Preparation method of difluorosulfimide salt

Abstract

The invention discloses a preparation method of difluorosulfimide salt. The preparation method comprises the following steps: (1) adding dichlorosulfimide and a nitrogen-containing hydrogen fluoride complex which are used as reaction raw materials into an organic solvent for reaction at 0-100 DEG C, and after reaction, distilling to remove the organic solvent to obtain a difluorosulfimide and nitrogen-containing ion compound; (2) adding the ion compound obtained in the step (1) into a water solution of metal alkali or salt, neutralizing until the solution is neutral, distilling, drying, re-crystallizing by using the organic solvent, and purifying to obtain difluorosulfimide salt. According to the preparation method, the nitrogen-containing hydrogen fluoride complex is adopted as a fluorating agent, so that the whole reaction is carried out in a homogeneous system, the fluorating reaction is relatively safe, the efficiency is relatively high, and the product yield is more than 98%; a process route is simple, the yield is high, and the production cost is relatively low.

Description

technical field [0001] The invention relates to a method for preparing an electrolyte electrolyte difluorosulfonimide salt. Background technique [0002] Difluorosulfonimide salts are mainly used in lithium ion electrolytes of lithium batteries. Difluorosulfonimide salts can be used as electrolyte additives for lithium ion batteries to improve the cycle performance of lithium ion batteries, and can also be used as electrolytes for primary batteries. ; It can also be used as a polymerization catalyst, and can also be used as an antistatic agent in the industrial field. [0003] Now studies have shown that difluorosulfonyl imide salts can be used in the electrolyte of rechargeable lithium batteries, which can effectively improve the conductivity, and PC can form a stable SEI film on the surface of graphite negative electrodes, making a contribution to solving the problem of low-temperature use of batteries . with LiPF 6 Compared with it, it is superior in many aspects such ...

AI Technical Summary

Problems solved by technology

There is following shortcoming in said method: (1) Potassium fluoride and dichlorosulfonimide synthesize difluorosulfonimide potassium in organic solvent, and contain one chloro one fluorosulfonimide, fluorosulfonimide in the product Impurities such as amides are difficult to separate and the yield is low; (2) the reaction time is long and it is difficult to obtain solid salt; React with a metal base or salt to give the corresponding difluorosulfonimide salt

AsF used in this route 3 It is a toxic reagent, which seriously pollutes the environment and cannot be prepared on a large scale

Using SbF 3 During fluorination, the by-products are difficult to separate. Zhou Zhibin and others have optimized this type of process, and proposed that the corresponding potassium salt of bisfluorosulfonyl imide can be prepared by directly adding potassium carbonate without separating the intermediate product. Although this route is better Solve the difficult separation of by-product SbCl 3 problem, but the process steps are more cumbersome

Compared with the above two-step reaction to realize HN[SO 2 Cl] 2 Converted to the route of potassium salt of bisfluorosulfonyl imide, HN[SO 2 Cl] 2 Directly react with excess potassium fluoride (KF) etc. in an organic solvent to prepare bisfluorosulfonimide potassium salt [KN(SO 2 F) 2 , hereinafter referred to as KFSI] process is relatively simple, but this route produces a large amount of corrosive and highly toxic gas HF, and the excess reactant KF mixed with the product KFSI is easy to agglomerate

On the other hand, in the lithium salt of bisfluorosulfonimide, which is a product obtained by reacting lithium salts (lithium perchlorate, etc.) with the above-mentioned potassium salt of bisfluorosulfonimide, etc. Difficult to guarantee purity due to the presence of small amounts of lithium salt impurities