Method for producing a fluorine-containing sulfonylimides salt

A fluorine-containing sulfonylimide ammonium salt such as N, N-di (fluorosulfonyl) imidoammonium salt and an alkali metal hydroxide such as lithium hydroxide, potassium hydroxide or sodium hydroxide are reduced to about 40 ° C. under reduced pressure. Fluorine-containing sulfonyl such as N, N-di (fluorosulfonyl) imide lithium salt, N, N-di (fluorosulfonyl) imide potassium salt, N, N-di (fluorosulfonyl) imide sodium salt by reacting at low temperature An imide alkali metal salt is obtained.