CN-117208864-B - Method for purifying dihalosulfonyl imide acid and application thereof

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a method for purifying dihalosulfonyl imide acid and application thereof. The method for purifying the dihalosulfonyl imide acid comprises the steps of adding a medium-polarity solvent into a dihalosulfonyl imide acid crude product to purify the dihalosulfonyl imide acid crude product to obtain a mixture containing the purified dihalosulfonyl imide acid, adding a low-polarity solvent into the mixture containing the purified dihalosulfonyl imide acid, standing for crystallization at the temperature of less than or equal to 5 ℃, and carrying out solid-liquid separation after crystallization is completed to obtain the purified dihalosulfonyl imide acid, wherein the polarity index of the medium-polarity solvent is 2-6, and the polarity index of the low-polarity solvent is less than or equal to 1. The method can simultaneously improve the purity and the yield of the dihalosulfonyl imide acid.

Inventors

• WANG SUPING
• LIU SHIQI
• YANG JIAOJIAO
• WANG SHUNFEI
• LV FEI
• SHANG XIAOYAN

Assignees

• 湖北万润新能源科技股份有限公司

Dates

Publication Date

20260512

Application Date

20230922

Claims (6)

1. 1. A process for purifying dihalosulfonylidine acid comprising the steps of: adding a medium-polarity solvent into the crude dihalosulfonyl imide acid product for purification to obtain a mixture containing the purified dihalosulfonyl imide acid; Adding a low-polarity solvent into the mixture containing the purified dihalosulfonyl imide acid, standing at the temperature of-30-5 ℃ for crystallization, and carrying out solid-liquid separation after the crystallization is completed to obtain the purified dihalosulfonyl imide acid; wherein the medium polarity solvent comprises at least one of dichloromethane, isobutanol, acetone, pyridine, paraxylene, ethyl acetate, chloroform, diethyl ether and toluene; The low polarity solvent comprises at least one of hexane, cyclohexane, petroleum ether, pentane, trimethylpentane, butyl chloride, cyclopentane, heptane and carbon disulfide; The molar ratio of the dihalosulfonyl imide acid to the medium-polarity solvent is 1:0.1-1; The molar ratio of the dihalosulfonyl imide acid to the low-polarity solvent is 1:0.8-4; In the process of adding the medium polarity solvent into the crude dihalosulfonyl imidic acid, the temperature of a mixed system is 30-60 ℃; The purity of the purified dihalosulfonyl imide acid is more than or equal to 99 percent; The content of HSO 3 - in the purified dihalosulfonyl imide acid is less than or equal to 50ppm; The content of Cl - in the purified dihalosulfonyl imide acid is less than or equal to 50ppm.
2. 2. The method for purifying dihalosulfonylimide acid according to claim 1, wherein the standing crystallization time is 24 to 48 hours.
3. 3. The method for purifying dihalosulfonyl imide acid according to claim 1, wherein the time for mixing the crude dihalosulfonyl imide acid with the medium-polarity solvent is 3 to 12 hours.
4. 4. The method for purifying a dihalosulfonyl imide acid according to claim 1, wherein the dihalosulfonyl imide acid includes at least one of a bischlorosulfonyl imide acid and a bisfluorosulfonyl imide acid.
5. 5. The method for purifying a dihalosulfonylimide acid according to claim 4, wherein at least one of the following features (1) to (3) is contained: (1) The difluoro sulfimide acid is mainly prepared by reacting dichloro sulfimide acid with a fluorine source under the action of a catalyst; (2) The dichlor sulfimide acid is mainly prepared from chlorosulfonic acid, sulfamic acid and thionyl chloride; (3) The dichlorsulfoimide acid is mainly prepared by the reaction of chlorosulfonic acid and chlorosulfonyl isocyanate under the action of a catalyst.
6. 6. A method for producing lithium bis (fluorosulfonyl) imide, comprising the method for purifying bis (halosulfonyl) imide according to any one of claims 1 to 5.

Description

Method for purifying dihalosulfonyl imide acid and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a method for purifying dihalosulfonyl imide acid and application thereof, and more particularly relates to a method for purifying dihalosulfonyl imide acid, a method for preparing lithium difluorosulfimide, an electrolyte and a lithium ion battery. Background Dihalo (chloro/fluoro) sulfonylimide acid is an important chemical intermediate that can be used in the preparation of lewis acid catalysts, ion transfer agents, organic compound synthesis, electrolytes, and the like. Particularly in the field of lithium ion battery electrolyte salt synthesis, along with the gradual application of lithium bis (fluorosulfonyl imide) (LIFSI) as an electrolyte lithium salt in an electrolyte, the preparation of high-purity lithium bis (fluorosulfonyl imide) becomes a research hot spot. In the current synthesis route of lithium bis (fluorosulfonyl) imide, the preparation of bis (chlorosulfonyl) imide and LIFSI through fluorination and lithiation processes are the most suitable technological route for industrial production. To increase the purity of LIFSI product, the important intermediate dichloro/fluoro-sulfinamide acid is purified. For example, the distillation method is adopted to purify the dichlorsulfonylimide acid in the prior literature, but the purification method has long duration and high energy consumption in the whole process and is not suitable for industrial production. In another prior art, the reaction mixture is heated to a viscous consistency and turned to a light brown color, and then the reaction mixture is fractionated under vacuum, and the main fraction is collected in the range of 95-110 ℃ per 650Pa, however, in this process, the fraction collection temperature is narrow, and chlorosulfonic acid with extremely high volatility is very likely to be mixed, so that higher purity is difficult to achieve. In view of this, the present invention has been made. Disclosure of Invention The first aim of the invention is to provide a method for purifying dihalosulfonyl imide acid, which adopts a medium polarity solvent to extract unreacted raw materials, and promotes crystallization of a target product at low temperature through a low polarity solvent, so that the purification efficiency of the dihalosulfonyl imide acid can be remarkably improved, the purification process is simple and easy to implement, and the purity of the obtained dihalosulfonyl imide acid is high. The second object of the present invention is to provide a method for producing lithium difluorosulfimide, which can improve the purity of the produced lithium difluorosulfimide by purifying dihalosulfonyl imide acid. The third object of the present invention is to provide an electrolyte, which is prepared from high-purity lithium bis (fluorosulfonyl) imide, so as to be beneficial to improving the electrochemical performance of a lithium ion battery prepared from the electrolyte. A fourth object of the present invention is to provide a lithium ion battery that is excellent in electrochemical performance. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: The invention provides a method for purifying dihalosulfonyl imide acid, which comprises the following steps: adding a medium-polarity solvent into the crude dihalosulfonyl imide acid product for purification to obtain a mixture containing the purified dihalosulfonyl imide acid; adding a low-polarity solvent into the mixture containing the purified dihalosulfonyl imide acid, standing at the temperature of less than or equal to 5 ℃ for crystallization, and carrying out solid-liquid separation after the crystallization is completed to obtain the purified dihalosulfonyl imide acid; wherein the polarity index of the medium polarity solvent is 2-6; the polarity index of the low-polarity solvent is less than or equal to 1. The invention purifies the dihalosulfonyl imide acid by adopting different polar solvent compounding methods, so that the double effects of impurity removal and crystallization of a target product can be realized, the purification efficiency of the product is improved, and the purity of the product is obviously improved. The invention also provides a preparation method of the lithium bis (fluorosulfonyl) imide, which comprises a purification method of the bis (halosulfonyl) imide acid. The method can obviously improve the purity of the lithium bis (fluorosulfonyl) imide. The invention also provides an electrolyte, which comprises the lithium bis (fluorosulfonyl) imide prepared by the preparation method of the lithium bis (fluorosulfonyl) imide. The electrolyte adopts high-purity lithium bis (fluorosulfonyl) imide, so that the impurity content is low, and the electrochemical performance of a lithium ion battery prepared from the electrolyte ca