further preferable, 1.03 or more is further preferable, 1.05 or more is particularly preferable, and 1.10 or more is particularly preferable. The upper limit is more preferably 2.00 or less, further preferably 1.80 or less, further preferably 1.50 or less, particularly preferably 1.30 or less, and even more preferably 1.20 or less. If the molar ratio of the alkali metal contained in the alkali metal compound to bis (fluorosulfonyl) imide is in this range, an equal amount or more of the alkali metal compound will be used for the reaction, but the alkali metal compound is used in the electrolytic solution material. It is considered to be an insoluble solid, and the unreacted alkali metal compound can be purified by filtration. The bis (fluorosulfonyl) imide alkali metal salt is soluble in the electrolytic solution material. Further, since the bis (fluorosulfonyl) imide is not a solid but a liquid, it cannot be removed by filtration, but if the molar ratio of the alkali metal contained in the alkali metal compound to the bis (fluorosulfonyl) imide is within this range, the reaction conditions can be adjusted. If properly set, the amount of bis (fluorosulfonyl) imide contained after the reaction may be reduced, and the operation of removing the bis (fluorosulfonyl) imide after the reaction may be simplified.

The organic solvent (B) in the production method of the present invention may be different from the organic solvent (A), and is not particularly limited and may contain a known solvent. The organic solvent (B) is preferably used as a solvent for the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound and its purification. That is, it is a solvent preferably used for producing a bis (fluorosulfonyl) imide alkali metal salt, and may be hereinafter referred to as a production solvent in the present specification. Further, the organic solvent (B) may remain in the electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and the organic solvent (A), and may be hereinafter referred to as a residual solvent in the present application.

The organic solvent (B) is classified by the affinity with the bis (fluorosulfonyl) imide alkali metal salt, and the following can be mentioned. Solvents with moderate affinity for bis (fluorosulfonyl) imide alkali metal salts include water; alcohol solvents such as methanol, ethanol, propanol and butanol; carboxylic acid solvents such as formic acid and acetic acid; acetone, methyl ethyl ketone and methyl. Ketones such as isobutyl ketone and diisobutyl ketone; nitrile solvents such as isobutyronitrile, acetonitrile, valeronitrile and benzonitrile; chain ester solvents such as ethyl acetate, isopropyl acetate and butyl acetate; diethyl ether and diisopropyl ether, Chain ether solvents such as t-butylmethyl ether, cyclopentylmethyl ether, dimethoxymethane, 1,2-dimethoxyethane, etc., which have 1 oxygen atom in the molecule; tetrahydrofuran, 2-methyltetrachloride, 1,3-dioxane, Cyclic ether-based solvents such as 4-methyl-1,3-dioxolane; nitro group-containing solvents such as nitromethane and nitrobenzene; glime-based solvents and the like can be mentioned. Among them, acetonitrile, valeronitrile, ethyl acetate, isopropyl acetate, butyl acetate and cyclopentyl methyl ether are preferable. Solvents with low affinity for bis (fluorosulfonyl) imide alkali metal salts include toluene, o-xylene, m-xylene, p-xylene, benzene, ethylbenzene, isopropylbenzene, 1,2,3-trimethylbenzene, 1, Aromatic hydrocarbon solvents such as 2,4-trimethylbenzene, 1,3,5-trimethylbenzene, tetralin, xylene, methylethylbenzene, 2-ethyltoluene, chlorobenzene, dichlorobenzene (including halogenated hydrocarbons); pentane , Xylene, heptane, octane, decane, dodecane, undecane, tridecane, decalin, 2,2,4,6,6-pentamethylheptane, isoparaffin (eg, "Marcazole R" (2,2 manufactured by Maruzen Petrochemical Co., Ltd.) , 4,6,6-pentamethylheptane, 2,2,4,4,6-pentamethylheptane mixture), "Isoper® G" (C9-C11 mixed isoparaffin manufactured by Exxon Mobile), "Isoper" (Registered Trademark) E ”(C8-C10 mixed isoparaffin manufactured by Exxon Mobile) Chain aliphatic hydrocarbon solvent such as dichloromethane, chloroform, 1,2-dichloroethane (including halogenated hydrocarbon); cyclohexane, methylcyclohexane, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, ethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane, propylcyclohexane, butylcyclohexane, "Swa Cyclic aliphatic hydrocarbon solvent such as "Clean 150" (mixture of C9 alkylcyclohexane manufactured by Maruzen Petrochemical Co., Ltd.); Aromatic ether solvent such as anisole, 2-methylanisole, 3-methylanisole, 4-methylanisole. , Etc., These solvents may be used alone or in combination of two or more. Among them, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, isopropyl. Benzene, 1,2,4-trimethylbenzene, hexane, heptane, chlorobenzene, dichlorobenzene, dichloromethane, 1,2-dichloroethane are preferable. These solvents may be used alone or in combination of two or more. ..

Among them, as the organic solvent (B), at least one selected from a group consisting of ketones, nitrile solvents, chain ester solvents and chain ether solvents having 1 oxygen atom in the molecule. Is preferable. In particular, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, isobutyronitrile, acetonitrile, valeronitrile, benzonitrile, ethyl acetate, isopropyl acetate, butyl acetate, etc., diethyl ether, diisopropyl ether, t-butyl methyl ether, cyclopentylmethyl. It is preferably at least one selected from the group consisting of ether, dimethoxymethane and 1,2-dimethoxyethane.

The conditions for the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound performed in the reaction solution containing the organic solvent (B) are described below.

The reaction temperature in the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound can be 20 to 200 ° C. The upper limit is preferably 180 ° C. or lower, more preferably 160 ° C. or lower. The lower limit is preferably 40 ° C. or higher, more preferably 60 ° C. or higher. It is possible at 20-200 ° C. The upper limit is preferably 180 ° C. or lower, more preferably 160 ° C. or lower. The lower limit is preferably 40 ° C. or higher, more preferably 60 ° C. or higher.

The pressure in the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound may be under high pressure or normal pressure. The pressure range of the specific reaction is preferably 1250 hPa or less, more preferably 1150 hPa or less, still more preferably 1050 hPa or less.

The order of addition in the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound is not particularly limited, but the reaction is carried out while adding the alkali metal compound to the mixture of the organic solvent (B) and the bis (fluorosulfonyl) imide. Alternatively, the reaction may be carried out while adding bis (fluorosulfonyl) imide to the mixture of the organic solvent (B) and the alkali metal compound. Further, the reaction may be carried out while adding a mixture of the organic solvent (B) and the alkali metal compound to the mixture of the organic solvent (B) and the bis (fluorosulfonyl) imide, and the organic solvent (B) and the alkali metal compound may be reacted. The reaction may be carried out while adding a mixture of the organic solvent (B) and bis (fluorosulfonyl) imide to the mixture of. It is also possible to start the reaction after mixing the bis (fluorosulfonyl) imide, the alkali metal compound and the organic solvent (B). The addition method is not particularly limited, and examples thereof include a method of batch addition of a required amount, a batch addition method of dividing into several times, and a sequential addition method of continuous addition.

The method for producing an electrolytic solution material of the present invention preferably includes a purification step of filtering. As described above, the molar ratio of the alkali metal contained in the alkali metal compound to the bis (fluorosulfonyl) imide in the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound is preferably 1.00 or more. If the molar ratio of the alkali metal contained in the alkali metal compound to bis (fluorosulfonyl) imide is in this range, an equivalent amount or more of the alkali metal compound will be used for the reaction, but the alkali metal compound is insoluble in the reaction solution. The unreacted alkali metal compound can be purified by filtering the reaction solution. After the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound, it is preferable to purify the reaction solution by filtration. The purification step may include operations such as solid precipitation such as known crystallization, distillation, and concentration other than filtration.
[Operation of adding organic solvent (A)]
The method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent (A) of the present invention preferably includes an operation of adding the organic solvent (A). Since the electrolytic solution material of the present invention is used for a non-aqueous electrolytic solution such as a lithium secondary battery, the organic solvent (A) contained in the electrolytic solution material of the present invention should be a solvent that can be used as it is as the electrolytic solution material. In the present specification, the organic solvent (A) may be referred to as an electrolytic solution solvent.

The operation of adding the organic solvent (A) is possible even before the start of the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound described above. It can be carried out after the start of the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound, during the reaction, or after the end of the reaction, and may be carried out for a solution containing the bis (fluorosulfonyl) imide alkali metal salt. preferable. The method of adding the organic solvent (A) is not particularly limited, and examples thereof include a method of collectively adding the required amount of the organic solvent (A), a batch addition method of dividing into several times, and a sequential addition method of continuous addition. Be done.

In the method for producing an electrolytic solution material of the present invention, the amount of the organic solvent (A) added is not particularly limited at the lower limit, and may be appropriately adjusted depending on the amount of the residual solvent and the like. For example, with respect to 100 g of the bis (fluorosulfonyl) imide alkali metal salt, 10,000 g or less is preferable, more preferably 5000 g or less, still more preferably 1000 g or less, still more preferably 500 g or less, still more preferably 200 g or less, and most preferably 100 g. It is as follows.

In the method for producing an electrolytic solution material of the present invention, the amount of the organic solvent (A) added is, for example, preferably 1 to 10000 parts by mass, more preferably 1 part by mass with respect to 100 parts by mass of the bis (fluorosulfonyl) imide alkali metal salt. Is 5 to 5000 parts by mass, more preferably 10 to 1000 parts by mass, particularly preferably 30 to 500 parts by mass, and even more preferably 50 to 200 parts by mass.

The organic solvent (A) in the production method of the present invention has a high affinity with a bis (fluorosulfonyl) imide alkali metal salt, can be suitably used in a volatile step, and a solvent that can be used as it is as an electrolytic solution material is used. It is preferable to do so. Further, a solvent having low solubility of the alkali metal compound is preferable. If the affinity with the bis (fluorosulfonyl) imide alkali metal salt is high and the solubility of the alkali metal compound is low, as described above, the alkali metal contained in the electrolytic solution material containing the bis (fluorosulfonyl) imide alkali metal salt. The compound can be purified by filtration.

The organic solvent (A) in the production method of the present invention includes a carbonate solvent, a cyclic ether solvent, a chain ether solvent having 2 or more oxygen atoms in the molecule, a cyclic ester solvent, a sulfoxide solvent, and N. , N-Dimethylformamide, dimethyl sulfoxide and N-methyloxazolidinone, preferably at least one selected from the group.

The organic solvent (A) is a carbonate-based solvent such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate; the number of oxygen atoms in the molecule such as dimethoxymethane and 1,2-dimethoxyethane. A chain ether solvent having 2 or more; a cyclic ether solvent such as tetrahydrofuran, 2-methyltetrahexyl, 1,3-dioxane, 4-methyl-1,3-dioxolane; a cyclic ether such as γ-butyrolactone and γ-valerolactone. Ester-based solvents; sulforane-based solvents such as sulfolane and 3-methylsulfolane; N, N-dimethylformamide, dimethylsulfoxide, N-methyloxazolidinone and the like can be mentioned. These solvents may be used alone or in combination of two or more. Among the above-exemplified solvents, carbonate solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate (particularly cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate) and γ-butyrolactone , Γ-Valerolactone and other cyclic ester solvents are preferred.
[Volaration operation of organic solvent (B) by depressurization and / or heating]
The method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent (A) of the present invention is to volatilize the organic solvent (B) by reducing pressure and / or heating in the presence of the organic solvent (A). Including operations.

The volatilization operation of the organic solvent (B) by depressurization and / or heating is possible even before the start of the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound. It can be carried out after the start of the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound, during the reaction, or after the end of the reaction, and may be carried out for a solution containing the bis (fluorosulfonyl) imide alkali metal salt. preferable.

In the method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent (A) of the present invention, a solution containing a bis (fluorosulfonyl) imide alkali metal salt is depressurized in the presence of the organic solvent (A). And / or heat to volatilize the organic solvent (B). That is, it is preferable to start the volatilization operation of the organic solvent (B) by depressurizing and / or heating after the start of the operation of adding the organic solvent (A). The start of the volatilization operation of the organic solvent (B) by depressurizing and / or heating can be started even before the start of the operation of adding the organic solvent (A).

Even if the bis (fluorosulfonyl) imide alkali metal salt is isolated as a powder (solid), it is considered that the powder contains the organic solvent (B) used before the isolation, but the present invention If it is a production method, the content of the organic solvent (B) in the electrolytic solution material can be reduced. The organic solvent (A) in the present invention has a higher affinity with the bis (fluorosulfonyl) imide alkali metal salt than the organic solvent (B) which may be contained in the electrolytic solution material as a residual solvent, and has a volatile operation. A solvent that can be suitably used as an electrolytic solution material and can be used as it is can be used. By using such an organic solvent (A), the residual solvent can be efficiently removed. Furthermore, the electrolytic solution material of the present invention can be used as it is as an electrolytic solution for a lithium secondary battery by mixing necessary solvents, additives, electrolytes and the like.

In the method for producing an electrolytic solution material of the present invention, the amount of residual solvent contained before the volatilization operation is not particularly limited at the lower limit, but is, for example, 1000 g or less with respect to 100 g of the bis (fluorosulfonyl) imide alkali metal salt. Is preferable, more preferably 500 g or less, still more preferably 100 g or less, and most preferably 50 g or less. When the amount of residual solvent is large, the amount of the organic solvent (A) used increases and the time required for volatilization increases, which is not desirable. When a solution obtained by producing and purifying a bis (fluorosulfonyl) imide alkali metal salt in a solution is used for a volatilization operation, the solvent is distilled off before the volatilization operation (before adding the organic solvent (A)). It is preferable to reduce the amount of the residual solvent contained in the above-mentioned range and set the amount of the residual solvent in the above range.

The volatilization operation is not particularly limited and can be performed under normal pressure or reduced pressure. From the viewpoint of preventing the decomposition of the bis (fluorosulfonyl) imide alkali metal salt by heat, it is desirable to carry out under reduced pressure. The degree of reduced pressure may be appropriately adjusted according to the type of the residual solvent and the type of the organic solvent (A) and is not particularly limited, but is preferably 200 kPa or less, more preferably 40 kPa or less, and further preferably 40 kPa or less. It is 15 kPa or less, and particularly preferably 5 kPa or less.

The volatilization temperature may be appropriately adjusted according to the degree of reduced pressure, the type of residual solvent, and the type of the organic solvent (A), and is not particularly limited. It is desirable to carry out at a relatively low temperature. For example, it is preferably 10 to 110 ° C, more preferably 15 to 80 ° C, still more preferably 20 to 60 ° C, and particularly preferably 30 to 50 ° C.

The volatilization time may be appropriately adjusted according to the degree of decompression, heating temperature, amount of residual solvent, etc., and is not particularly limited, but is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours, for example. It is more preferably 1 to 8 hours, and particularly preferably 2 to 5 hours.

The device capable of depressurizing and / or heating used for the volatilization operation may be appropriately selected according to the amount of solution, the degree of decompression, the heating temperature, and the like. For example, a tank reactor, a tank reactor capable of depressurizing, and the like can be mentioned.
[Method for manufacturing electrolyte material containing bis (fluorosulfonyl) imide alkali metal salt]
Examples of the bis (fluorosulfonyl) imide alkali metal salt include lithium bis (fluorosulfonyl) imide (LiFSI), sodium bis (fluorosulfonyl) imide (NaFSI), potassium bis (fluorosulfonyl) imide alkali metal salt and the like. More preferably, it is a lithium bis (fluorosulfonyl) imide.

The concentration of the bis (fluorosulfonyl) imide alkali metal salt contained in the electrolytic solution material may be appropriately adjusted according to the type of the organic solvent (A) and is not particularly limited, but is preferably 15 to 95% by mass, for example. , More preferably 20 to 90% by mass, still more preferably 30 to 90% by mass. Bis (fluorosulfonyl) imide contained in the electrolytic solution material from the viewpoint that the concentration of the electrolyte salt in the non-aqueous electrolytic solution can be appropriately set when an organic solvent is added to the electrolytic solution material to produce a non-aqueous electrolytic solution. The concentration of the alkali metal salt is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more. The electrolyte material of the present invention has good stability because the concentration of the bis (fluorosulfonyl) imide alkali metal salt is 30% by mass or more, and HF (hydrogen fluoride) which causes corrosion of the container used for storage and transportation. Since the generation of acid) is suppressed, it is also suitable for storage and transportation of bis (fluorosulfonyl) imide alkali metal salts.

As the organic solvent (A) contained in the electrolytic solution material of the present invention, the above-mentioned organic solvent (A) can be used, but cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate, or γ-butyrolactone and γ- It is preferable to contain a cyclic ester solvent such as valerolactone. Among them, ethylene carbonate or γ-butyrolactone is preferably contained, and ethylene carbonate is particularly preferable. The above cyclic carbonate or cyclic ester solvent is preferably contained in an amount of 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, based on the total amount of the organic solvent (A).

The amount of the organic solvent (B) in the electrolytic solution material may be appropriately adjusted depending on the type of the concentration residual solvent of the electrolytic solution material and is not particularly limited, but is preferably 3000 ppm or less, more preferably 2000 ppm or less, for example. It is more preferably 1000 ppm or less, particularly preferably 500 ppm or less, and most preferably 200 ppm or less. When the residual amount of the organic solvent (B) of the bis (fluorosulfonyl) imide alkali metal salt contained in the electrolytic solution is within the above range, the amount of the solvent in the obtained non-aqueous electrolytic solution can be suppressed. In the battery using the non-aqueous electrolyte solution, the side reaction at the time of driving is suppressed, and the swelling of the battery can be suppressed.

After the volatilization operation is completed, known purification operations such as filtration, column purification, activated carbon treatment, molecular sieve treatment, solid precipitation such as crystallization, and concentration may be performed, if necessary.

The method for producing an electrolytic solution material of the present invention preferably includes a purification step of filtering. In particular, it is preferable to include a purification step of filtering the electrolytic solution material. As described above, the molar ratio of the alkali metal contained in the alkali metal compound to the bis (fluorosulfonyl) imide in the reaction between the bis (fluorosulfonyl) imide and the alkali metal compound is preferably 1.00 or more. If the molar ratio of the alkali metal contained in the alkali metal compound to bis (fluorosulfonyl) imide is in this range, an equal amount or more of the alkali metal compound will be used for the reaction, but the alkali metal compound is used in the electrolytic solution material. It is considered that it becomes an insoluble solid, and the unreacted alkali metal compound in the electrolytic solution material can be purified by filtration.

The electrolytic solution material obtained by the production method of the present invention includes a primary battery, a lithium ion secondary battery, a battery having a charging / discharging mechanism such as a fuel cell, an electrolytic capacitor, an electric double layer capacitor, a solar cell, an electrochemical display element, and the like. It is suitably used as a material for an ionic conductor constituting a power storage device (electrochemical device).

The present invention also includes a non-aqueous electrolytic solution obtained by using the above electrolytic solution material, and a method for producing a non-aqueous electrolytic solution using the above electrolytic solution material. A non-aqueous electrolytic solution can be obtained by mixing the above electrolytic solution material with a solvent for preparing a non-aqueous electrolytic solution, if necessary. Various electrolytes, additives, etc. may be added to the non-aqueous electrolyte solution for the purpose of improving battery characteristics, and a solvent suitable for dissolving the electrolyte, etc. may be added to the electrolyte solution material. In the present invention, the electrolyte solution material may be added. A non-aqueous electrolyte solution can be prepared by adding a desired solvent to the solution.

Therefore, the solvent for preparing the electrolytic solution is not particularly limited as long as it is compatible with the organic solvent (A) and can dissolve and disperse a desired electrolyte salt. Further, in the present invention, any conventionally known solvent used for a battery, such as a non-aqueous solvent, a polymer used in place of the solvent, and a medium such as a polymer gel, can be used. Although the electrolytic solution material contains an organic solvent (A), a solvent of the same type as the organic solvent (A) may be further added to the electrolytic solution material as needed, and the above-mentioned organic solvent (A) may be added. ) Can be used. The solvent for preparing the electrolytic solution may be either a liquid or a solid, but a liquid is preferable for efficient mixing. Further, the temperature of the solvent for preparing the electrolytic solution is not particularly limited, and may be room temperature, but the temperature may be appropriately adjusted as needed.

Among the solvents for preparing the electrolytic solution, carbonate esters (carbonate-based solvents) such as chain carbonate esters and cyclic carbonate esters, lactones, and ethers are preferable, and dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, and ethylene carbonate, are preferable. Peluccicarbonate, γ-butyrolactone, γ-valerolactone and the like are more preferable, and carbonate solvents such as dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, ethylene carbonate and propylene carbonate are even more preferable. The above solvent may be used alone or in combination of two or more.

In the present invention, if necessary, an electrolyte salt different from the bis (fluorosulfonyl) imide alkali metal salt (hereinafter, may be referred to as “another electrolyte salt”) may be mixed with the electrolyte solution material. Other electrolyte salts may be added to the electrolyte solution material before the electrolyte preparation solvent is added, but considering the dissolution efficiency of the other electrolyte salts, after the electrolyte preparation solvent is added to the electrolyte solution material, It is desirable to add other electrolyte salts. For example, when the other electrolyte salt to be added is sparingly soluble in ethylene carbonate such as LiPF ₆ , a solvent suitable for dissolving the electrolyte salt is added to the electrolyte solution material as the solvent for preparing the electrolyte, and then the electrolyte salt is added. It is desirable to add it.

The other electrolyte salt is not particularly limited, and any conventionally known electrolyte used in the electrolytic solution of the lithium ion secondary battery can be used. For example, other electrolyte salts include trifluoromethanesulfonic acid ion (CF ₃ SO _3- ⁾ , fluorophosphate ion (PF _6- ⁾ , perchlorate ion (ClO _4- ⁾ , tetrafluoroborate ion (BF _4- ⁾ . , Hexafluoroaricate ion (AsF _6- ), tetracyanoborate ion ([B (CN) ₄ ] ^- ), tetrachloroaluminum ion (AlCl _4- ⁾ , tricyanomethide ion (C [(CN) ₃ ] ^{- )} ), Disianamide ion (N [(CN) ₂ ] ^- ), Tris (trifluoromethanesulfonyl) methide ion (C [(CF ₃ SO ₂ ) ₃ ] ^- ), Hexafluoroantimonate ion (SbF _6- ⁾ and dicyanotri. Conventionally known electrolyte salts such as an inorganic or organic cationic salt having an azolate ion (DCTA) as an anion and a fluorosulfonylimide salt other than the bis (fluorosulfonyl) imide alkali metal salt can be used. More specifically, LiPF ₆ , LiPF ₃ (C ₂ F ₅ ) ₃ , LiBF ₄ , LiBF (CF ₃ ) ₃ can be mentioned, preferably LiPF ₆ and LiBF ₄ , and more preferably LiPF ₆ . By mixing the electrolytic solution material of the present invention with a solvent for preparing an electrolytic solution and other electrolyte salts to produce a non-aqueous electrolytic solution, heat generation when mixing the electrolyte salts can be suppressed, so that the non-aqueous electrolytic solution can be used. Decomposition can be suppressed and an electrolytic solution of good quality can be obtained.

The non-aqueous electrolytic solution according to the present invention may contain an additive for the purpose of improving various characteristics of the lithium ion secondary battery. The additive may be added at any stage in the manufacturing process of the non-aqueous electrolyte solution, and is not particularly limited. For example, the additive may be added after the addition of the above-mentioned electrolyte salt.

The present invention also includes a method for storing and transporting the electrolytic solution material of the present invention. The electrolyte material of the present invention has good stability and suppresses the generation of HF (hydrofluoric acid) that causes corrosion of containers used for storage and transportation. Therefore, storage of bis (fluorosulfonyl) imide alkali metal salt Also suitable for transportation. The concentration of the bis (fluorosulfonyl) imide alkali metal salt in the electrolytic solution material is, for example, 35% by mass, 40% by mass or more, and 50% by mass or more. Examples of the upper limit of the concentration include 95% by mass or less and 90% by mass or less.

The container used for storing and transporting the electrolytic solution material of the present invention is not particularly limited in the form such as the size and material of the container, and conventionally known findings can be appropriately referred to. A small storage container may be used to store a small amount of electrolyte material synthesized at the laboratory level. Further, in order to store a large amount of electrolytic solution material synthesized at the industrial level, a large storage container may be used.

As the material of the storage container, for example, a metal material such as stainless steel or Hastelloy, a fluororesin such as polytetrafluoroethylene (PTFE), or the like can be adopted. Above all, from the viewpoint of high pressure resistance, it is preferable that the container is made of stainless steel. Further, for the purpose of further improving the corrosion resistance of the storage container, it is preferable to coat the inner surface of the container made of the above-mentioned metal or the like with a resin. At this time, the resin used for coating is not particularly limited, and for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (tetrafluoroethylene / hexafluoropropylene copolymer). Examples thereof include fluororesins such as FEP) and olefin resins such as polypropylene. Above all, from the viewpoint of excellent effect of improving corrosion resistance, it is preferable to use PTFE for coating. Here, the coating thickness of the resin coating is not particularly limited, but is preferably 10 to 3000 μm, and more preferably 500 to 1000 μm. Further, it is preferable that the storage container can be sealed, and as a means for making the container sealable, for example, a form in which a valve is provided in a part of the container is exemplified.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples as well as the present invention, and appropriate changes are made to the extent that it can meet the purposes of the preceding and the following. Of course, it is also possible to carry out the above, and all of them are included in the technical scope of the present invention.

Example 1
In a PFA (fluororesin) reaction vessel, 1.43 g (55 mmol) of LiF and 20 g of acetonitrile were weighed. HFSI [bis (fluorosulfonyl) imide] 9.05 g (50 mmol) was added. The reaction solution was reacted at 25 ° C. for 5 hours. 10 g of ethylene carbonate was added to the reaction solution, concentrated under reduced pressure at 50 ° C., and acetonitrile was distilled off. The precipitate was removed by filtration to give 19.3 g of an ethylene carbonate solution containing 9.35 g of LiFSI [bis (fluorosulfonyl) imide lithium salt]. The LiFSI content was determined by F-NMR.

Comparative Example 1
In a PFA (fluororesin) reaction vessel, 1.34 g (55 mmol) of LiF and 20 g of acetonitrile were weighed. HFSI [bis (fluorosulfonyl) imide] 9.05 g (50 mmol) was added. The reaction solution was reacted at 25 ° C. for 5 hours. The reaction solution was centrifuged to remove the solid. The obtained solution was evaporated to dryness under reduced pressure at 50 ° C. to obtain 9.35 g of LiFSI [bis (fluorosulfonyl) imide lithium salt]. It was confirmed by gas chromatography that acetonitrile remained as an impurity in the product.

The electrolytic solution material obtained by the production method of the present invention includes a primary battery, a lithium ion secondary battery, a battery having a charging / discharging mechanism such as a fuel cell, an electrolytic capacitor, an electric double layer capacitor, a solar cell, an electrochemical display element, and the like. It is suitably used as a material for an ionic conductor constituting a power storage device (electrochemical device).

Claims (3)

A method for producing an electrolytic solution material containing a bis (fluorosulfonyl) imide alkali metal salt and an organic solvent (A).
A reaction step of reacting a bis (fluorosulfonyl) imide with an alkali metal compound in a reaction solution containing an organic solvent (B) different from the organic solvent (A).
A volatilization step of performing a volatilization operation of the organic solvent (B) by depressurizing and / or heating in the presence of the organic solvent (A).
Including a purification step of filtering the electrolytic solution material.
In the reaction step, the molar ratio of the alkali metal contained in the alkali metal compound to the bis (fluorosulfonyl) imide is 1.03 or more and 1.20 or less, and the alkali metal compound is LiCl and / or LiF. A method for manufacturing an electrolytic solution material. The organic solvent (A) is a carbonate solvent, a cyclic ether solvent, a chain ether solvent having 2 or more oxygen atoms in the molecule, a cyclic ester solvent, a sulfoxide solvent, N, N-dimethylformamide, dimethyl. The method for producing an electrolytic solution material according to claim 1, which is at least one selected from the group consisting of sulfoxide and N-methyloxazolidinone. The organic solvent (B) is at least one selected from a group consisting of ketones, nitrile solvents, chain ester solvents and chain ether solvents having 1 oxygen atom in the aliphatic molecule. The method for producing an electrolytic solution material according to claim 1 or 2.