Preparation method of lithium trifluoromethanesulfinate

Abstract

The invention discloses a preparation method of lithium trifluoromethanesulfinate, and belongs to the field of lithium ion battery materials. The preparation method of the lithium trifluoromethanesulfinate comprises the following steps: 1, mixing trifluoromethanesulfonyl chloride, lithium sulfite, lithium bicarbonate and a first solvent, and heating to react; 2, dissolving the concentrated crude product in a second solvent, and filtering and separating a lithium sulfate solid; and 3, concentrating the filtrate, adding a third solvent, uniformly stirring, filtering and separating the lithium chloride solid, and concentrating to obtain the lithium trifluoromethanesulfinate. According to the method for preparing the lithium trifluoromethanesulfinate, the yield can reach 94%, the operation is simple, byproducts are easy to separate, and the method is suitable for industrial production. In addition, the obtained by-product lithium sulfate can be used for preparing lithium sulfide, the by-product lithium chloride can be used for preparing solid electrolyte, and resource utilization is achieved.

Description

Technical Field

[0001] The invention belongs to the field of lithium ion battery materials, and particularly relates to a method for preparing lithium trifluoromethanesulfinate. Background Art

[0002] Lithium-ion batteries, with their high energy density, fast charging, and environmentally friendly advantages, have been widely adopted in energy storage projects. However, lithium-ion batteries are prone to capacity degradation due to lithium ion depletion during use, which in turn increases recycling costs. To address these challenges, a new lithium ion carrier molecule, lithium trifluoromethanesulfinate (LiCF3SO2), has emerged. This material can significantly extend the lifespan of lithium batteries by up to tenfold.

[0003] Patent CN 116487713 A discloses a method for preparing lithium trifluoromethanesulfinate. This involves recrystallizing purchased sodium trifluoromethanesulfinate, acidifying it, and then reacting it with lithium hydroxide to produce lithium trifluoromethanesulfinate. This method is simple and highly safe, but sodium trifluoromethanesulfinate is expensive, increasing production costs.

[0004] The journal "External Li Supply Reshapes Li Deficiency and Lifetime Limit of Batteries" discloses a method for preparing lithium trifluoromethanesulfinate. This method uses trifluoromethanesulfonyl chloride and sodium sulfite to prepare sodium trifluoromethanesulfinate, which is then reacted with lithium hydroxide to form lithium trifluoromethanesulfinate. This method avoids the cost of purchasing sodium trifluoromethanesulfinate, but the reaction produces a large amount of sodium salt, making it difficult to use in lithium batteries.

[0005] In summary, the current preparation of lithium trifluoromethanesulfinate involves the lithiation process of sodium trifluoromethanesulfinate, which has the problems of high production cost, large by-product volume, and difficulty in resource utilization. Summary of the Invention

[0006] To address the above problems, the present invention provides a method for preparing lithium trifluoromethanesulfinate, which enables low-cost production of lithium trifluoromethanesulfinate. The by-products, lithium sulfate and lithium chloride, can be used as battery materials after purification, thus realizing resource utilization of the by-products.

[0007] The present invention is achieved through the following technical solutions: The preparation method of lithium trifluoromethanesulfinate of the present invention comprises the following steps: 1) Mix trifluoromethanesulfonyl chloride, lithium sulfite, lithium bicarbonate and the first solvent in a certain proportion, and react at 60-70°C for 1-4 hours; 2) The first solvent is evaporated from the reaction solution in step (1), the second solvent is added and stirred, and the reaction solution is filtered to remove the lithium sulfate solid; 3) The second solvent is evaporated from the filtrate of step (2), and a third solvent is added. The mixture is stirred at room temperature for 0.5 to 1 hour. The reaction solution is filtered to remove lithium chloride solid, and the reaction solution is concentrated to obtain lithium trifluoromethanesulfinate.

[0008] According to the preparation method of lithium trifluoromethanesulfinate, the first solvent in step (1) is at least one of water, ethanol, and propanol, and the amount of the solvent is 1 to 3 times the mass of trifluoromethanesulfonyl chloride.

[0009] According to the preparation method of lithium trifluoromethanesulfinate, the molar ratio of the added amounts of trifluoromethanesulfonyl chloride, lithium sulfite and lithium bicarbonate in step (1) is 1:2~2.5:3~3.5.

[0010] According to the preparation method of lithium trifluoromethanesulfinate, the second solvent in step (2) is an A+B mixed solvent, the mass ratio of A to B is 1.4:1, A is any one of isopropanol, propanol, ethanol, and methanol, B is any one of acetonitrile, dichloromethane, toluene, and ethyl acetate, and the amount of solvent added is 1 to 3 times the mass of trifluoromethanesulfonyl chloride.

[0011] According to the preparation method of lithium trifluoromethanesulfinate, solvent A is isopropanol or propanol, and solvent B is ethyl acetate or acetonitrile.

[0012] According to the preparation method of lithium trifluoromethanesulfinate, the third solvent in step (3) is a C+D mixed solvent, wherein C is any one of diethyl ether, dichloromethane, and N,N-dimethylformamide, and the amount of C is 0.5 to 2 times the mass of trifluoromethanesulfonyl chloride, and D is hydrochloric acid, and the amount of hydrochloric acid is 0.5 times the molar amount of trifluoromethanesulfonyl chloride.

[0013] The beneficial effects achieved by the present invention are: The lithium trifluoromethanesulfinate product prepared by the present invention has high purity and higher product yield. Compared with traditional methods, the preparation method of lithium trifluoromethanesulfinate provided by the present invention has reduced raw material costs and simplified processes. The obtained by-products lithium sulfate and lithium chloride are easy to separate and can be utilized as resources. The lithium sulfate can be used to prepare lithium sulfide, and the lithium chloride can be used to prepare solid electrolytes. The specific preparation method and application of the lithium trifluoromethanesulfinate are not described in detail in the present invention. DETAILED DESCRIPTION

[0014] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention.

[0015] The preparation method of lithium trifluoromethanesulfinate of the present invention comprises the following steps: 1) Mix trifluoromethanesulfonyl chloride, lithium sulfite, lithium bicarbonate, and a first solvent in a specific proportion and incubate at 60-70°C for 1-4 hours. The molar ratio of trifluoromethanesulfonyl chloride, lithium sulfite, and lithium bicarbonate is 1:2-2.5:3-3.5. The first solvent is at least one of water, ethanol, and propanol, and the amount of the solvent is 1-3 times the mass of the trifluoromethanesulfonyl chloride. 2) The first solvent is evaporated from the reaction solution in step (1), and a second solvent is added and stirred, and the reaction solution is filtered to remove the lithium sulfate solid; the second solvent is an A+B mixed solvent, the mass ratio of A to B is 1.4:1, the A is any one of isopropanol, propanol, ethanol, and methanol, and B is any one of acetonitrile, dichloromethane, toluene, and ethyl acetate, and the amount of solvent added is 1 to 3 times the mass of trifluoromethylsulfonyl chloride; 3) The second solvent is evaporated from the filtrate of step (2), and a third solvent is added, and the mixture is stirred at room temperature for 0.5 to 1 hour. The three solvents are a C+D mixed solvent, wherein C is any one of diethyl ether, dichloromethane, and N,N-dimethylformamide, and the amount of C is 0.5 to 2 times the mass of trifluoromethylsulfonyl chloride. D is hydrochloric acid, and the amount of hydrochloric acid is 0.5 times the molar amount of trifluoromethylsulfonyl chloride. After stirring, the reaction solution is filtered to remove the lithium chloride solid, and the reaction solution is finally concentrated to obtain lithium trifluoromethylsulfinate.

[0016] The content of the present invention is further described below with specific parameters. Example 1

[0017] (1) Add 250 g of trifluoromethylsulfonyl chloride, 348 g of lithium sulfite, 250 g of ethanol and 250 g of water into a 2 L reactor, add 353 g of lithium bicarbonate, start stirring, heat to 70 ° C and react for 4 hours; (2) After the reaction, the reaction solution was evaporated to remove the mixed solvent, 175 g of isopropyl alcohol and 125 g of toluene were added, and the solid was precipitated by stirring. The lithium sulfate solid was separated by filtration. The lithium sulfate solid was tested by ICP and ion chromatography, and the solid purity was 99.94%; (3) The filtrate was evaporated to remove the mixed solvent, 125 g of dichloromethane and 73 g of hydrochloric acid were added, and the mixture was stirred at room temperature for 0.5 h. The lithium chloride solid was separated by filtration, and the filtrate was concentrated to obtain lithium trifluoromethanesulfinate product with a purity of 99.62% and a yield of 94%. Example 2

[0018] (1) Add 250 g of trifluoromethylsulfonyl chloride, 348 g of lithium sulfite, 250 g of ethanol and 250 g of water into a 2 L reactor, add 353 g of lithium bicarbonate, start stirring, heat to 70 ° C and react for 4 hours; (2) After the reaction, the reaction solution was evaporated to remove the mixed solvent, 300 g of ethyl acetate was added, and the mixture was stirred to precipitate solids. The lithium sulfate solids were separated by filtration. The purity of the solids was 92.73% as determined by ICP and ion chromatography. (3) The filtrate was evaporated to remove the solvent, 125 g of dichloromethane and 73 g of hydrochloric acid were added, and the mixture was stirred at room temperature for 0.5 h. The lithium chloride solid was separated by filtration, and the filtrate was concentrated to obtain lithium trifluoromethanesulfinate product with a purity of 97.23% and a yield of 92%. Example 3

[0019] (1) Add 250 g of trifluoromethylsulfonyl chloride, 348 g of lithium sulfite and 500 g of water into a 2 L reactor, add 353 g of lithium bicarbonate, start stirring, heat to 70 ° C and react for 4 hours; (2) After the reaction, the reaction solution was evaporated to remove the solvent, 175 g of isopropyl alcohol and 125 g of ethyl acetate were added, and the solid was precipitated by stirring. The lithium sulfate solid was separated by filtration. The lithium sulfate solid was tested by ICP and ion chromatography, and the solid purity was 99.02%; (3) The filtrate was evaporated to remove the mixed solvent, 125 g of dichloromethane and 73 g of hydrochloric acid were added, and the mixture was stirred at room temperature for 0.5 h. The lithium chloride solid was separated by filtration, and the filtrate was concentrated to obtain lithium trifluoromethanesulfinate product with a purity of 99.58% and a yield of 85%. Example 4

[0020] (1) Add 250 g of trifluoromethylsulfonyl chloride, 279 g of lithium sulfite and 500 g of ethanol into a 2 L reactor, add 302 g of lithium bicarbonate, start stirring, heat to 60 ° C and react for 1 hour; (2) After the reaction, the reaction solution was evaporated to remove the solvent, 175 g of isopropyl alcohol and 125 g of toluene were added, and the solid was precipitated by stirring. The lithium sulfate solid was separated by filtration. The lithium sulfate solid was tested by ICP and ion chromatography, and the solid purity was 99.92%; (3) The filtrate was evaporated to remove the mixed solvent, 125 g of N,N-dimethylformamide and 73 g of hydrochloric acid were added, and stirred at room temperature for 0.5 h. The lithium chloride solid was separated by filtration, and the filtrate was concentrated to obtain lithium trifluoromethanesulfinate product with a purity of 97.38% and a yield of 72%. Comparative Example 1

[0021] (1) Add 250 g of trifluoromethylsulfonyl chloride, 279 g of lithium sulfite and 500 g of water into a 2 L reactor, add 302 g of lithium bicarbonate, start stirring, heat to 60 ° C and react for 1 hour; (2) After the reaction, the reaction solution was evaporated to remove the solvent, 175 g of isopropyl alcohol and 125 g of ethyl acetate were added, and the solid was precipitated by stirring. The lithium sulfate solid was separated by filtration. The lithium sulfate solid was tested by ICP and ion chromatography, and the solid purity was 98.86%; (3) The filtrate was evaporated to remove the mixed solvent, 125 g of ether and 74 g of hydrochloric acid were added, and the mixture was stirred at room temperature for 0.5 h. The lithium chloride solid was separated by filtration, and the filtrate was concentrated to obtain lithium trifluoromethanesulfinate product with a purity of 99.31% and a yield of 66%. Comparative Example 2

[0022] (1) Add 250 g of trifluoromethylsulfonyl chloride, 279 g of lithium sulfite and 500 g of isopropyl alcohol into a 2 L reactor, add 302 g of lithium bicarbonate, start stirring, heat to 60 ° C and react for 1 hour; (2) After the reaction, the reaction solution was evaporated to remove the solvent, 175 g of isopropyl alcohol and 125 g of toluene were added, and the solid was precipitated by stirring. The lithium sulfate solid was separated by filtration. The lithium sulfate solid was tested by ICP and ion chromatography, and the solid purity was 99.72%; (3) The filtrate was evaporated to remove the mixed solvent, 125 g of N,N-dimethylformamide and 73 g of hydrochloric acid were added, and stirred at room temperature for 0.5 h. The lithium chloride solid was separated by filtration, and the filtrate was concentrated to obtain lithium trifluoromethanesulfinate product with a purity of 96.44% and a yield of 68%.

[0023] The yield and purity of lithium trifluoromethanesulfinate and the purity of lithium sulfate obtained in the examples and comparative examples are shown in Table 1.

[0024] Table 1: Raw material molar ratio temperature time First solvent Second solvent The third solvent Product yield Product purity Lithium sulfate purity Example 1 1:2.5:3.5 70℃ 4h Ethanol, water Isopropyl alcohol, toluene Dichloromethane, hydrochloric acid 94% 99.62% 99.94% Example 2 1:2.5:3.5 70℃ 4h Ethanol, water Ethyl acetate Dichloromethane, hydrochloric acid 92% 97.23% 92.73% Example 3 1:2.5:3.5 70℃ 4h water Isopropyl alcohol, ethyl acetate Dichloromethane, hydrochloric acid 85% 99.58% 99.02% Example 4 1:2.0:3.0 60℃ 1h ethanol Isopropyl alcohol, toluene N,N-dimethylformamide, hydrochloric acid 72% 97.38% 99.92% Comparative Example 1 1:2.0:3.0 60℃ 1h water Isopropyl alcohol, ethyl acetate Ether, hydrochloric acid 66% 99.31% 98.86% Comparative Example 2 1:2.0:3.0 60℃ 1h Isopropyl alcohol Isopropyl alcohol, toluene N,N-dimethylformamide, hydrochloric acid 68% 96.44% 99.72% The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing lithium trifluoromethanesulfinate, characterized in that: The following steps are involved: (1) trifluoromethanesulfonyl chloride, lithium sulfite, lithium bicarbonate and the first solvent are mixed in a certain proportion and kept at 60-70°C for 1-4 hours; (2) The first solvent is evaporated from the reaction solution in step (1), the second solvent is added and stirred, and the reaction solution is filtered to remove the lithium sulfate solid; (3) The second solvent is evaporated from the filtrate of step (2), and the third solvent is added. The mixture is stirred at room temperature for 0.5 to 1 hour. The reaction solution is filtered to remove lithium chloride solid, and the reaction solution is finally concentrated to obtain lithium trifluoromethanesulfinate.

2. The method for preparing lithium trifluoromethanesulfinate according to claim 1, wherein The first solvent in step (1) is at least one of water, ethanol, and propanol, and the amount of the solvent used is 1 to 3 times the mass of trifluoromethylsulfonyl chloride.

3. The method for preparing lithium trifluoromethanesulfinate according to claim 1, wherein In step (1), the molar ratio of the added amounts of trifluoromethylsulfonyl chloride, lithium sulfite and lithium bicarbonate is 1:2~2.5:3~3.

5.

4. The method for preparing lithium trifluoromethanesulfinate according to claim 1, wherein The second solvent in step (2) is an A+B mixed solvent, the mass ratio of A to B is 1.4:1, A is any one of isopropanol, propanol, ethanol, and methanol, B is any one of acetonitrile, dichloromethane, toluene, and ethyl acetate, and the amount of solvent added is 1 to 3 times the mass of trifluoromethylsulfonyl chloride.

5. The method for preparing lithium trifluoromethanesulfinate according to claim 4, wherein: Solvent A is isopropanol or propanol, and solvent B is ethyl acetate or acetonitrile.

6. The method for preparing lithium trifluoromethanesulfinate according to claim 1, wherein: The third solvent in step (3) is a C+D mixed solvent, wherein C is any one of diethyl ether, dichloromethane, and N,N-dimethylformamide, and the amount of C is 0.5 to 2 times the mass of trifluoromethylsulfonyl chloride, and D is hydrochloric acid, and the amount of hydrochloric acid is 0.5 times the molar amount of trifluoromethylsulfonyl chloride.