Preparation method of lithium bis(trifluoromethanesulphonyl)imide salt

Abstract

The invention provides a preparation method of lithium bis(trifluoromethanesulphonyl)imide salt. The preparation method is characterized by comprising steps as follows: trifluoromethane gas is introduced into a non-polar solvent solution of lithium alkylide at low temperature under anhydrous and nitrogen protective conditions and subjected to a reaction, trifluoromethyl lithium is prepared, afterthe reaction, a lithium bis(fluorosulfonyl)imide solution is slowly dropwise added to the trifluoromethyl lithium solution at the low temperature, white solids can be separated out in a dropwise adding process, a reaction solution is filtered after dropwise addition is finished, a filtrate is evaporated under reduced pressure to be dry, white solid wet salt is obtained and subjected to vacuum drying, and lithium bis(trifluoromethanesulphonyl)imide salt is obtained. The preparation method has the advantages as follows: bis(trifluoromethanesulphonyl)imide is synthesized with a one-pot method, compared with a traditional method, a process route is greatly simplified, separating difficulty of a product and a byproduct in a reaction process is reduced, product purity is improved, so that production cost is further reduced, product performance and cost competitiveness are improved, and feasible technical support is provided for large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery electrolytes, in particular to a preparation method of bis(trifluoromethylsulfonyl)imide lithium salt. Background technique [0002] Lithium bis(trifluoromethylsulfonyl)imide (hereinafter referred to as LiTFSI), with a density of 1.334g / cm3 and a melting point of 234°C. LiTFSI has suitable electrical conductivity, high thermal stability, high electrochemical stability, and the probability of side reactions Small and other characteristics, will not produce corrosive gases such as HF, is an indispensable high-tech product in the electrolyte of lithium-ion secondary batteries. In addition to the field of lithium batteries, it also has broad application prospects in the fields of ionic liquids, antistatic and medicine. In particular, the preparation of new and new rare earth Lewis acid catalysts for the anion displacement reaction through the corresponding trifluoromethanesulfonate also h...

AI Technical Summary

Problems solved by technology

In this re-synthesis method, the reaction steps are complicated and the yield is low, so the method cannot realize industrial production;

[0005] 2. Use elemental ammonia or ammonium ions as the nitrogen source, then add trifluoromethylsulfonyl chloride to synthesize bistrifluorosulfonyl imide, and then perform lithiation reaction to obtain bis(trifluoromethylsulfonyl)imide Lithium salt, in the process of industrialized mass production, the excessive amount of ammonia is too much to promote the formation of unnecessary by-products, and elemental ammonia, such as ammonia gas, is easy to cause explosions under different temperatures and pressures, making safety problems hidden dangers;

In this method, because the raw material trifluoromethanesulfonamide used in the first step is expensive, and trifluoromethanesulfonyl fluoride is a highly corrosive gas, a high-pressure reactor of special material is required and the operation is very difficult, so this method also Unable to achieve industrial production

[0007] As mentioned above, the current bisfluorosulfonimide salt synthesis process still has disadvantages such as cumbersome process, long process, low product conversion rate, difficult separation of by-products, need for special equipment and use of highly corrosive and expensive raw materials, etc., resulting in Difficult operation, high energy consumption, environmental pollution and other defects make LiTFSI unable to realize industrial application

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