Method for producing a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide

Abstract

The present invention relates to a method for producing a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, and more particularly to a method for producing alkali metal or alkaline earth metal bis(fluorosulfonyl)imide with a carbonate and a solvent other than the carbonate, and then removing the solvent other than the carbonate to obtain a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide.

Description

Technical Field

[0001] The present invention relates to a method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, which comprises producing an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide with a carbonate and an organic solvent other than the carbonate, and then removing the organic solvent other than the carbonate to obtain a carbonate solution of the alkali metal or alkaline earth metal bis(fluorosulfonyl)imide.

Background Art

[0002] In recent years, with the development of the advanced electronic industry, the demand for portable electronic devices, electric vehicles, and electric storage devices used therein has been increasing, and the need for secondary batteries having a high energy density has been growing.

[0003] Among such secondary batteries, lithium secondary batteries are rechargeable and have an energy density per unit weight that is more than three times higher than that of conventional lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc., and can be rapidly charged. Therefore, they are widely used as driving power sources for portable electronic devices such as video cameras, mobile phones, notebook computers, and electric vehicles.

[0004] Along with this, the importance of lithium salts among the electrolyte components compatible with lithium secondary batteries has increased. In particular, lithium bis(fluorosulfonyl)imide compounds are expected to be applied in the fields of lithium secondary batteries and capacitors because they exhibit excellent thermal stability, chemical stability, and excellent lithium ion conductivity compared to LiPF6.

[0005] On the other hand, in order to obtain alkali metal or alkaline earth metal bis(fluorosulfonyl)imide in solid phase and use it as an electrolyte in a battery, and to obtain the aforementioned thermal stability, high ionic conductivity, and low corrosivity, it is necessary that the solid phase alkali metal or alkaline earth metal bis(fluorosulfonyl)imide is free from moisture and residual solvents. In the production of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, moisture and residual solvents interfere with the crystallization of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, especially lithium bis(fluorosulfonyl)imide, making production impossible. Even if crystallization occurs, residual moisture and residual solvents reduce the efficiency of the battery. Furthermore, when alkali metal or alkaline earth metal bis(fluorosulfonyl)imide obtained in solid phase is exposed to air, it may absorb water and dissolve (deliquescent). Therefore, there are attempts to produce lithium bis(fluorosulfonyl)imide in a solution phase rather than a solid phase. U.S. Patent Application Publication No. 2016-0149262 describes an attempt to produce lithium bis(fluorosulfonyl)imide by reacting bis(fluorosulfonyl)imide with a lithium compound in a carbonate-based solvent and then using this directly as an electrolyte. [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the aforementioned method does not mention the removal of moisture from the manufactured lithium bis(fluorosulfonyl)imide. A high moisture content in lithium bis(fluorosulfonyl)imide can cause battery corrosion and degrade battery performance, making it unsuitable for direct use in electrolytes. Therefore, there is still a need for a method to produce alkali metal or alkaline earth metal bis(fluorosulfonyl)imide solutions with higher purity (lower moisture content).

[0007] Therefore, the present invention aims to provide a method for producing a higher-purity alkali metal or alkaline earth metal bis(fluorosulfonyl)imide solution and a method for using it as an electrolyte in a secondary battery. [Means for solving the problem]

[0008] To achieve the above objective, the present invention, 1) Add ammonium bis(fluorosulfonyl)imide and an alkali metal salt or alkaline earth metal salt to a reactor under a nitrogen atmosphere, add carbonate and an organic solvent other than carbonate, and stir at room temperature for 1 to 7 hours, and The present invention provides a method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, comprising the steps of: 2) filtering the reaction solution from step 1) and concentrating it under reduced pressure at 30-90°C to remove organic solvents other than the carbonate.

[0009] Furthermore, the present invention, a) In the first reactor, a step of reacting chlorosulfonyl isocyanate and chlorosulfonic acid under a nitrogen atmosphere to produce bis(chlorosulfonyl)imide. b) In the second reactor, under a nitrogen atmosphere, NH4F and organic solvent are added, and then bis(chlorosulfonyl)imide from the first reactor is added dropwise at 10-30°C. c) After the dropwise addition is complete, the reaction is carried out at 50-90°C for 1-10 hours to produce ammonium bis(fluorosulfonyl)imide. d) The reaction solution from step c) is filtered, concentrated under reduced pressure, and then a sparingly soluble organic solvent is added to the ammonium bis(fluorosulfonyl)imide to obtain the ammonium bis(fluorosulfonyl)imide solid phase. e) Adding ammonium bis(fluorosulfonyl)imide, alkali metal salt or alkaline earth metal salt to the third reactor under a nitrogen atmosphere, adding carbonate and organic solvents other than carbonate, and stirring at room temperature for 1 to 7 hours, and The present invention provides a method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, comprising the steps of f) filtering the reaction solution from step e) and concentrating it under reduced pressure at 30-90°C to remove organic solvents other than the carbonate. [Effects of the Invention]

[0010] The present invention provides the effect of obtaining a carbonate solution containing high-purity alkali metal or alkaline earth metal bis(fluorosulfonyl)imide in high yield by reacting ammonium bis(fluorosulfonyl)imide with an alkali metal salt or alkaline earth metal salt with a carbonate and an organic solvent other than the carbonate to obtain a solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, and then removing the organic solvent other than the carbonate.

[0011] Furthermore, the present invention provides the advantage of being able to obtain alkali metal or alkaline earth metal bis(fluorosulfonyl)imide in high yield even in small quantities by solubilizing reactants and reagents using an organic solvent other than carbonate, such as an alcohol-based, ether-based, ester-based, ketone-based, or amine-based solvent that can hydrogenate with water, and furthermore, by forming an azeotrope with water, thereby allowing water to be removed relatively easily.

[0012] The present invention allows the use of a carbonate solution containing the high-purity alkali metal or alkaline earth metal bis(fluorosulfonyl)imide as an electrolyte, either as is or by adding one or more solvents, electrolyte salts, and additives selected from the group, thereby providing a high-purity electrolyte and an electrolyte containing an electrolyte salt that does not have the problem of deliquescence of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide. [Modes for carrying out the invention]

[0013] The present invention will now be described in detail. Notwithstanding the foregoing, terms or words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical spirit of the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0014] The present invention 1) Add ammonium bis(fluorosulfonyl)imide (NH4FSI) and an alkali metal salt or alkaline earth metal salt to a reactor under a nitrogen atmosphere, add carbonate and an organic solvent other than carbonate, and stir at room temperature for 1 to 7 hours, and The present invention provides a method for producing a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide (MFSI), comprising the steps of: 2) filtering the reaction solution from step 1) and concentrating it under reduced pressure at 30-90°C to remove organic solvents other than the carbonate.

[0015] The inventors, having made every effort to obtain a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide (MFSI), have confirmed that when producing MFSI (where M is an alkali metal or alkaline earth metal) by reacting NH4FSI with an alkali metal salt or alkaline earth metal salt, a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide (MFSI) can be obtained by mixing an organic solvent other than carbonate with the carbonate solvent and then removing the organic solvent other than carbonate, thereby completing the present invention.

[0016] The organic solvent other than the carbonate is an organic solvent that can readily dissolve ammonium bis(fluorosulfonyl)imide and alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, and has a lower boiling point than the carbonate solvent used in conjunction with it. Preferably, it is an organic solvent with a boiling point lower than 130°C.

[0017] In one embodiment, the organic solvent other than the carbonate is a solvent capable of hydrogen bonding with water. In this case, when it is removed after the MFSI production reaction, if water is present, there is an advantage that water can be removed by azeotropic distillation. The organic solvent other than the carbonate may preferably be an alcohol-based, ether-based, ester-based, ketone-based, or amine-based solvent, and more preferably, methanol, ethanol, isopropanol, propanol, acetone, dimethyl ether, diethyl ether, isopropyl ether, ethyl acetate, butyl acetate, and the like.

[0018] The present invention obtains a carbonate solution of MFSI by removing the organic solvent other than the carbonate after the production of MFSI, and the organic solvent other than the carbonate is removed by vacuum distillation after the reaction. The vacuum distillation can be carried out at a temperature of 30 to 90 °C, preferably 40 to 80 °C, under a pressure of 0.01 Torr to 10 Torr. At this time, when water is present as a by-product, the pressure and temperature at which water can be azeotropically distilled are preferred.

[0019] As a result of performing the vacuum distillation, the organic solvent other than the carbonate may remain in the carbonate solution of MFSI in a range of 500 ppm by weight or less, preferably 300 ppm by weight or less, and more preferably 0 to 200 ppm by weight or less. When the organic solvent other than the carbonate remains in the carbonate solution of MFSI within the above range, it is possible to prevent a decrease in battery performance when used in a secondary battery electrolyte.

[0020] The carbonate solvent of the present invention may be a chain or linear carbonate. As an example of the carbonate of the present invention, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and the like can be mentioned.

[0021] The carbonate and the organic solvent other than carbonate of the present invention can be used in an amount of 50 to 95% by weight of carbonate and 5 to 50% by weight of the organic solvent other than carbonate, preferably 60 to 90% by weight of carbonate and 10 to 40% by weight of the organic solvent other than carbonate, more preferably 70 to 85% by weight of carbonate and 15 to 30% by weight of the organic solvent other than carbonate. When the carbonate and the organic solvent other than carbonate are used in the above contents, ammonium bis(fluorosulfonyl)imide and an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide can be dissolved well, and the alkali metal or alkaline earth metal bis(fluorosulfonyl)imide can be produced with high purity. Then, the organic metal other than carbonate can be removed to obtain a high-purity carbonate solution.

[0022] In the present invention, the reaction of NH4FSI with an alkali metal salt or an alkaline earth metal salt can be carried out by reacting 1 mol or more of the alkali metal salt or alkaline earth metal salt, preferably more than 1 mol to 2 mol, more preferably 1.1 mol to 2 mol, with respect to 1 mol of NH4FSI. When the alkali metal salt or alkaline earth metal salt is used in an equimolar or excess amount with respect to NH4FSI, it is easy to remove the remaining alkali metal salt or alkaline earth metal salt that does not react by filtration, so that a high-purity alkali metal or alkaline earth metal bis(fluorosulfonyl)imide solution can be obtained.

[0023] The alkali metal of the alkali metal salt or alkaline earth metal salt of the present invention can be Li, Na, K, Rb or Cs, preferably Li or Cs. The alkaline earth metal can be Be, Mg, Ca, Sr, Ba or Ra, preferably Mg or Ca.

[0024] The alkali metal salt or alkaline earth metal salt of the present invention includes a halogen salt, a hydroxide salt, a carbonate salt, a hydrogen carbonate salt (HCO3 salt), an acetate salt, etc. of an alkali metal or alkaline earth metal.

[0025] In the production of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide carbonate solutions of the present invention, the carbonate solvent and non-carbonate solvents may be used in a weight ratio of 1 to 5 times, preferably 1 to 4 times, and more preferably 1 to 3 times, relative to NH4FSI in order to ensure a sufficient reaction. If the solvent is used in a weight ratio of less than 1 time relative to NH4FSI, the reaction will not proceed at a sufficient rate, and if it is used in a weight ratio exceeding 5 times, there is a disadvantage that the excess solvent must be removed before it can be used as an electrolyte.

[0026] The reaction of ammonium bis(fluorosulfonyl)imide (NH4FSI) with an alkali metal salt or alkaline earth metal salt may be carried out at room temperature under a nitrogen atmosphere and may be carried out for 1 to 7 hours.

[0027] After the reaction is complete, and before removing organic solvents other than carbonate by vacuum distillation, the reaction solution is filtered through a filter cloth with a pore size of 0.5 to 1.5 μm to remove residual alkali metal salts or alkaline earth metal salts.

[0028] The present invention provides a carbonate solution of MFSI after filtering and vacuum distillation of the reaction solution. The carbonate solution of MFSI may preferably contain 10-50% by weight of MFSI and 50-90% by weight of the carbonate solvent, and more preferably 20-40% by weight of MFSI and 60-80% by weight of the carbonate solvent. If the MFSI carbonate solution contains MFSI in the above amounts, it may be used as an electrolyte as is. The carbonate solvent may be added to produce a solution with an appropriate MFSI concentration.

[0029] Furthermore, the present invention, a) In the first reactor, a step of reacting chlorosulfonyl isocyanate and chlorosulfonic acid under a nitrogen atmosphere to produce bis(chlorosulfonyl)imide. b) In the second reactor, under a nitrogen atmosphere, NH4F and organic solvent are added, and then bis(chlorosulfonyl)imide from the first reactor is added dropwise at 10-30°C. c) After the dropwise addition is complete, the reaction is carried out at 50-90°C for 1-10 hours to produce ammonium bis(fluorosulfonyl)imide. d) The reaction solution from step c) is filtered, concentrated under reduced pressure, and then a poorly soluble organic solvent is added to obtain the solid phase of ammonium bis(fluorosulfonyl)imide. e) Adding ammonium bis(fluorosulfonyl)imide, alkali metal salt or alkaline earth metal salt to the third reactor under a nitrogen atmosphere, adding carbonate and organic solvents other than carbonate, and stirring at room temperature for 1 to 7 hours, and The present invention provides a method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide, comprising the steps of f) filtering the reaction solution from step e) and concentrating it under reduced pressure at 30-90°C to remove organic solvents other than the carbonate.

[0030] In other words, the present invention relates to the ammonium bis(fluorosulfonyl)imide, a) In the first reactor, a step of reacting chlorosulfonyl isocyanate and chlorosulfonic acid under a nitrogen atmosphere to produce bis(chlorosulfonyl)imide. b) In the second reactor, under a nitrogen atmosphere, NH4F and organic solvent are added, and then bis(chlorosulfonyl)imide from the first reactor is added dropwise at 15-20°C. c) After the dropwise addition is complete, the reaction is carried out at 50-90°C for 1-10 hours to produce ammonium bis(fluorosulfonyl)imide, and d) The reaction solution from step c) is filtered, concentrated under reduced pressure, and then an organic solvent that is poorly soluble in ammonium bis(fluorosulfonyl)imide is added to obtain an ammonium bis(fluorosulfonyl)imide solid phase.

[0031] To explain each step in detail, in step a), the molar ratio of chlorosulfonic acid to 1 mole of chlorosulfonyl isocyanate is greater than 1, preferably 1.01 to 1.1 moles. When the molar ratio of chlorosulfonic acid to 1 mole of chlorosulfonyl isocyanate is greater than 1 mole as described above, bis(chlorosulfonyl)imide can be produced in sufficient yield. The reaction can be carried out under a nitrogen gas atmosphere, after raising the temperature to 90 to 130°C, and then slowly stirring while maintaining this temperature for 10 to 30 hours. After the reaction is complete, the temperature of the reaction solution is lowered to 50°C or below.

[0032] In step b), the bis(chlorosulfonyl)imide produced in step a) is added dropwise to a reactor containing NH4F and an organic solvent, and heated to produce ammonium bis(fluorosulfonyl)imide. The molar ratio of HCSI to ammonium fluoride can be 2 to 6 moles of NH4F per 1 mole of HCSI, preferably 2.5 to 5.5 moles, and more preferably 3 to 5 moles. When NH4F is used in the above proportions relative to HCSI, the HCSI is sufficiently converted to NH4FSI, while the unreacted NH4F and by-product NH4Cl can be easily removed by filtration.

[0033] The organic solvent can be any polar aprotic solvent without limitation, preferably butyl acetate, acetonitrile, or dimethyl carbonate. The organic solvent can be used in a weight ratio of 2 to 8 times, preferably 3 to 7 times, and more preferably 3.5 to 6 times, relative to the HCSI. If the solvent is used in a weight ratio of less than 2 times the HCSI, the reaction will not proceed at a sufficient rate, and if it is used in a weight ratio greater than 8 times, there is no benefit in accelerating the reaction, but there is a disadvantage that the excess solvent must be removed in the subsequent vacuum concentration step.

[0034] After the HCSI has been added dropwise, the mixture is heated to 50-90°C under a nitrogen gas atmosphere, and the reaction is carried out for 1-10 hours while slowly stirring and maintaining this temperature to produce NH4FSI.

[0035] Once the NH4FSI production reaction is complete, the temperature is lowered to room temperature, the solution is filtered through a filter cloth, and then concentrated under reduced pressure in a temperature atmosphere of 40-80°C. After cooling, a nonpolar organic solvent is added to precipitate NH4FSI crystals, which are then filtered to obtain NH4FSI. The nonpolar organic solvent is an organic solvent that is poorly soluble in NH4FSI, and preferably includes toluene, hexane, dichloromethane, etc.

[0036] The present invention provides a carbonate solution of alkali metal or alkaline earth metal bis(fluorosulfonyl)imide by reacting NH4FSI produced by the above method with an alkali metal salt or alkaline earth metal salt in a mixed solvent of a carbonate solvent and an organic solvent other than carbonate, and removing the organic solvent other than carbonate after the reaction is complete. The above steps are as described above.

[0037] Embodiment The following examples are provided to aid in understanding the present invention, but these examples are provided only to facilitate understanding of the disclosure and the present invention is not limited thereto. [Examples]

[0038] Example 1: Production of Lithium Bis(Fluorosulfonyl)imide Liquid Type (1) Manufacturing of HCSI Chlorosulfonyl isocyanate and chlorosulfonic acid were added to a dry reactor, sealed, and then nitrogen gas was introduced. The molar ratio of chlorosulfonyl isocyanate to chlorosulfonic acid was 1:1.05. The mixture was then heated to 120°C under a nitrogen atmosphere, and the reaction was carried out for 24 hours while maintaining this temperature and slowly stirring. After the reaction was complete, the temperature of the reaction mixture was lowered to 50°C to obtain bis(chlorosulfonyl)imide (HCSI).

[0039] (2) Manufacturing of NH4FSI Ammonium fluoride and butyl acetate were placed in a dry reactor, sealed, and then nitrogen gas was introduced. Under a nitrogen gas atmosphere, the HCSI obtained in step (1) was slowly added dropwise to the reactor. At this time, the internal temperature of the reactor was maintained at 15-20°C, and the molar ratio of HCSI to ammonium fluoride was 1:4. The organic solvent butyl acetate was used at a weight ratio of 4.5 times that of HCSI. After the dropwise addition was complete, the temperature was raised to 75°C under a nitrogen gas atmosphere, and the reaction was carried out for 4 hours while slowly stirring and maintaining this temperature.

[0040] Once the reaction was complete, the reactor temperature was lowered to room temperature, and the completed solution was filtered through a filter cloth. After being concentrated under reduced pressure at a temperature of 60°C, it was cooled, and toluene, a nonpolar organic solvent, was added at a weight ratio of 2:1 relative to HCSI. The recrystallized reaction solution was then filtered through a Nutche filter to obtain ammonium bis(fluorosulfonyl)imide (NH4FSI) crystals.

[0041] The yield of the synthesized NH4FSI crystals was 85.7%, and the purity was 98.2%.

[0042] (3) Manufacturing of LiFSI liquid type NH4FSI, lithium hydroxide, methanol, and ethyl methyl carbonate were added to a dry reactor, which was then sealed and nitrogen gas was introduced. At this time, the internal temperature of the reactor was maintained at room temperature, and the molar ratio of NH4FSI to lithium hydroxide was 1:1.2. The organic solvent was used at a weight ratio of twice that of NH4FSI, and the content ratio of methanol to ethyl methyl carbonate was 2:8. The reaction was then carried out for 3 hours under a nitrogen gas atmosphere with slow stirring while maintaining room temperature.

[0043] Once the reaction was complete, the reaction solution was filtered through a filter cloth, and the methanol was concentrated to less than 100 ppm under reduced pressure at a temperature of 50°C. After confirming the removal of the methanol solvent, ethyl methyl carbonate solvent was added to adjust the weight ratio of lithium bis(fluorosulfonyl)imide (LiFSI) to organic solvent to 3:7 to obtain liquid LiFSI.

[0044] The synthesized LiFSI liquid type was confirmed to have a yield of 95.2%, a purity of 99.93%, and a water content of 10.3 ppm.

[0045] The LiFSI content was calculated by measuring the organic solvent content using gas chromatography.

[0046] F - Cl - SO4 2- The ion content was measured by ion chromatography.

[0047] Examples 2 to 15 Lithium bis(fluorosulfonyl)imide liquid type was produced in the same manner as in Example 1 above. In the three-step production process, the reaction solvent was changed from ethyl methyl carbonate to a carbonate solvent as shown in Table 1 below, and the ratio with methanol solvent was changed to carry out Examples 2 to 15, respectively.

[0048] [Table 1]

[0049] As can be seen from the measurement results of impurity content, yield, and purity in Table 1 above, the liquid lithium bis(fluorosulfonyl)imide produced by the liquid-type LiFSI synthesis (3-step) process generally has a yield of 87.6% or higher, a high purity of 97.32% or higher, and a low water content of 16.4 ppm or lower.

[0050] In particular, when using a carbonate solvent to methanol ratio of 8:2, it is possible to produce liquid LiFSI with the lowest impurity content, high yield, and high purity. Among these, it was confirmed that using ethyl methyl carbonate is relatively advantageous in terms of quality compared to other carbonate-based solvents.

[0051] Comparative Examples 1-5: Production of Lithium Bis(Fluorosulfonyl)imide (LiFSI) Liquid Type Lithium bisfluorosulfonylimide liquid type was produced in the same manner as in Example 1 above, and Comparative Examples 1 to 5 were carried out by using only the carbonate solvent (not a mixed solvent) differently in the three-step manufacturing process.

[0052] [Table 2]

[0053] As can be seen from the measurement results of impurity content, yield, and purity in Table 2 above, it can be confirmed that the liquid lithium bis(fluorosulfonyl)imide produced by the liquid-type LiFSI synthesis (3-step) process generally has a yield of 88.4% or less, a low purity of 98.96% or less, and a high water content of 115.5 ppm or less.

[0054] In particular, when using carbonate solvents alone, it was confirmed that the water content in the product was high, which in turn increased the content of impurities generated by the decomposition of LiFSI.

[0055] Examples 16 to 24 Additionally, to confirm the water removal effect in other organic solvents capable of hydrogen bonding, a liquid lithium bisfluorosulfonylimide was prepared in the same manner as in Example 1 above, and Examples 16 to 24 were carried out in a three-step manufacturing process, with different ratios of ethyl methyl carbonate, isopropyl ether, ethyl acetate, and acetone solvents as reaction solvents.

[0056] [Table 3]

[0057] As can be seen from the measurement results of impurity content, yield, and purity in Table 3 above, the liquid lithium bis(fluorosulfonyl)imide produced by the liquid-type LiFSI synthesis (3-step) process generally has a yield of 80.3% or higher, a high purity of 97.24% or higher, and a low water content of 19.2 ppm or lower.

[0058] In particular, it has been confirmed that using isopropyl ether and ethyl methyl carbonate among organic solvents capable of hydrogen bonding offers a relative advantage in terms of quality compared to other organic solvents. [Industrial applicability]

[0059] The alkali metal or alkaline earth metal bis(fluorosulfonyl)imide carbonate solution of the present invention can be used as is as an electrolyte for secondary batteries.

Claims

1. 1) Adding ammonium bis(fluorosulfonyl)imide and an alkali metal salt or alkaline earth metal salt to a reactor under a nitrogen atmosphere, adding carbonate and an organic solvent other than carbonate, and stirring at room temperature for 1 to 7 hours, and 2) The reaction solution from step 1) is filtered and concentrated under reduced pressure at 30-90°C to remove organic solvents other than carbonate. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide containing [the specified substance].

2. The ammonium bis(fluorosulfonyl)imide mentioned above is a) In the first reactor, a step of reacting chlorosulfonyl isocyanate and chlorosulfonic acid under a nitrogen atmosphere to produce bis(chlorosulfonyl)imide, b) In the second reactor, under a nitrogen atmosphere, NH ４ After adding F and the organic solvent, the bis(chlorosulfonyl)imide is added dropwise to the first reactor at 10-30°C. c) After the dropwise addition is complete, the mixture is reacted at 50-90°C for 1-10 hours to produce ammonium bis(fluorosulfonyl)imide. d) The reaction solution from step c) is filtered, concentrated under reduced pressure, and then a poorly soluble organic solvent is added to the ammonium bis(fluorosulfonyl)imide to obtain the ammonium bis(fluorosulfonyl)imide solid phase. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, comprising the above.

3. The method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, wherein the organic solvent other than the carbonate is an organic solvent capable of hydrogen bonding with water, and when removed after the completion of the reaction, if water is present, it is a solvent capable of azeotropic distillation of water.

4. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 3, wherein the organic solvent other than the carbonate is an alcohol, ether, ester, ketone, or amine.

5. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, wherein the organic solvent other than the carbonate is methanol, ethanol, isopropanol, propanol, acetone, dimethyl ether, diethyl ether, isopropyl ether, ethyl acetate, or butyl acetate.

6. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, wherein the carbonate is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, or propylene carbonate.

7. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, wherein the carbonate and the organic solvent other than the carbonate are 50 to 95% by weight of the carbonate and 5 to 50% by weight of the organic solvent other than the carbonate.

8. Said NH ４ The reaction of FSI with alkali metal salts or alkaline earth metal salts involves 1 mole of NH ４ A method for producing an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide carbonate solution according to claim 1, wherein the amount of alkali metal salt or alkaline earth metal salt is 1 mole or more relative to FSI.

9. The method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, wherein the alkali metal or alkaline earth metal in the carbonate solution of the alkali metal or alkaline earth metal bis(fluorosulfonyl)imide is Li, Na, K, Rb, Cs, Mg, or Ca.

10. A method for producing a carbonate solution of an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide according to claim 1, wherein the content of the carbonate solvent and the solvent other than carbonate is 1 to 5 times the weight ratio of ammonium bis(fluorosulfonyl)imide.

11. The method for producing an alkali metal or alkaline earth metal bis(fluorosulfonyl)imide carbonate solution according to claim 1, wherein the MFSI carbonate solution preferably contains 10 to 50% by weight of MFSI and 50 to 90% by weight of the carbonate solvent.

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