Method for drying and purifying LiFSI
The present invention relates to a method for drying and purifying a lithium bis(fluorosulfonyl)imide salt in solution in an organic solvent S1, said method comprising the following steps: a) adding deionised water to dissolve and extract the lithium bis(fluorosulfonyl)imide salt, forming an aqueous solution of said salt; b) extracting the lithium bis(fluorosulfonyl)imide salt from said aqueous solution, using an organic solvent S2, said step being repeated at least once; c) concentrating the lithium bis(fluorosulfonyl)imide salt by evaporating said organic solvent S2 and the water, in a short-path thin-film evaporator, under the following conditions: temperature of 30° C. to 95° C., pressure of 10 −3 mbar abs to 5 mbar abs, residence time no longer than 15 min; and d) optionally crystallising the lithium bis(fluorosulfonyl)imide salt. The present invention likewise relates to a composition made of lithium bis(fluorosulfonyl)imide salt, and the uses thereof in Li-ion batteries.
1. A composition C comprising:
at least 99.80% by weight of lithium bis(fluorosulfonyl)imide 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 composition C; and
a mass content of sulfate ions of less than or equal to 100 ppm by mass relative to the total mass of composition C.
2. The composition C as claimed in claim 1 , comprising a mass content of sulfate ions of between 2 and 100 ppm by mass relative to the total mass of said composition C.
3. The composition C as claimed in claim 1 , comprising:
a mass content of water of between 5 and 45 ppm by mass relative to the total mass of said composition C;
a mass content of sulfate ions of less than or equal to 100 ppm relative to the total mass of said composition C;
a mass content of Cl − of less than or equal to 50 ppm by mass relative to the total mass of said composition C.
4. The composition C as claimed in claim 1 , wherein the sum of the water content and of the sulfate content is less than or equal to 100 ppm.
5. A Li-ion battery comprising a composition C as claimed in claim 1 .
6. The Li-ion battery as claimed in claim 5 , wherein the Li-ion battery is in a mobile device, an electric vehicle, or a renewable energy generation system.
7. The composition C as claimed in claim 1 , comprising at least 99.85% by weight of lithium bis(fluorosulfonyl)imide salt relative to the total weight of said composition C.
8. The composition C as claimed in claim 1 , comprising at least 99.90% by weight of lithium bis(fluorosulfonyl)imide salt relative to the total weight of said composition C.
9. The composition C as claimed in claim 1 , comprising at least 99.95% by weight of lithium bis(fluorosulfonyl)imide salt relative to the total weight of said composition C.
10. The composition C as claimed in claim 1 , comprising between 5 and 40 ppm by mass of water relative to the total mass of composition C.
11. The composition C as claimed in claim 1 , comprising a mass content of sulfate ions of less than or equal to 90 ppm by mass relative to the total mass of composition C.
12. The composition C as claimed in claim 1 , comprising a mass content of sulfate ions of less than or equal to 50 ppm by mass relative to the total mass of composition C.
13. The composition C as claimed in claim 1 , comprising a mass content of sulfate ions of less than or equal to 10 ppm by mass relative to the total mass of composition C.
14. The composition C as claimed in claim 1 , comprising a mass content of Cl − of less than or equal to 40 ppm by mass relative to the total mass of said composition C.
15. The composition C as claimed in claim 1 , comprising a mass content of Cl − of less than or equal to 25 ppm by mass relative to the total mass of said composition C.
16. The composition C as claimed in claim 1 , wherein the sum of the water content and of the sulfate content is between 5 and 90 ppm.
17. The composition C as claimed in claim 1 , wherein the sum of the water content and of the sulfate content is between 10 and 60 ppm.
18. The composition C as claimed in claim 1 , comprising:
at least 99.90% by weight of lithium bis(fluorosulfonyl)imide salt relative to the total weight of said composition C;
between 5 and 40 ppm by mass of water relative to the total mass of composition C;
a mass content of sulfate ions of less than or equal to 50 ppm by mass relative to the total mass of composition C; and
a mass content of Cl − of less than or equal to 45 ppm by mass relative to the total mass of said composition C.
19. The composition C as claimed in claim 18 , wherein the sum of the water content and of the sulfate content is between 10 and 60 ppm.
20. The composition C as claimed in claim 1 , comprising:
at least 99.95% by weight of lithium bis(fluorosulfonyl)imide salt relative to the total weight of said composition C;
between 5 and 40 ppm by mass of water relative to the total mass of composition C;
a mass content of sulfate ions of less than or equal to 10 ppm by mass relative to the total mass of composition C; and
a mass content of Cl − of less than or equal to 25 ppm by mass relative to the total mass of said composition C.