The invention relates to a process for the preparation of a bis(sulphonato)imide salt of formula:
(III) (SO3−)—N−—(SO3)3C+ (III)
where C+ represents a monovalent cation, comprising the reaction of amidosulphuric acid of formula:
(OH)—SO2—NH2 (I)
with a halosulphonic acid of formula:
(OH)—SO2—X (II)
where X represents a halogen atom, and comprising a reaction with a base which is a salt formed with the cation C+.
The invention also relates to a process for the preparation of bis(fluorosulphonyl)imide acid of formula:
F—(SO2)—NH—(SO2)—F (V)
and to a process for the preparation of lithium bis(fluorosulphonyl)imide salt of formula:
F—(SO2)—N−—(SO2)—F Li+. (VII)