Preparation method for lithium bis(fluorosulfonyl)imide including multiple ammonia source additions, electrolytic solution and secondary battery

Abstract

A method for preparing lithium bis(fluorosulfonyl)imide, including (1) adding an organic solvent and an absorbent A to a reaction kettle, then adding part of an ammonia source, and finally adding SOXand a remaining ammonia source simultaneously for reaction, to obtain a solution of a salt (SOF—NH—SOF)·A containing bis(fluorosulfonyl)imide and the absorbent A, where in the SOX, X is independently fluorine or chlorine; (2) performing filtration, concentration and washing on the solution obtained in step (1) to obtain a purified salt (SOF—NH—SOF)·A of the bis(fluorosulfonyl)imide and the absorbent A; (3) adding a lithium source to the purified salt (SOF—NH—SOF)·A of the bis(fluorosulfonyl)imide and the absorbent A obtained in step (2) for reaction to obtain a solution containing lithium bis(fluorosulfonyl)imide; and (4) performing dehydration, concentration, crystallization with a non-aqueous poor solvent, and drying on the solution obtained in step (3) to obtain the lithium bis(fluorosulfonyl)imide is described.