Preparation method of bis (trifluoromethylsulfonyl) imide salt

Abstract

The invention discloses a preparation method of bis (trifluoromethylsulfonyl) imide salt, and belongs to the technical field of metal ion battery electrolyte materials, and the preparation method comprises the following steps: mixing trifluoromethylsulfonyl fluoride and organic amine alkali to obtain a mixed solution A; dropwise adding the mixed solution A into a reaction kettle filled with ammonia gas, and completely reacting to generate bis (trifluoromethanesulfonyl) imide quaternary ammonium salt; carrying out reduced pressure distillation on the reaction product to obtain pure bis (trifluoromethanesulfonyl) imide quaternary ammonium salt; the preparation method comprises the following steps: mixing bis (trifluoromethylsulfonyl) imide triethylamine salt and metal salt according to a molar ratio of 1: (1-3), and completely reacting in an organic solvent to generate bis (trifluoromethylsulfonyl) imide salt; and filtering the reaction liquid, and carrying out reduced pressure distillation to obtain the final product bis (trifluoromethylsulfonyl) imide salt. The preparation method provided by the invention has the characteristics of simple process, high yield and high product purity, and solves the problems of complex process, low yield, low product purity and the like in the existing preparation method.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of metal ion battery electrolyte materials, and particularly relates to a preparation method of a bistrifluoromethylsulfonylimide salt (MTFSI). BACKGROUND

[0002] As a kind of efficient energy storage device, lithium ion battery is widely used in consumer electronics, electric vehicles and other fields. As a key component of lithium ion battery, the performance of electrolyte directly affects the energy density, cycle life and safety of the battery. Traditional lithium salt electrolyte, such as lithium hexafluorophosphate (LiPF6), has poor thermal stability and is prone to hydrolysis, which limits its application in high temperature and wide voltage range.

[0003] Bistrifluoromethylsulfonylimide salt has become a potential new type of electrolyte metal salt due to its excellent thermal stability, high electrochemical window and low temperature performance. The CF3SO 2- Group in the structure of bistrifluoromethylsulfonylimide salt has strong electron-withdrawing effect, which aggravates the delocalization of negative charge and reduces ion association pairing, so that the salt has high solubility. And it has high conductivity, and the thermal decomposition temperature is more than 360℃, and it is not easy to hydrolyze. However, MTFSI will seriously corrode Al current collector when the voltage is higher than 3.7V. Therefore, suitable additives are usually used in combination, or the length of perfluoroalkyl chain is extended to improve the corrosion resistance of Al foil in MTFSI electrolyte. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of bistrifluoromethylsulfonylimide salt.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme: A preparation method of bistrifluoromethylsulfonylimide salt, comprising the following steps: (1) Raw material preparation: trifluoromethanesulfonyl fluoride (CF3SO2F) and machine amine base are mixed according to the molar ratio of 1: (1-3) to obtain mixed solution A; (2) Reaction synthesis: slowly add mixed solution A into the reaction kettle containing ammonia gas (NH3), and react to generate bistrifluoromethylsulfonylimide quaternary ammonium salt; (3) Purification treatment: the reaction product is subjected to vacuum distillation to remove unreacted trifluoromethanesulfonyl fluoride and machine amine base, and pure bistrifluoromethylsulfonylimide quaternary ammonium salt is obtained; (4) Metallization reaction: bistrifluoromethylsulfonylimide quaternary ammonium salt is mixed with metal salt according to the molar ratio of 1:1-3, and the reaction is completed in an organic solvent to generate bistrifluoromethylsulfonylimide salt; (5) Post-treatment: the reaction liquid is filtered and vacuum distilled to obtain the final product bistrifluoromethylsulfonylimide salt.

[0006] Further, the organic amine base in step (1) is at least one selected from triethylamine, tripropylamine, tributylamine, pyridine, methylpyridine, pyrimidine and imidazole.

[0007] Further, in step (2), the molar ratio of trifluoromethanesulfonyl fluoride to ammonia is 1: (0.5-1), the reaction temperature is -20-0°C, and the reaction time is 4-8 h.

[0008] Further, in step (4), the metal salt is LiOH, Li2CO3, NaOH or Na2CO3, and the reaction time is 12-24 h.

[0009] Further, in step (4), the organic solvent is at least one selected from anhydrous ether, anhydrous dichloromethane, cyclohexane and toluene, and the concentration of the bistrifluoromethanesulfonylimide quaternary ammonium salt in the organic solvent is 30-40 wt%.

[0010] Further, in steps (3) and (5), the reduced pressure distillation refers to distillation under the conditions of a temperature of 40-50°C and a vacuum degree of 10-20 Pa.

[0011] Further, in steps (2) and (4), the reaction is carried out under stirring.

[0012] The preparation method has the characteristics of simple process, high yield and high product purity, and solves the problems of complex process, low yield and low product purity in the existing preparation method. DETAILED DESCRIPTION

[0013] The technical solutions of the present application are further described below in combination with specific embodiments.

[0014] A preparation method of a bistrifluoromethylsulfonylimide salt, comprising the following steps: Raw material preparation: trifluoromethanesulfonyl fluoride (CF3SO2F) and triethylamine (Et3N) are mixed in a molar ratio of 1:1-3 to obtain a mixed solution A.

[0015] Reaction synthesis: the mixed solution A is slowly added to a reaction kettle containing ammonia (NH3), and stirred at a temperature of -20-0°C for 4-8 h to generate bistrifluoromethanesulfonylimide triethylamine salt ((CF3SO2)2NH·Et3N).

[0016] Purification treatment: the reaction product is subjected to reduced pressure distillation to remove unreacted trifluoromethanesulfonyl fluoride and triethylamine, and obtain pure bistrifluoromethanesulfonylimide triethylamine salt.

[0017] Lithiation: mixing bistrifluoromethanesulfonimide triethylamine salt and metal salt with a molar ratio of 1:1~3, stirring the reaction in anhydrous ether for 12-24 hours to generate bistrifluoromethylsulfonimide salt.

[0018] Post-processing: filtering the reaction solution to remove unreacted metal salt, then performing vacuum distillation to remove the solvent to obtain the final product bistrifluoromethylsulfonimide salt.

[0019] Example 1: A method for preparing bistrifluoromethylsulfonimide salt, comprising the following steps: S1, mixing trifluoromethanesulfonyl fluoride and triethylamine with a molar ratio of 1:1 to obtain a mixed solution A. S2, slowly adding the mixed solution A into the reaction kettle containing ammonia gas, the molar ratio of trifluoromethanesulfonyl fluoride to ammonia gas is 2:1, stirring the reaction at-5℃ for 8h to generate bistrifluoromethanesulfonimide triethylamine salt.

[0020] S3, performing vacuum distillation on the reaction product at a temperature of 50℃ and a vacuum degree of 20Pa to remove unreacted trifluoromethanesulfonyl fluoride and triethylamine, obtaining pure bistrifluoromethanesulfonimide triethylamine salt.

[0021] S4, mixing bistrifluoromethanesulfonimide triethylamine salt with LiOH, the molar ratio of bistrifluoromethanesulfonimide triethylamine salt to lithium hydroxide is 1:1, stirring the reaction in anhydrous ether (the concentration of bistrifluoromethanesulfonimide triethylamine salt in anhydrous ether is 35wt%) for 18h to generate bistrifluoromethylsulfonimide salt.

[0022] S5, filtering the reaction solution with filter paper in a positive pressure filter to remove unreacted LiOH, then performing vacuum distillation at a temperature of 40℃ and a vacuum degree of 10Pa to remove the solvent, obtaining the final product bistrifluoromethylsulfonimide salt.

[0023] Example 2: A method for preparing bistrifluoromethylsulfonimide salt, comprising the following steps: S1, mixing trifluoromethanesulfonyl fluoride and triethylamine with a molar ratio of 1:2 to obtain a mixed solution A.

[0024] S2, slowly adding the mixed solution A into the reaction kettle containing ammonia gas, the molar ratio of trifluoromethanesulfonyl fluoride to ammonia gas is 2:1, stirring the reaction at-10℃ for 5h to generate bistrifluoromethanesulfonimide triethylamine salt.

[0025] S3, performing vacuum distillation on the reaction product at a temperature of 50℃ and a vacuum degree of 20Pa to remove unreacted trifluoromethanesulfonyl fluoride and triethylamine, obtaining pure bistrifluoromethanesulfonimide triethylamine salt.

[0026] S4, mixing the bistrifluoromethanesulfonylimide triethylamine salt with LiOH, the molar ratio of the bistrifluoromethanesulfonylimide triethylamine salt to lithium hydroxide being 1:2, stirring the mixture in anhydrous ether (the concentration of the bistrifluoromethanesulfonylimide triethylamine salt in the anhydrous ether being 35wt%) for 18h to generate the bistrifluoromethylsulfonylimide salt.

[0027] S5, filtering the reaction solution with filter paper in a positive pressure filter to remove the unreacted LiOH, and then performing vacuum distillation under the conditions of a temperature of 40℃ and a vacuum degree of 10Pa to remove the solvent, thereby obtaining the final product, the bistrifluoromethylsulfonylimide salt.

[0028] Example 3: A method for preparing a bistrifluoromethylsulfonylimide salt, comprising the following steps: S1, mixing trifluoromethanesulfonyl fluoride and triethylamine according to a molar ratio of 1:2 to obtain a mixed solution A.

[0029] S2, slowly adding the mixed solution A into a reaction kettle containing ammonia gas, the molar ratio of trifluoromethanesulfonyl fluoride to ammonia gas being 2:1, stirring the mixture at -15℃ for 4h to generate a bistrifluoromethanesulfonylimide triethylamine salt.

[0030] S3, performing vacuum distillation on the reaction product under the conditions of a temperature of 50℃ and a vacuum degree of 20Pa to remove the unreacted trifluoromethanesulfonyl fluoride and triethylamine, thereby obtaining a pure bistrifluoromethanesulfonylimide triethylamine salt.

[0031] S4, mixing the bistrifluoromethanesulfonylimide triethylamine salt with LiOH, the molar ratio of the bistrifluoromethanesulfonylimide triethylamine salt to lithium hydroxide being 1:2, stirring the mixture in anhydrous ether (the concentration of the bistrifluoromethanesulfonylimide triethylamine salt in the anhydrous ether being 35wt%) for 14h to generate the bistrifluoromethylsulfonylimide salt.

[0032] S5, filtering the reaction solution with filter paper in a positive pressure filter to remove the unreacted LiOH, and then performing vacuum distillation under the conditions of a temperature of 40℃ and a vacuum degree of 10Pa to remove the solvent, thereby obtaining the final product, the bistrifluoromethylsulfonylimide salt.

[0033] Example 4: A method for preparing a bistrifluoromethylsulfonylimide salt, comprising the following steps: S1, mixing trifluoromethanesulfonyl fluoride and triethylamine according to a molar ratio of 1:3 to obtain a mixed solution A.

[0034] S2, slowly adding the mixed solution A into a reaction kettle containing ammonia gas, the molar ratio of trifluoromethanesulfonyl fluoride to ammonia gas being 2:1, stirring the mixture at -10℃ for 6h to generate a bistrifluoromethanesulfonylimide triethylamine salt.

[0035] S3, the reaction product is subjected to vacuum distillation under the conditions of a temperature of 50℃ and a vacuum degree of 20Pa, to remove unreacted trifluoromethylsulfonyl fluoride and triethylamine, to obtain pure bistrifluoromethylsulfonimide triethylamine salt.

[0036] S4, the bistrifluoromethylsulfonimide triethylamine salt is mixed with Li2CO3, the molar ratio of the bistrifluoromethylsulfonimide triethylamine salt to lithium carbonate is 1:2, and the mixture is stirred in anhydrous ether (the concentration of the bistrifluoromethylsulfonimide triethylamine salt in the anhydrous ether is 35wt%) for 12h to generate lithium bistrifluoromethylsulfonimide.

[0037] S5, the reaction solution is filtered in a positive pressure filter using filter paper to remove unreacted LiOH, and then vacuum distillation is performed under the conditions of a temperature of 40℃ and a vacuum degree of 10Pa to remove the solvent, to obtain the final product, bistrifluoromethylsulfonimide salt.

[0038] Example 5: A method for preparing bistrifluoromethylsulfonimide salt, comprising the following steps: S1, trifluoromethylsulfonyl fluoride and triethylamine are mixed according to a molar ratio of 1:1 to obtain a mixed solution A.

[0039] S2, the mixed solution A is slowly added to a reaction kettle containing ammonia gas, the molar ratio of trifluoromethylsulfonyl fluoride to ammonia gas is 2:1, and stirring is performed at -5℃ for 6h to generate bistrifluoromethylsulfonimide triethylamine salt.

[0040] S3, the reaction product is subjected to vacuum distillation under the conditions of a temperature of 50℃ and a vacuum degree of 20Pa, to remove unreacted trifluoromethylsulfonyl fluoride and triethylamine, to obtain pure bistrifluoromethylsulfonimide triethylamine salt.

[0041] S4, the bistrifluoromethylsulfonimide triethylamine salt is mixed with NaOH, the molar ratio of the bistrifluoromethylsulfonimide triethylamine salt to sodium hydroxide is 1:1, and the mixture is stirred in anhydrous ether (the concentration of the bistrifluoromethylsulfonimide triethylamine salt in the anhydrous ether is 35wt%) for 18h to generate lithium bistrifluoromethylsulfonimide.

[0042] S5, the reaction solution is filtered in a positive pressure filter using filter paper to remove unreacted NaOH, and then vacuum distillation is performed under the conditions of a temperature of 40℃ and a vacuum degree of 10Pa to remove the solvent, to obtain the final product, bistrifluoromethylsulfonimide salt.

[0043] Example 6: A method for preparing bistrifluoromethylsulfonimide salt, comprising the following steps: S1, trifluoromethylsulfonyl fluoride and triethylamine are mixed according to a molar ratio of 1:1 to obtain a mixed solution A.

[0044] S2, slowly drop the mixed solution A into the reactor containing ammonia, the molar ratio of trifluoromethanesulfonyl fluoride and ammonia is 2:1, and the reaction is stirred at-10℃ for 8h to generate bistrifluoromethanesulfonimide triethylamine salt.

[0045] S3, the reaction product is subjected to vacuum distillation under the conditions of temperature 50℃ and vacuum degree 20Pa to remove unreacted trifluoromethanesulfonyl fluoride and triethylamine, and pure bistrifluoromethanesulfonimide triethylamine salt is obtained.

[0046] S4, the bistrifluoromethanesulfonimide triethylamine salt is mixed with Na2CO3, the molar ratio of bistrifluoromethanesulfonimide triethylamine salt and sodium carbonate is 1:1, and the reaction is stirred in anhydrous ether (the concentration of bistrifluoromethanesulfonimide triethylamine salt in anhydrous ether is 35wt%) for 20h to generate lithium bistrifluoromethylsulfonimide.

[0047] S5, the reaction solution is filtered in a positive pressure filter with filter paper to remove unreacted Na2CO3, and then vacuum distillation is carried out under the conditions of temperature 40℃ and vacuum degree 10Pa to remove the solvent, and the final product bistrifluoromethylsulfonimide salt is obtained.

[0048] The analysis and detection results of the above examples are as follows: From the above results, it can be seen that the lower the reaction synthesis stage temperature, the longer the lithiation time, and the higher the product yield, which can basically reach more than 91%, and the purity can reach more than 99.90%, and the corresponding water content and chlorine content are also low.

[0049] The preparation method of the bistrifluoromethylsulfonimide salt of the application has the characteristics of simple process, high yield and high product purity, and no other solvents are involved in the raw material preparation process, so that the reaction product is easy to separate and the post-treatment process is simple; secondly, the reaction does not require a catalyst, avoiding the problems of poor stability and easy decomposition of the catalyst. The bistrifluoromethylsulfonimide salt of the application can be used as a battery electrolyte, has excellent electrochemical performance and thermal stability, and has a broad application prospect.

Claims

1. A process for the preparation of a bistrifluoromethylsulfonimide salt, characterized in that, The method comprises the following steps: (1) mixing trifluoromethanesulfonyl fluoride and an organic amine base in a molar ratio of 1:(1-3) to obtain a mixed solution A; (2) adding the mixed solution A into a reaction kettle containing ammonia gas to generate a bistrifluoromethanesulfonylimide quaternary ammonium salt; (3) performing vacuum distillation on the reaction product to obtain pure bistrifluoromethanesulfonylimide quaternary ammonium salt; (4) mixing the bistrifluoromethanesulfonylimide quaternary ammonium salt with a metal salt in a molar ratio of 1:1-3, and performing a reaction in an organic solvent to generate a bistrifluoromethylsulfonylimide salt; (5) filtering and vacuum distilling the reaction solution to obtain the final product bistrifluoromethylsulfonylimide salt.

2. The process for the preparation of the bis-trifluoromethylsulfonylimide salt according to claim 1, characterized in that, The organic amine base in step (1) is at least one selected from triethylamine, tripropylamine, tributylamine, pyridine, methylpyridine, pyrimidine and imidazole.

3. The method of preparing the bis-trifluoromethylsulfonimide salt according to claim 1, characterized in that, In step (2), the molar ratio of trifluoromethanesulfonyl fluoride to ammonia gas is 1:(0.5-1), the reaction temperature is-20-0°C, and the reaction time is 4-8 h.

4. The method of preparing the bis-trifluoromethylsulfonimide salt according to claim 1, characterized by, In step (4), the metal salt is LiOH, Li2CO3, NaOH or Na2CO3, and the reaction time is 12-24 h.

5. The method of preparing the bis-trifluoromethylsulfonimide salt according to claim 1, characterized by, In step (4), the organic solvent is at least one selected from anhydrous ether, anhydrous dichloromethane, cyclohexane and toluene, and the concentration of the bistrifluoromethanesulfonylimide quaternary ammonium salt in the organic solvent is 30-40 wt%.

6. The method of preparing the bis-trifluoromethylsulfonimide salt according to claim 1, characterized by, In steps (3) and (5), the vacuum distillation is performed at a temperature of 40-50°C and a vacuum degree of 10-20 Pa.

7. The method of preparing the bis-trifluoromethylsulfonimide salt according to claim 1, characterized by, In steps (2) and (4), the reaction is performed under stirring.

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