Preparation method of lithium bis (fluorosulfonyl) imide

Abstract

The invention discloses a preparation method of lithium bis (fluorosulfonyl) imide. The preparation method comprises the steps of 1 by using chlorosulfonyl isocyanate and chlorosulfonic acid as reaction raw materials, dropwisely adding to react for 5 hours, and keeping the temperature to react for 10 hours to obtain bis (chlorosulfonyl) imide; 2 putting bis (chlorosulfonyl) imide serving as a reaction raw material into a tetrafluoro reaction bottle, reacting with anhydrous hydrogen fluoride under the action of a catalyst, and generating bis (fluorosulfonyl) imide after reacting for 20 hours; and 3 putting the bis (fluorosulfonyl) imide into a reaction bottle, and reacting with lithium hydroxide or lithium carbonate under the action of a catalyst to obtain a product containing lithium bis (fluorosulfonyl) imide. The preparation method disclosed by the invention is simple to operate, easy to control and small in environmental pollution, and meanwhile, inert gas is used as a reaction environment to remove water by low-temperature drying, so that the reaction of the bis (fluorosulfonyl) imide and the final product lithium bis (fluorosulfonyl) imide with water in air is avoided, the quality of the product is ensured, and the preparation method is suitable for industrial production of the lithium bis (fluorosulfonyl) imide.

Description

Technical field[0001]The invention belongs to the field of lithium bisfluorosulfonimide, and particularly relates to a method for preparing lithium bisfluorosulfonimide.Background technique[0002]Lithium bisfluorosulfonimide (LiFSI for short), as an important lithium ion battery electrolyte additive, has the characteristics of good electrochemical stability, good hydrolysis resistance, and high conductivity. It can be widely used in electrolytes, especially in In the power battery, the cycle performance and rate performance of the power battery can be improved. Lithium bisfluorosulfonimide is a new type of electrolyte lithium salt used in the electrolyte of lithium batteries. It is environmentally friendly and has good safety performance. It has the basic conditions for industrial application. Compared with the traditional lithium salt of lithium hexafluorophosphate, the lithium ions in the lithium bisfluorosulfonimide are more easily dissociated, so it has a higher electrical conduc...

AI Technical Summary

Problems solved by technology

[0004] 1) First synthesize dichlorosulfonimide, then react with ammonium fluoride to obtain bis(fluorosulfonyl)imide ammonium salt, and then perform cation exchange reaction with lithium hydroxide to obtain lithium bisfluorosulfonimide, its disadvantages The reason is that the ion exchange is difficult to carry out thoroughly, and the reaction is carried out in an aqueous system, and the water is difficult to remove completely, and the existence of water will cause the lithium salt to deteriorate and decompose when heated;

[0005] 2) Using bischlorosulfonimide to directly react with lithium fluoride to prepare lithium bisfluorosulfonimide will produce a large amount of corrosive gas HF, and the product contains hydrogen fluoride, lithium fluoride and lithium bisfluorosulfonimide at the same time. It is not easy to separate, and the HF remaining in the electrolyte will eventually cause adverse effects on the lithium battery;

[0006] 3) Lithium bisfluorosulfonyl imide is prepared by metal exchange of purified potassium bisfluorosulfonyl imide and lithium perchlorate. The residual potassium ions in the product are often high, which affects the practical application of lithium bisfluorosulfonyl imide. And there is a certain risk of explosion;

[0007] 4) Lithium bisfluorosulfonyl imide is directly reacted with lithium carbonate in ultra-low temperature aqueous solution. This method not only consumes a lot of energy, but also because lithium bisfluorosulfonyl imide has good water solubility, it is easy to extract The efficiency is very low, and there is also the problem of incomplete water removal

[0008] The purity of lithium bisfluorosulfonyl imide produced by the above-mentioned various methods is difficult to reach the battery-grade standard, and it cannot be directly applied industrially. Therefore, we propose a method for the preparation of fluoroethylene carbonate

Images