METHOD FOR PREPARING HIGH-PURITY BISFLUOROSULFONYLIMIDE SALT

The present invention relates to the technical field of additives to an electrolytic solution of salt batteries; in particular, the present invention relates to a method for preparing a high-purity bisfluorosulfonylimide salt. The preparation raw materials include at least bisfluorosulfonylimide, and Mn X; wherein M is selected from any one of Li, Na, K, Rb and Cs, X is an anion including at least one element of B, O, N, P and Si, and n≥2. In the method for preparing a bisfluorosulfonylimide salt provided by the present disclosure, a conversion rate for a target product is high, there is only a single reaction product with almost no side reactions, and the purity of the product is high; during the implementation, there is substantially no generation of the "three wastes", and the byproducts and solvent can be recycled.