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.