JP-2026514265-A - Method for preparing fluoroethylene carbonate

Abstract

This invention relates to the technical field of lithium-ion battery electrolyte additive synthesis and provides a method for preparing fluoroethylene carbonate. The invention involves mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate. By adding the polymerization inhibitor and catalyst simultaneously, the invention avoids the occurrence of side reactions such as polymerization of materials, while increasing the reaction rate, improving the conversion rate and product yield. The invention uses liquid hydrogen fluoride as the fluorination reagent, resulting in low cost, ease of use, and convenience for continuous production. The invention utilizes a benzotrifluoride compound as the solvent, effectively utilizing the remaining hydrogen fluoride, enabling efficient resource utilization and reducing production costs. The fluorination reaction of this invention can be carried out in a microchannel reactor, enabling continuous automated production. Therefore, the preparation method provided by this invention is efficient, economical, green, and environmentally friendly, offering broad prospects. [Selection Diagram] Figure 2

Inventors

• 李恵躍
• 晏金華
• 陳応恵
• 郭▲しん▼意
• 袁芸晟
• 斉偉敏

Assignees

• 景徳鎮富祥生命科技有限公司
• 江西富祥薬業股▲ふん▼有限公司

Dates

Publication Date

20260508

Application Date

20240307

Priority Date

20240124

Claims (16)

1. A method for preparing fluoroethylene carbonate, A method for preparing fluoroethylene carbonate, comprising the step of mixing chloroethylene carbonate, a polymerization inhibitor, a catalyst, and liquid hydrogen fluoride to carry out a fluorination reaction to obtain fluoroethylene carbonate, wherein the catalyst comprises one or more of metal fluorides, metal chlorides, and tetrabutylammonium fluoride, and the polymerization inhibitor comprises one or more of amine-based polymerization inhibitors, phenol-based polymerization inhibitors, and piperidinyl nitrooxide radical-based polymerization inhibitors.
2. A solvent is also added during the mixing process, and the solvent is a benzotrifluoride compound, the structural formula of which is shown in formula I. Equation I, In formula I, n is an integer from 0 to 5, and R is one or more of alkyl groups, phenyl groups, and halogens. The preparation method according to claim 1, characterized in that the molar ratio of chloroethylene carbonate to solvent is 1:(0.2 to 2).
3. The preparation method according to claim 2, characterized in that the benzotrifluoride compound is benzotrifluoride or p-chlorobenzotrifluoride.
4. The preparation method according to claim 2, characterized in that the fluorination reaction is carried out in an autoclave.
5. The fluorination reaction involves adding chloroethylene carbonate, a solvent, a catalyst, a polymerization inhibitor, and liquid hydrogen fluoride to an autoclave, and then heating the mixture to carry out the fluorination reaction under constant temperature and pressure conditions. The preparation method according to claim 4, characterized in that, in the fluorination reaction process, hydrogen chloride gas generated during the reaction is discharged, the discharged hydrogen chloride gas is absorbed with water to prepare by-product hydrochloric acid, the pressure of the fluorination reaction is controlled by controlling the discharge of hydrogen chloride gas, and in the fluorination reaction process, the generated gaseous hydrogen fluoride and gaseous solvent are collected after condensation and then returned to the autoclave.
6. The process includes: mixing the resulting reaction solution with a benzotrichloride compound after the fluorination reaction is completed; reacting the benzotrichloride compound with the remaining hydrogen fluoride in the reaction solution to obtain a mixed reaction solution of fluoroethylene carbonate and a benzotrifluoride compound; distilling and desolvating the mixed reaction solution to obtain a concentrated solution and a benzotrifluoride compound, respectively; recycling the benzotrifluoride compound obtained by distillation and desolvation; and sequentially performing rectification and melt crystallization on the concentrated solution to obtain a fluoroethylene carbonate product. The structure of the aforementioned benzotrichloride compound is shown in formula II. Formula II, The preparation method according to claim 5, characterized in that, in formula II, n is an integer from 0 to 5, and R is one or more of an alkyl group, a phenyl group, and a halogen.
7. The preparation method according to claim 1 or 2, characterized in that the fluorination reaction is carried out in a microchannel reactor.
8. The fluorination reaction described above is The process involves mixing chloroethylene carbonate, a catalyst, and a polymerization inhibitor to obtain a mixture, or mixing chloroethylene carbonate, a catalyst, a polymerization inhibitor, and a solvent to obtain a mixture. The preparation method according to claim 7, characterized by comprising introducing the aforementioned mixture and liquid hydrogen fluoride into a microchannel reactor to carry out a fluorination reaction.
9. The preparation method according to claim 8, characterized in that the flow rate ratio of chloroethylene carbonate to liquid hydrogen fluoride in the aforementioned mixture is 6:(1-5).
10. The preparation method according to claim 8, further comprising: separating the gas-liquid mixture after the fluorination reaction to obtain a reaction solution and a mixed gas containing hydrogen fluoride and hydrogen chloride; condensing the mixed gas to recover hydrogen fluoride and absorbing the remaining hydrogen chloride with water to prepare hydrochloric acid.
11. The apparatus used in the fluorination reaction further includes a liquid hydrogen fluoride storage tank (1), a mixed liquid storage tank (2), a gas-liquid separator (4), a condenser (5), a reaction liquid receiving tank (6), and a liquid hydrogen fluoride recovery tank (7). The outlet of the liquid hydrogen fluoride storage tank (1) and the outlet of the mixed liquid storage tank (2) are connected to the inlet of the microchannel reactor (3). The inlet of the gas-liquid separator (4) is in communication with the outlet of the microchannel reactor (3), The inlet of the condenser (5) is connected to the gas outlet of the gas-liquid separator (4), The inlet of the reaction liquid receiving tank (6) is connected to the liquid outlet of the gas-liquid separator (4), The preparation method according to claim 7, characterized in that the inlet of the liquid hydrogen fluoride recovery tank (7) is connected to the liquid outlet of the condenser (5).
12. The preparation method according to claim 1, characterized in that the temperature of the fluorination reaction is 30°C to 80°C and the pressure is 0.1 to 1.5 MPa.
13. The polymerization inhibitor comprises one or more of phenothiazine, polymerization inhibitor 701, p-tert-butylcatechol, hydroquinone, diphenylamine, and polymerization inhibitor 705. The molar ratio of the chloroethylene carbonate to the polymerization inhibitor is 1:(0.0001 to 0.001). The preparation method according to claim 1, characterized in that the molar ratio of chloroethylene carbonate to liquid hydrogen fluoride is 1:(1 to 5).
14. The preparation method according to claim 13, characterized in that the catalyst comprises one or more of potassium fluoride, ferric chloride, antimony trichloride, tungsten hexachloride, antimony pentachloride, tin tetrachloride, titanium tetrachloride, and tetrabutylammonium fluoride, and the molar ratio of the chloroethylene carbonate to the catalyst is 1:(0.001 to 0.01).
15. The preparation method according to claim 14, characterized in that the catalyst is titanium tetrachloride and tungsten hexachloride, with a molar ratio of titanium tetrachloride to tungsten hexachloride of (1-5):1, or the catalyst is tungsten hexachloride and tin tetrachloride, with a molar ratio of tungsten hexachloride to tin tetrachloride of 1:(1-5).
16. The preparation method according to claim 6, characterized in that the rectification vessel temperature is 90°C to 110°C, the top temperature is 60°C to 80°C, the pressure is 15 mmHg or less, and the melt crystallization includes lowering the temperature of the product collected after rectification to 18°C to 20°C, allowing it to crystallize for 10 to 16 hours, then releasing the uncrystallized material, and raising the temperature of the remaining crystallized material to 35°C to 40°C to melt it, thereby obtaining a purified fluoroethylene carbonate product.

Description

This application claims priority to the Chinese patent application filed with the China National Intellectual Property Office on January 24, 2024, with application number CN202410101101.1, and title of invention "Method for Preparing Fluoroethylene Carbonate," all of which are incorporated herein by reference. This invention relates to the technical field of lithium-ion battery electrolyte additive synthesis, and more particularly to a method for preparing fluoroethylene carbonate. A lithium-ion battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte is called the "blood" of the lithium-ion battery and plays a role in conducting electrons between the positive and negative electrodes. The manufacturing cost of the electrolyte accounts for 14% of the total cost of a lithium battery, making it the most expensive component, in addition to the positive electrode material. The electrolyte is prepared by mixing raw materials such as solvent, solute (i.e., lithium salt), and additives in specific proportions. Generally, the solvent accounts for 80-90%, the lithium salt for about 8%, and the additives for 5-10%. In terms of manufacturing costs, the solute is the most expensive component, accounting for nearly 50%, followed by the solvent for about 30% and the additives for about 10%. There are many types of additives, and their roles vary. For example, they improve conductivity, overcharge safety performance, storage performance, flame retardancy, and stability. Different lithium-ion battery manufacturers have different requirements for battery applications and performance, and accordingly, the emphasis of additive selection changes. The importance of additives becomes more pronounced as the requirements for battery performance increase. Fluoroethylene carbonate is an organic film-forming additive and overcharge protection additive for lithium-ion battery electrolytes. It possesses excellent high and low temperature performance and anti-swelling properties, and can improve the capacity and cycle life of lithium-ion batteries. Currently, the main methods for producing fluoroethylene carbonate are as follows: Patent US6010806 discloses a method for reacting dimethyl carbonate and 3,3,3-trifluoro-1,2-propylene oxide in the presence of sodium bicarbonate, but the raw materials used in such a method are expensive, the reaction time is long, and it is unfavorable for industrial production (Patent Document 1). Patent CN108250176A provides a high-speed continuous-flow synthesis process for fluoroethylene carbonate, in which a mixed gas of F2 / N2 reacts with ethylene carbonate, but F2 is highly toxic, highly reactive, easily uncontrollable, highly dangerous, produces many by-product impurities, is difficult to separate and purify, and has high production costs (Patent Document 2). Patent WO98115024 describes a method for reacting chloroethylene carbonate with potassium fluoride as raw materials. This method is a relatively mature synthesis method used in the Chinese domestic industry. However, this reaction is heterogeneous, time-consuming, has a low conversion rate, requires high particle size and activity for solid potassium fluoride, is expensive, and using large quantities of solid potassium fluoride increases labor intensity, making automation difficult. Furthermore, it generates large amounts of mixed solid waste of potassium chloride and potassium fluoride, resulting in high costs for waste liquid, waste gas, and solid waste (Patent Document 3). Patent CN101774923B discloses a method for preparing fluoroethylene carbonate. This method involves a substitution reaction between chloroethylene carbonate and a fluorinating agent in the presence of an organic solvent and an acid binder to produce fluoroethylene carbonate. Because this method uses a solvent, it is expensive, the post-processing steps are complicated, and the yield is not high, at approximately 85% (Patent Document 4). Patents CN105968083A and CN114874179A disclose a method for preparing fluoroethylene carbonate. In this method, fluoroethylene carbonate is prepared using a microchannel with hydrogen fluoride as the fluorine source. Repeated experiments have shown that the actual conversion rate and product yield of this method are very limited and do not meet the requirements for industrial use (Patent Documents 5 and 6). Patent CN116178333A discloses a method for preparing fluoroethylene carbonate using chloroethylene carbonate as a raw material, hydrogen fluoride as the fluorine source, and a mixture of SbCl₅ and MoCl₅ in a certain proportion as a catalyst. However, this method produces high levels of by-product impurities, so the product yield and quality cannot be guaranteed. The yield is less than 85%, and the product purity is less than 99.5%, which does not meet the requirement of 99.95% or higher for electronic-grade lithium battery additives (Patent Document 7). Therefore, existing preparation