KR20230055130A - Preparation Method of Bis(fluorosulfony)imide Alkali metal Salt in Ketone Solvent - Google Patents

Abstract

The present invention relates to a method for manufacturing lithium bis(fluorosulfonyl)imide among ketone solvents. According to the present invention, bis(fluorosulfonyl)imide (HFS I) and alkali metal fluoride or alkali metal chloride are reacted in a reaction solution including at least one solvent selected from ketone solvents. The present invention can reduce energy costs for solvent removal.

Description

Preparation Method of Bis(fluorosulfony)imide Alkali Metal Salt in Ketone Solvent {Preparation Method of Bis(fluorosulfony)imide Alkali Metal Salt in Ketone Solvent}

The present invention relates to a method for preparing bis(fluorosulfonyl)imide alkali metal salt in a ketone solvent.

In accordance with the popularization of mobile devices, the commercialization of electric vehicles, and the increase in demand for electric storage devices, secondary batteries with performance such as high power, high energy density, and high discharge voltage are being developed. In particular, since the lithium ion secondary battery has high energy density, it is used as a power source for mobile communication devices and a power source for portable information terminals, and its market is rapidly growing with the spread of terminals. Since such a lithium secondary battery operates at a high driving voltage, an aqueous electrolyte solution highly reactive with lithium cannot be used. Lithium batteries use a non-aqueous electrolyte, that is, an organic electrolyte.

A lithium secondary battery includes a negative electrode, a positive electrode, and a separator together with a non-aqueous electrolyte.

In secondary batteries, the non-aqueous electrolyte serves as a medium for the movement of lithium ions between the positive and negative electrodes and improves the thermal, electrical, and physical safety of the battery. It consists of additives. Additives are numerous and are related to the formation of solid electrolyte interphase (SEI). As the salt, LiPF ₆ is mainly used, but recently, the use of bis(fluorosulfonyl)imide alkali metal salt, which has excellent performance such as excellent low temperature, instantaneous high output, and low resistance value, is increasing, and its representative material is lithium bis(fluorosulfonyl)imide (LiFSI).

As a method for producing bis(fluorosulfonyl)imide alkali metal salt, in US Patent Publication No. 2011-0178306, by reacting bis(fluorosulfonyl)imide with lithium fluoride in an autoclave in the presence of hydrogen fluoride , that bis(fluorosulfonyl)imide lithium salt was obtained in a yield of 99% or more. However, this method has a disadvantage in that it is highly corrosive to the reaction vessel because hydrogen fluoride is used. Meanwhile, Registered Patent Publication No. 10-1345271 proposes a method for preparing bis(fluorosulfonyl)imide alkali metal salt by a cation exchange reaction by reacting ammonium bis(fluorosulfonyl)imide with an alkali metal salt in an organic solvent. However, this method has a problem in that a large amount of energy is required in the process of removing the organic solvent and various impurities are generated and remain.

Registered Patent Publication 10-1345271 US Patent Publication 2011-0178306

Accordingly, an object of the present invention is to prepare a bis(fluorosulfonyl)imide alkali metal salt and a bis(fluorosulfonyl)imide alkali metal salt and a solvent without using hydrogen fluoride and without solvent removal. It is to provide a manufacturing method that can be used as an electrolyte. In addition, it is to provide a method for preparing a secondary battery electrolyte without water absorption by blocking moisture with bis(fluorosulfonyl)imide alkali metal salt having deliquescent properties.

In order to achieve the above object, the present invention,

Bis (fluorosulfonyl) imide (HFSI) and alkali metal fluoride or alkali metal chloride are reacted in a reaction solution containing at least one solvent selected from ketone solvents. It provides a method for preparing phonyl) imide alkali metal salt (MFSI).

The present invention provides a method for producing bis(fluorosulfonyl)imide alkali metal salt, characterized in that there is no recovery step of the produced bis(fluorosulfonyl)imide alkali metal salt in a solid phase.

Preferably, the molar ratio of the alkali metal fluoride or alkali metal chloride to the bis(fluorosulfonyl)imide is greater than 1.00.

The production method of the present invention preferably includes a purification step of filtering the reaction solution after the reaction.

The manufacturing method of the present invention may include removing volatile substances in the reaction solution by reducing pressure and/or heating.

The present invention provides a composition for a non-aqueous electrolyte solution for a secondary battery comprising a bis(fluorosulfonyl)imide alkali metal salt and ketone solvents prepared by the production method of the present invention.

In the present invention, after obtaining a solution containing a bis(fluorosulfonyl)imide alkali metal salt and a ketone by the method for preparing bis(fluorosulfonyl)imide alkali metal salt, bis(fluorosulfonyl)imide alkali metal salt Characterized in that the composition for a non-aqueous electrolyte solution containing the bis(fluorosulfonyl)imide alkali metal salt and ketone solvents is used for preparing an electrolyte solution without going through the recovery and drying process of the alkali metal salt in a solid phase. Provided is a method for manufacturing a non-aqueous electrolyte for a secondary battery.

According to the present invention, since the process of removing the solvent is not included to obtain the bis(fluorosulfonyl)imide alkali metal salt as a solid after the reaction, the generation of by-products generated in the solvent removal process can be reduced, and the solvent removal can be reduced. It has the effect of reducing energy costs for

In addition, when storing and transporting bis(fluorosulfonyl)imide alkali metal salt having deliquescent properties in a solid state, there is no difficulty in thoroughly blocking moisture, and there is an advantage in that it can be stored stably for a long time.

In addition, since the bis(fluorosulfonyl)imide alkali metal salt obtained in the present invention is obtained in the form of a solution containing an organic solvent used in a non-aqueous electrolyte solution, a non-aqueous electrolyte solution can be obtained as it is or only after being diluted. It is possible to increase the efficiency of manufacturing a non-aqueous electrolyte solution.

In addition, bis(fluorosulfonyl)imide alkali metal salt is not recovered as a solid but used as a raw material for an electrolyte solution in the form of a solution, and the moisture at this time is less than 50 ppm, so when the electrolyte is prepared using it, the effect of extending the life of the battery there is

Hereinafter, the present invention will be described in detail. The terms or words used in this specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventors can properly define the concept of terms in order to best explain their invention. Based on the principle, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention.

The present invention reacts bis(fluorosulfonyl)imide (HFSI) with alkali metal fluoride or alkali metal chloride in a reaction solution containing at least one solvent selected from ketone solvents to obtain bis(fluorosulfonyl) A method for preparing an imide alkali metal salt (LiFSI) is provided.

the present invention

(a) reacting bis(fluorosulfonyl)imide with alkali metal fluoride or alkali metal chloride in at least one solvent selected from ketone solvents

(b) providing a method for preparing bis(fluorosulfonyl)imide alkali metal salt comprising the step of filtering the reaction solution of step (a) to obtain a filtrate.

The alkali metal (M) may be Li, Na, K or Cs, and is preferably Li.

The present invention provides a production method characterized in that there is no step of recovering the produced bis(fluorosulfonyl)imide alkali metal salt into a solid phase.

The ketone solvents of the present invention are used in the electrolyte solution without being removed after the manufacture of MFSI, and the water content is preferably 1,000 ppm or less, more preferably 500 ppm or less, and even more preferably 100 ppm to prevent battery performance deterioration below

Bis(fluorosulfonyl)imide may be commercially available or may be synthesized and used by a known method. For example, a method of synthesizing bis(fluorosulfonyl)imide from bis(chlorosulfonyl)imide using a fluorinating agent is exemplified. There is also a method of synthesizing bis(fluorosulfonyl)imide using urea and fluorosulfonic acid.

In the production of bis(fluorosulfonyl)imide alkali metal salt, the present invention reacts alkali metal fluoride or alkali metal chloride with bis(fluorosulfonyl)imide (HFSI) to obtain HF or HCl as a by-product. However, since HF or HCl has a low boiling point, it can be easily removed by volatilization, and as a result, a high-purity bis(fluorosulfonyl)imide alkali metal salt can be obtained.

In the reaction of bis(fluorosulfonyl)imide with LiF or HCl, the molar ratio of alkali metal fluoride or alkali metal chloride to bis(fluorosulfonyl)imide is greater than 1.0 to 2.0, preferably 1.05 to 1.8; More preferably, it is 1.1 to 1.7, and even more preferably, it is 1.2 to 1.6. When the molar ratio of alkali metal fluoride or alkali metal chloride to bis(fluorosulfonyl)imide is within this range, when an excessive amount of alkali metal fluoride or alkali metal chloride is used relative to bis(fluorosulfonyl)imide, residual after reaction Alkali metal fluoride or alkali metal chloride can be easily removed by filtration, while the possibility of unreacted bis(fluorosulfonyl)imide remaining in the resulting bis(fluorosulfonyl)imide alkali metal salt can be sufficiently low. there is. Accordingly, it is possible to prevent a phenomenon in which unreacted bis(fluorosulfonyl)imide remains and is included in the electrolyte solution to destroy a solid electrolyte interphase (SEI) film.

On the other hand, when the alkali metal fluoride or alkali metal chloride is used in a molar ratio of more than 2, it does not help to improve the reaction yield, but it takes time to remove the alkali metal fluoride or alkali metal chloride after the reaction and the manufacturing cost increases.

The solvent used in the preparation of the bis(fluorosulfonyl)imide alkali metal salt of the present invention includes at least one selected from ketone solvents.

The inventors of the present invention studied various solvents, including carbonate-based solvents and cyclic ether-based solvents, to find a method of storing MFSI in a solution containing MFSI and a reaction solvent without recovering it as a solid phase after preparing MFSI and using it as an electrolyte solution. . However, carbonate-based solvents, cyclic ether-based solvents, etc. have been found to have poor stability due to gas generation due to oxidation at high temperatures. In addition, the carbonate-based solvent has a water absorption property, and when it absorbs water, there is a problem of inducing the production of sulfamic acid by hydrolyzing MFSI, and it has been confirmed that the removal of HF is also disadvantageous.

On the other hand, when the ketone solvents of the present invention are used for the production of MFSI, it is possible to dissolve MFSI to proceed with the production reaction of MFSI, and it is also found that the stability of MFSI is high even when stored in a solution state, and the present invention has been completed.

The ketone solvents may be a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, R1 and R2 are each independently a C1-C6 aliphatic hydrocarbon, a C1-C6 aliphatic hydrocarbon in which hydrogen bonded to carbon is substituted by fluorine, or one or more carbons in the chain are an ether group, an ester group, or It is a C1-C6 aliphatic hydrocarbon that is substituted with a ketone group and the hydrogen bonded to carbon can be substituted with fluorine.

The aliphatic hydrocarbon may be a straight-chain or branched-chain saturated or unsaturated hydrocarbon.

In addition, R1 and R2 may be connected to each other to form a ring.

The ketone solvents of Chemical Formula 1 may preferably be at least one selected from the group consisting of compounds A below.

[Compound Logistics A]

The present invention can sufficiently dissolve bis(fluorosulfonyl)imide alkali metal salt produced by using ketone solvents as a reaction solvent, and it is easy to remove unreacted substances.

In the present invention, by using ketone solvents as a reaction solvent, it is possible to use the bis(fluorosulfonyl)imide alkali metal salt as an electrolyte without removing the reaction solvent after preparation. When the ketone solvents of the present invention are used as the electrolyte of a secondary battery, it can effectively stabilize both electrodes of the positive and negative electrodes, increase the electrochemical stability of the electrolyte, reduce consumption, and improve the efficiency of the lithium metal secondary battery. .

In addition, when preparing MFSI from alkali metal fluoride or alkali metal chloride and HFSI, the most important thing is the removal of water in the solvent. Ketone compounds have the characteristic of being azeotropic like water when distilled off, so water is removed together when the solvent is removed There is an advantage to being

In the production method of the present invention, the weight ratio of ketone solvents to bis(fluorosulfonyl)imide may be 3 to 20, preferably 3 to 15. When ketone solvents are used in the above content, HFSI used in the reaction is sufficiently dissolved and alkali metal fluoride or alkali metal chloride is dissolved enough to react to bis (fluorosulfonyl) imide alkali metal salt production reaction It can proceed sufficiently, and the MFSI produced thereafter can be sufficiently dissolved. In addition, since the ketone solvents can be used as solvents for secondary battery electrolytes, there is an advantage in that the products and solvents can be used as electrolytes for MFSI at appropriate concentrations without removing solvents after the reaction.

In the present invention, in addition to ketone solvents, carbonate solvents may be further included as reaction solvents. When a carbonate-based solvent is further included, the weight ratio of ketone solvents and carbonate solvents may be 1:0.1 to less than 1. When the carbonate-based solvent is added in the above amount, there is an advantage in that all of the low-cost characteristics of carbonate can be secured while maintaining the ability to reduce the moisture of ketones, remove HF, and inhibit the production of sulfamic acid.

The carbonate solvents may be chain carbonate or cyclic carbonate solvents. The cyclic carbonate solvent is preferably at least one selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, and the chain carbonate solvent is preferably at least one selected from the group consisting of dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate.

The reaction temperature between bis(fluorosulfonyl)imide and alkali metal fluoride or alkali metal chloride is 0°C to 200°C, more preferably 10°C to 100°C. When the reaction temperature is lower than 0 ° C., the reaction rate is lowered, and when the reaction temperature is higher than the above, there is a possibility that by-products are generated, which is not preferable. The time required for the reaction varies depending on the scale of the reaction, but is preferably 0.1 hour to 48 hours, more preferably 0.5 hour to 24 hours.

The reaction can be carried out under normal pressure, but when carried out under reduced pressure, by-product HF or HCl is removed and the target product is easily synthesized. The reaction pressure is not particularly limited, but is preferably from less than atmospheric pressure to 0.01 atm, more preferably from 0 to 100 deg.

The manufacturing method of the present invention may include removing volatile substances in the reaction solution by reducing pressure and/or heating. HF or HCl produced as a by-product in the present invention is a substance that exists as a gas at 19.5 ° C. or higher and can be removed by reducing pressure and heating.

In the present invention, nitrogen gas bubbling may be performed to smoothly remove HF or HCl generated during or after the reaction of bis(fluorosulfonyl)imide with alkali metal fluoride or alkali metal chloride. Bubbling of nitrogen gas may be performed until the pH of the gas discharged from the reaction solution becomes 6 to 8. More preferably, the nitrogen gas bubbling is stopped when the pH reaches 6.5 to 7.5, and more preferably, the nitrogen gas bubbling is stopped when the pH reaches 6.8 to 7.2. When nitrogen gas bubbling is performed in this way, the content of fluorine or chlorine anions in the final product can be greatly reduced. When nitrogen gas bubbling is performed after the reaction of bis(fluorosulfonyl)imide with alkali metal fluoride or alkali metal chloride, the reaction may be performed by heating to room temperature or a temperature of 70° C. or lower. In this case, HF or HCl removal can be performed efficiently.

In the production method of the present invention, a filtration process may be performed to remove unreacted materials after the reaction. In the present invention, coarse particles are first removed with a filter having a pore diameter of 4 μm or more, preferably a filter having a pore diameter of 4 to 10 μm, and then the filtrate is filtered with a pore diameter of 1 μm or less, preferably more than 0.5 and 1 μm or less. Fine particles can be efficiently removed by filtering with a filter. The filtration step may be performed under normal pressure, increased pressure, or reduced pressure, but the filtration time may be shortened when filtration is performed under reduced pressure at a pressure of 0.1 atm or less. It is also possible to proceed by pressurizing the reaction solution injection side and reducing pressure on the filtrate side.

The present invention can be further filtered with a filter having a pore diameter of 0.5 µm or less.

In the present invention, the ketone solution containing the produced bis(fluorosulfonyl)imide alkali metal salt can be directly used as an electrolyte without removing the solvent, and when fine particles remain in the reaction solution, they are dispersed in the electrolyte to reduce the turbidity of the electrolyte. As a result, it is preferable to perform the filtering process as described above because the lifespan may be shortened, such as a decrease in the possible number of charge/discharge cycles of the battery.

The present invention may include a step of partially removing the ketone-based solvent after the filtration process. That is, the present invention may include a step of removing some of the ketone-based solvent by heating to remove remaining HF or HCl and water. The ketone-based solvent of the present invention is azeotropic with water, so that when the solvent is removed by heating the reaction solution, moisture can be removed as well.

The step of removing some of the solvent may be a step of removing 10-50% by weight, preferably 10-30% by weight, based on the initial solvent content used in the reaction.

The present invention provides a method for producing bis(fluorosulfonyl)imide alkali metal salt, characterized in that there is no recovery step of the produced bis(fluorosulfonyl)imide alkali metal salt in a solid phase.

The present invention does not recover the generated bis(fluorosulfonyl)imide alkali metal salt in a solid state, so that the bis(fluorosulfonyl)imide alkali metal salt absorbs moisture during drying or the problem of unnecessary organic solvent residue. can solve

The present invention provides a composition for a non-aqueous electrolyte solution for a secondary battery comprising a bis(fluorosulfonyl)imide alkali metal salt and ketone solvents prepared by the production method of the present invention. In the composition for a non-aqueous electrolyte for a secondary battery including nitrile-ether solvents, bis(fluorosulfonyl)imide alkali metal salt may be included in an amount of 5 to 50% by mass.

The non-aqueous electrolyte composition may further include at least one solvent selected from carbonate-based solvents and ether-based solvents.

The carbonate solvents may be linear carbonate or cyclic carbonate solvents. The cyclic carbonate solvent is preferably at least one selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, and the chain carbonate solvent is at least one selected from the group consisting of dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate. desirable.

The ether solvent is preferably at least one selected from the group consisting of diethyl ether, diisopropyl ether, t-butyl methyl ether and cyclopentyl methyl ether.

In the present invention, after obtaining a solution containing a bis(fluorosulfonyl)imide alkali metal salt and a ketone by the method for preparing bis(fluorosulfonyl)imide alkali metal salt, bis(fluorosulfonyl)imide alkali metal salt Secondary battery, characterized in that the non-aqueous electrolyte composition containing the bis (fluorosulfonyl) imide alkali metal salt and ketone solvents is used for preparing the electrolyte without going through the recovery and drying process of the alkali metal salt A method for preparing an aqueous electrolyte solution is provided.

The bis(fluorosulfonyl)imide alkali metal salt is preferably lithium bis(fluorosulfonyl)imide.

Since the bis(fluorosulfonyl)imide alkali metal salt included in the composition of the present invention is prepared using ketone solvents that can be used in a non-aqueous electrolyte solution, it can be used directly as an electrolyte material without a solvent removal process. A non-aqueous electrolyte solution can be obtained by using the composition as it is or only by diluting it.

The electrolyte solution obtained by the manufacturing method of the present invention is a primary battery, a lithium ion secondary battery, a battery having a charge / discharge mechanism such as a fuel cell, an electrolytic capacitor, an electric double layer capacitor, a solar cell, and an energy storage device such as an electrochromic display device. It can be used as a material for the ion conductor constituting the.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, in describing the present invention, descriptions of already known conditions or configurations will be omitted to clarify the gist of the present invention.

Example 1

In a PFA (fluorine resin) reaction vessel equipped with an agitator, condenser, and thermometer, 28.6g (1.1mol) of LiF and 1.5Kg of 2-hexanone of Formula 2 as a solvent (weight ratio to HFSI: 8.3) at room temperature under a nitrogen atmosphere was put in. 181 g (1 mol) of HFSI [bis(fluorosulfonyl)imide was added. Thereafter, the reaction solution was stirred at 25°C and normal pressure for 5 hours to react. Thereafter, the pressure was reduced to 0.1 atm to remove residual HF for 1 hour, and the reaction solution was first filtered through a filter with a pore size of 5 μm, and then filtered through a filter with a pore size of 1 μm secondly to obtain lithium bis (fluorosulfonyl) A 2-hexanone solution of de was obtained. The content of LiFSI was calculated by F-NMR.

[Formula 2]

Example 2

　LiFSI was obtained in the same manner as in Example 1, except that 31.2 g (1.2 mol) of LiF was used and the solvent was 1.0 kg (weight ratio 5.5) of Formula 3. Table 1 shows the amount of LiFSI obtained and the amount of the solution after the reaction.

[Formula 3]

Example 3

　LiFSI was obtained in the same manner as in Example 1, except that the solvent was changed to 1.2 kg (weight ratio 6.6) of Formula 4. The content of obtained 　LiFSI is as shown in Table 1.

[Formula 4]

Example 4

LiFSI was obtained in the same manner as in Example 1, except that 31.2 g (1.2 mol) of LiF was used and the solvent was 2 kg (weight ratio 11) of Chemical Formula 5. The content of obtained 　LiFSI is as shown in Table 1.

[Formula 5]

Example 5

　LiFSI was obtained in the same manner as in Example 1, except that 31.2 g (1.2 mol) of LiF was used and the solvent was 2 kg (weight ratio 11) of Chemical Formula 6. The content of obtained 　LiFSI is as shown in Table 1.

[Formula 6]

Example 6

　LiFSI was obtained in the same manner as in Example 1, except that 31.2 g (1.2 mol) of LiF was used and the solvent was 2 kg (weight ratio 11) of Chemical Formula 7. The content of obtained 　LiFSI is as shown in Table 1.

[Formula 7]

Example 7

　LiFSI was obtained in the same manner as in Example 1, except that 31.2 g (1.2 mol) of LiF was used and the solvent was 2 kg (weight ratio 11) of Chemical Formula 8. The content of obtained 　LiFSI is as shown in Table 1.

[Formula 8]

Example 8.

31.2g (1.2mol) of LiF and 2Kg of 2-hexanone of Formula 2 (weight ratio 11 to HFSI) as a solvent and 31.2g (1.2mol) of LiF were added to a PFA (fluorine resin) reaction vessel equipped with an agitator, condenser, and thermometer at room temperature under a nitrogen atmosphere. put in. 181 g (1 mol) of HFSI [bis(fluorosulfonyl)imide was added. Thereafter, the reaction solution was stirred at 25°C and normal pressure for 5 hours to react. Thereafter, nitrogen gas bubbling was performed to remove residual HF. The pH of the gas blown away by nitrogen gas bubbling was checked using a pH paper every 5 minutes (initial pH about 3), and the nitrogen gas bubbling was stopped when the pH reached 7. Thereafter, the reaction solution was firstly filtered through a filter having a pore diameter of 5 μm, and thereafter filtered through a filter having a pore diameter of 1 μm secondly to obtain 1.69 kg of a 2-hexanone solution of lithium bis(fluorosulfonyl)imide. The content of LiFSI was calculated by F-NMR.

[Formula 2]

division reaction solvent solvent content LiF content LiFSI content amount of solution Example 1 Formula 2 1.5 kg (8.3 times) 1.1mol 185g 0.96kg Example 2 Formula 3 1 kg (5.5 times) 1.2mol 186g 0.68kg Example 3 formula 4 1.2 kg (6.6 times) 1.1mol 185g 0.78kg Example 4 Formula 5 2 kg (11 times) 1.2mol 183g 1.18kg Example 5 formula 6 2 kg (11 times) 1.2mol 183g 1.38kg Example 6 Formula 7 2 kg (11 times) 1.2mol 185g 1.58kg Example 7 Formula 8 2 kg (11 times) 1.2mol 183g 1.35kg Example 8 Formula 2 2 kg (11 times) 1.2mol 185g 1.12kg

Comparative Example 1

Example 1 was performed except that acetonitrile was used as the solvent. The obtained solution was evaporated to dryness under reduced pressure at 50°C and approximately 50 to 100 hPa for 1 hour to obtain 187 g of lithium bis(fluorosulfonyl)imide. It was confirmed by gas chromatography that acetonitrile remained in the product as an impurity.

Claims (9)

Bis (fluorosulfonyl) imide (HFSI) and alkali metal fluoride or alkali metal chloride are reacted in a reaction solution containing at least one solvent selected from ketone solvents. Method for producing phonyl) imide alkali metal salt. The method according to claim 1, wherein the molar ratio of the alkali metal fluoride or alkali metal chloride to the bis(fluorosulfonyl)imide (HFSI) is greater than 1.00. The bis(fluorosulfonyl)imide according to claim 1 or 2, comprising a purification step of filtering the reaction solution after the reaction of bis(fluorosulfonyl)imide (HFSI) with alkali metal fluoride or alkali metal chloride. Method for producing de alkali metal salt. The method for producing an alkali metal salt of bis(fluorosulfonyl)imide according to claim 1 or 2, characterized in that there is no step of recovering the produced lithium bis(fluorosulfonyl)imide into a solid phase. The method for preparing bis(fluorosulfonyl)imide alkali metal salt according to claim 1 or claim 2, wherein the ketone solvents are compounds having a structure represented by Formula 1 below.
[Formula 1]

In Formula 1, R ₁ and R ₂ are each independently a C1-C6 aliphatic hydrocarbon, a C1-C6 aliphatic hydrocarbon in which hydrogen bonded to carbon is substituted by fluorine, or one or more carbons in the chain are an ether group or an ester It is a C1-C6 aliphatic hydrocarbon substituted with a group or a ketone group, and the hydrogen bonded to carbon may be substituted by fluorine,
The aliphatic hydrocarbon may be a straight-chain or branched-chain saturated or unsaturated hydrocarbon,
The R ₁ and R ₂ may be connected to each other to form a ring. The method for preparing bis(fluorosulfonyl)imide alkali metal salt according to claim 5, wherein the compound of Formula 1 is at least one compound selected from the following compounds A.
[Compound Logistics A]

The method according to claim 1, further comprising a carbonate-based solvent bis (fluorosulfonyl) imide alkali metal salt production method. A composition for a non-aqueous electrolyte solution for a secondary battery comprising a bis(fluorosulfonyl)imide alkali metal salt prepared by the method of claim 1 and ketone solvents. A method for preparing a non-aqueous electrolyte for a secondary battery, characterized in that the composition for a non-aqueous electrolyte for a secondary battery according to claim 8 is used for preparation of the electrolyte.