Method for drying and purifying lithium bis(fluorosulfonyl)imide salt
AssigneeArkema France
InventorsGrégory Schmidt, Rémy Teissier
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Abstract
A method for drying and purifying a lithium bis(fluorosulfonyl)imide salt. Also, a method for producing a lithium bis(fluorosulfonyl)imide salt which is then dried and purified by the method. Further, a composition containing lithium bis(fluorosulfonyl)imide salt having a water content by mass of between 5 and 45 ppm. And, the use of the composition C in Li-ion batteries.
Claims19
A process for drying and purifying a lithium bis(fluorosulfonyl)imide salt in solution in an organic solvent S1, said process comprising the following steps:
- a) addition of deionized water to dissolve and extract the lithium bis(fluorosulfonyl)imide salt, forming an aqueous solution of said salt;
- a′) optional concentration of said aqueous solution;
- b) extraction of the lithium bis(fluorosulfonyl)imide salt from said aqueous solution, with an organic solvent S2 forming an azeotropic mixture with water, this step being repeated at least once;
- c) concentration of said lithium bis(fluorosulfonyl)imide salt by evaporation of said organic solvent S2 and of the water, and
- d) optionally, crystallization of the lithium bis(fluorosulfonyl)imide salt.
The process as claimed, in which, during step d), the lithium bis(fluorosulfonyl)imide salt is crystallized under cold conditions at a temperature of less than or equal to 25° C., optionally in an organic solvent S3 chosen from chlorinated solvents, and aromatic solvents, said salt optionally being recovered by filtration.
A composition C comprising:
- at least 99.80% by weight of lithium bis(fluorosulfonyl)imide (LiFSI) salt relative to the total weight of said composition C;
- between 5 ppm and 45 ppm by mass of water relative to the total mass of said composition C.
Dependencies are inferred from the claim text.