Preparation method of ethylene sulfonic acid lithium difluorophosphate triethylamine salt
An improved preparation method was developed, which utilizes the reaction of sodium hydroxyethyl sulfonate with a chlorinating agent to generate triethylamine ethylene sulfonate, which then coordinates with lithium difluorophosphate. This method solves the problem of low purity in existing technologies and achieves the preparation of high-yield and high-purity triethylamine ethylene sulfonate difluorophosphate, making it suitable for industrial applications.
Patent Information
- Application Number
- CN202410751008.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-12
- Publication Date
- 2025-12-12
AI Technical Summary
In the existing process for synthesizing lithium triethylamine difluorophosphate, the raw material sodium vinyl sulfonate solution contains a large amount of impurity salts, resulting in low product purity that fails to meet the requirements for lithium battery electrolyte additives.
The synthesis steps were simplified and the purity was improved by reacting sodium hydroxyethyl sulfonate with excess chlorination reagent to generate chloroethane sulfonyl chloride, which then reacted with triethylamine to generate triethylamine vinyl sulfonate, followed by coordination reaction with lithium difluorophosphate. By controlling the reaction conditions and using an inert organic solvent for crystallization, the synthesis steps were simplified and the purity was improved.
It improves the yield and purity of lithium difluorophosphate triethylamine salt of ethylene sulfonate, reduces raw material costs, and is suitable for industrial production.
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Figure CN121108020A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of additives in lithium ion battery electrolyte, and in particular to a preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt. BACKGROUND
[0002] In recent years, the vigorous development of the lithium battery new energy industry, people's research on electrolyte lithium salt is deepening. Because inorganic anion electrolyte lithium salt such as lithium hexafluorophosphate, lithium difluorophosphate, although has high conductivity and cycle efficiency, but has strong hygroscopicity and poor thermal stability, has safety hidden trouble at high temperature or high current density, is not conducive to the development of high energy and power density lithium ion battery.
[0003] Lithium ethylenesulfonate difluorophosphate triethylamine salt as a good performance electrolyte additive, can generate a layer of stable and dense protective film on the electrode surface through redox reaction, avoid the continuous decomposition of electrolyte on the surface of positive material, thereby improving the cycle performance of lithium battery, effectively improving the high temperature stability of lithium battery, and its moisture is more stable, the production and storage conditions are not harsh, which is conducive to industrialized production.
[0004] At present, the known synthesis process route of lithium ethylenesulfonate difluorophosphate triethylamine salt is disclosed in patent document CN116143666: first, triethylamine sulfate is prepared by reacting triethylamine and dilute sulfuric acid, then reacting with sodium ethylenesulfonate to obtain triethylamine ethylenesulfonate, and finally, lithium difluorophosphate is coordinated to obtain lithium ethylenesulfonate difluorophosphate triethylamine salt. But the defects of this method are: the raw material sodium ethylenesulfonate solution contains a lot of impurity salt, which leads to low purity of the final product, high content of impurity metal ions, and cannot meet the requirements of lithium battery electrolyte additive indicators. SUMMARY
[0005] The purpose of the present application is to provide a preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, which has low raw material cost, simple preparation process, high yield and is suitable for industrial production.
[0006] To achieve the above object, the technical scheme adopted by the present application is: a preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, comprising the following steps: I. sodium hydroxyethyl sulfonate is subjected to chlorination reaction with excess chlorination reagent in a chlorination reaction solvent to obtain chloroethane sulfuryl chloride, which is then hydrolyzed into chloroethane sulfonic acid, and then elimination and acid-base neutralization reaction with excess triethylamine to obtain vinyl sulfonic acid triethylamine salt; the chlorination reagent is selected from one of sulfurous chloride, oxalyl chloride, sulfuryl chloride, phosphorus oxychloride, phosphorus trichloride and phosphorus pentachloride, and the chlorination reaction solvent is selected from one of toluene, dichloroethane and acetonitrile; the chlorination reaction temperature is controlled at 25-100 DEG C; II. in a polar organic solvent, the vinyl sulfonic acid triethylamine salt is subjected to coordination reaction with lithium difluorophosphate to generate lithium ethylenesulfonate difluorophosphate triethylamine salt, and the coordination reaction temperature is controlled at 25-105 DEG C, and then inert organic solvent is added for crystallization to obtain lithium ethylenesulfonate difluorophosphate triethylamine salt product.
[0007] The above reaction process is shown as follows: .
[0008] Further, the aforementioned preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, wherein in the first step, the molar ratio of the chlorination reagent to sodium hydroxyethyl sulfonate is 2-4.
[0009] Further, the aforementioned preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, wherein in the first step, the molar ratio of triethylamine to sodium hydroxyethyl sulfonate is 2-3.
[0010] Further, the aforementioned preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, wherein in the first step, the mass ratio of the chlorination reaction solvent to sodium hydroxyethyl sulfonate is 3-8.
[0011] Further, the aforementioned preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, wherein in the second step, the polar organic solvent is selected from one of ethanol, acetonitrile, tetrahydrofuran, dimethylformamide, acetone and propylene carbonate; and the mass ratio of the polar organic solvent to lithium difluorophosphate is 5-10.
[0012] Further, the aforementioned preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, wherein in the second step, the inert organic solvent used for crystallization is selected from one of n-hexane, dichloromethane and toluene; and the mass ratio of the inert organic solvent to the polar organic solvent is 1-3.
[0013] Further, the aforementioned preparation method of lithium ethylenesulfonate difluorophosphate triethylamine salt, wherein in the first step, the chlorination reaction time is controlled at 6-12 h.
[0014] Furthermore, in the aforementioned method for preparing lithium difluorophosphate triethylamine salt of ethylene sulfonate, the coordination reaction time in the second step is controlled at 2-8 hours.
[0015] The advantages of this invention are: low raw material cost, simple operation, few by-products, high yield, high product purity, and it is conducive to industrial production. Attached Figure Description
[0016] Figure 1 This is the 1H NMR spectrum of the product in Example 1.
[0017] Figure 2 This is the carbon NMR spectrum of the product in Example 1. Detailed Implementation
[0018] The preparation method of lithium difluorophosphate triethylamine salt of vinylsulfonate according to the present invention will be described in detail below through specific embodiments.
[0019] Example 1: 148g of sodium hydroxyethyl sulfonate, 740g of toluene, and 357g of thionyl chloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 80°C and reacted for 8 hours before the reaction was stopped.
[0020] After cooling the reaction solution to room temperature, the solvent was evaporated, and the product was hydrolyzed to sulfonic acid. 253g of triethylamine was added dropwise, the solvent was evaporated again, and 1452g of propylene carbonate and 242g of lithium difluorophosphate were added. The mixture was heated to 75℃ and reacted for 5 hours. The reaction was then stopped, cooled to room temperature, and 2904g of n-hexane was added dropwise with stirring to induce crystallization. The crystals were filtered, and the filter cake was dried to obtain 411g of the final product: lithium difluorophosphate triethylamine salt of ethylene sulfonate. Its 1H NMR spectrum... Figure 1 As shown, 1 H NMR(400MHz,D2O)δ6.64 (1H, dd, J = 8 Hz), 5.97 (1H, d, J =8 Hz), 5.57 (1H, d, J = 8 Hz), 3.24 (6H, q, J = 4 Hz), 1.34 (9H, t, J = 4Hz); its carbon NMR spectrum is shown in Figure 2 As shown, 13 C NMR (100MHz, CDCl3) δ 141.07, 120.20, 47.90, 9.20. The product purity is 99.78%, and the calculated molar yield is 96.71%.
[0021] Example 2: 148g of sodium hydroxyethyl sulfonate, 1184g of toluene, and 306g of phosphorus oxychloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 100°C and reacted for 6 hours before the reaction was stopped.
[0022] After cooling the reaction solution to room temperature, the solvent was evaporated, and the solution was hydrolyzed to sulfonic acid. 202g of triethylamine was added dropwise, the solvent was evaporated, and 1100g of ethanol and 220g of lithium difluorophosphate were added. The mixture was heated to 105℃ and reacted for 2 hours. The reaction was then stopped, cooled to room temperature, and 3300g of toluene was added dropwise with stirring to induce crystallization. The mixture was filtered, and the filter cake was dried to obtain 386g of triethylamine difluorophosphate of ethylene sulfonate, with a purity of 99.17%. The calculated molar yield was 90.82%.
[0023] Example 3: 148g of sodium hydroxyethyl sulfonate, 1100g of acetonitrile, and 508g of oxaloyl chloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 25°C and reacted for 12 hours before the reaction was stopped.
[0024] After cooling the reaction solution to room temperature, the solvent was evaporated, and the solution was hydrolyzed to sulfonic acid. 303g of triethylamine was added dropwise, the solvent was evaporated, and 2750g of dimethylformamide and 275g of lithium difluorophosphate were added. The mixture was heated to 25°C and reacted for 8 hours. The reaction was then stopped, cooled to room temperature, and 2750g of dichloromethane was added dropwise with stirring to induce crystallization. The crystals were filtered, and the filter cake was dried to obtain 392g of triethylamine difluorophosphate of ethylene sulfonate, with a purity of 99.39%. The calculated molar yield was 92.24%.
[0025] Example 4: 148g of sodium hydroxyethyl sulfonate, 444g of toluene, and 270g of sulfonyl chloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 25°C and reacted for 12 hours before the reaction was stopped.
[0026] After cooling the reaction solution to room temperature, the solvent was evaporated, and the solution was hydrolyzed to sulfonic acid. 253g of triethylamine was added dropwise, the solvent was evaporated, and 1400g of tetrahydrofuran and 231g of lithium difluorophosphate were added. The mixture was heated to 60℃ and reacted for 4 hours. The reaction was then stopped, cooled to room temperature, and 2100g of n-hexane was added dropwise with stirring to induce crystallization. The mixture was filtered, and the filter cake was dried to obtain 376g of triethylamine difluorophosphate of ethylene sulfonate, with a purity of 99.05%. The calculated molar yield was 88.47%.
[0027] Example 5: 148g of sodium hydroxyethyl sulfonate, 600g of toluene, and 357g of thionyl chloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 65°C and reacted for 8 hours before the reaction was stopped.
[0028] After cooling the reaction solution to room temperature, the solvent was evaporated, and the solution was hydrolyzed to sulfonic acid. 223g of triethylamine was added dropwise, the solvent was evaporated, and 1300g of acetone and 264g of lithium difluorophosphate were added. The mixture was heated to 40℃ and reacted for 6 hours. The reaction was then stopped, cooled to room temperature, and 2600g of dichloromethane was added dropwise with stirring to induce crystallization. The mixture was filtered, and the filter cake was dried to obtain 395g of triethylamine difluorophosphate of ethylene sulfonate, with a purity of 99.31%. The calculated molar yield was 92.94%.
[0029] Example 6: 148g of sodium hydroxyethyl sulfonate, 1150g of dichloroethane, and 416g of phosphorus pentachloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 50°C and reacted for 10 hours before the reaction was stopped.
[0030] After cooling the reaction solution to room temperature, the solvent was evaporated, and the solution was hydrolyzed to sulfonic acid. 304g of triethylamine was added dropwise, the solvent was evaporated, and 1500g of propylene carbonate and 270g of lithium difluorophosphate were added. The mixture was heated to 65℃ and reacted for 6 hours. The reaction was then stopped, cooled to room temperature, and 3500g of toluene was added dropwise with stirring to induce crystallization. The mixture was filtered, and the filter cake was dried to obtain 389g of lithium difluorophosphate triethylamine salt of ethylene sulfonate with a purity of 99.65%. The calculated molar yield was 91.53%.
[0031] Example 7: 148g of sodium hydroxyethyl sulfonate, 900g of toluene, and 280g of phosphorus trichloride were added to a three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 90°C and reacted for 8 hours before the reaction was stopped.
[0032] After cooling the reaction solution to room temperature, the solvent was evaporated, and the solution was hydrolyzed to sulfonic acid. 290g of triethylamine was added dropwise, the solvent was evaporated, and 1450g of propylene carbonate and 242g of lithium difluorophosphate were added. The mixture was heated to 95℃ and reacted for 3 hours. The reaction was then stopped, cooled to room temperature, and 2900g of n-hexane was added dropwise with stirring to induce crystallization. The mixture was filtered, and the filter cake was dried to obtain 402g of triethylamine difluorophosphate lithium ethylene sulfonate product with a purity of 99.57%. The calculated molar yield was 94.59%.
[0033] Comparative Example 8: In an ice-water bath, 101g of triethylamine was added to a reaction flask, followed by the addition of 196g of 25wt% dilute sulfuric acid. The reaction was allowed to proceed for 0.5h, and then 520g of 25wt% sodium ethylene sulfonate aqueous solution was added. After the addition was complete, the reaction was allowed to proceed for another 0.5h. The solution was then removed by rotary evaporation, dissolved in methanol, filtered, concentrated, dissolved in dichloromethane, dried, and concentrated to obtain triethylamine ethylene sulfonate salt.
[0034] The triethylamine diethylene sulfonate salt was dissolved in 500 mL of methanol and added dropwise to a methanol solution of lithium difluorophosphate (220 g of lithium difluorophosphate and 300 mL of methanol). The mixture was heated to 60 °C and reacted for 1.5 h. After dissolving, the solution was filtered, the filtrate was concentrated, and dimethyl carbonate was added to crystallize the solution. The solution was then filtered and dried under vacuum at 60 °C for 2 h to obtain 287 g of the triethylamine difluorophosphate lithium diethylene sulfonate product with a purity of 89.37%. The calculated molar yield was 67.53%, and the contents of Na and K ions were both greater than 0.1%.
[0035] Examples 1 to 7 above show that the preparation method described in this invention yields high-yield and high-purity lithium difluorophosphate triethylamine salt. However, the experimental results of Comparative Example 8 show that its yield is significantly lower than that of Examples 1 to 7, with a significant increase in byproducts and a substantial decrease in product purity.
[0036] Therefore, the method for preparing lithium difluorophosphate triethylamine salt of ethylene sulfonate as described in this invention application uses sodium hydroxyethyl sulfonate as a starting material, which is inexpensive and readily available, effectively reducing production costs. An excess of chlorinating agent simultaneously chlorinates the hydroxyl groups and sodium sulfonate. An excess of triethylamine neutralizes the sulfonic acid to form a salt, while an elimination reaction generates vinyl groups. This multi-site tandem reaction simplifies the synthesis steps and greatly improves synthesis efficiency. The entire preparation method has low raw material costs, simple operation, few byproducts, high yield, and high product purity, which is beneficial for industrial production.
Claims
1. A method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate, characterized in that: Includes the following steps: I. Sodium hydroxyethyl sulfonate is chlorinated with an excess chlorinating agent in a chlorination reaction solvent to obtain chloroethane sulfonyl chloride, which is then hydrolyzed to chloroethane sulfonic acid. This chloroethane sulfonic acid then undergoes an elimination and acid-base neutralization reaction with excess triethylamine to obtain triethylamine vinyl sulfonate. The chlorinating agent is selected from one of thionyl chloride, oxaloyl chloride, sulfonyl chloride, phosphorus oxychloride, phosphorus trichloride, and phosphorus pentachloride. The chlorination reaction solvent is selected from one of toluene, dichloroethane, and acetonitrile. The chlorination reaction temperature is controlled at 25℃~100℃. II. In a polar organic solvent, triethylamine vinyl sulfonate undergoes a coordination reaction with lithium difluorophosphate to generate lithium difluorophosphate triethylamine vinyl sulfonate. The coordination reaction temperature is controlled at 25℃~105℃. Crystallization with an inert organic solvent yields the finished product, lithium difluorophosphate triethylamine vinyl sulfonate.
2. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the first step, the molar ratio of chlorination reagent to sodium hydroxyethyl sulfonate is 2-4.
3. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the first step, the molar ratio of triethylamine to sodium hydroxyethyl sulfonate is 2 to 3.
4. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the first step, the mass ratio of the chlorination reaction solvent to sodium hydroxyethyl sulfonate is 3 to 8.
5. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the second step, the polar organic solvent is selected from one of ethanol, acetonitrile, tetrahydrofuran, dimethylformamide, acetone, and propylene carbonate; the mass ratio of the polar organic solvent to lithium difluorophosphate is 5 to 10.
6. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the second step, the inert organic solvent used for crystallization is selected from one of n-hexane, dichloromethane, and toluene; the mass ratio of the inert organic solvent to the polar organic solvent is 1 to 3.
7. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the first step, the chlorination reaction time is controlled at 6~12h.
8. The method for preparing lithium difluorophosphate triethylamine salt of vinylsulfonate according to claim 1, characterized in that: In the second step, the coordination reaction time is controlled between 2 and 8 hours.