Fluoro-substituted ethers and compositions
Described herein are fluoro-substituted ethers of Formula (I): wherein R 1 is a fluoro-substituted C 2 -C 6 alkyl group; R 2 is a C 2 -C 6 alkyl group or a fluoro-substituted C 2 -C 6 alkyl group; each R 3 independently is H, F, methyl, or fluoro-substituted methyl; and n is 0, 1, 2, 3, or 4. The fluoro-substituted ether compounds are useful as solvents for lithium containing electrolytes in lithium batteries, particularly lithium-sulfur batteries.
1. An electrolyte composition consisting of about 0.1 M to about 1.2 M lithium salt dissolved in a nonaqueous solvent mixture consisting of dioxolane and a fluoro-substituted ether of Formula (I):
wherein R 1 is a fluoro-substituted C 2 -C 6 alkyl group; R 2 is a fluoro-substituted C 2 -C 6 alkyl group; each R 3 is H; and n is 1, 2, 3, or 4; and wherein the dioxolane and the ether of Formula (I) are present in the solvent mixture in a respective volume to volume ratio of about 1:9 to about 9:1; wherein the lithium salt is lithium bis(trifluoromethane)sulfonimidate (LiTFSI).
2. The composition of claim 1 , wherein R 1 and/or R 2 is a fluoro-substituted C 2 -C 6 alkyl group comprising at least one methylene (CH 2 ) or methine (CH) group.
3. The composition of claim 1 , wherein n is 1.
4. The composition of claim 1 , wherein n is 2.
5. The composition of claim 1 , wherein n is 3.
6. The composition of claim 1 , wherein n is 4.
7. The composition of claim 1 , wherein R 1 is CF 3 CH 2 .
8. The composition of claim 1 , wherein R 2 is CF 3 CH 2 .
9. The composition of claim 1 , wherein both R 1 and R 2 are CF 3 CH 2 .
10. The composition of claim 1 , wherein R 1 is a perfluoro C 2 -C 4 alkyl group.
11. The composition of claim 1 , wherein R 2 is a perfluoro C 2 -C 4 alkyl group.
12. The composition of claim 1 , wherein both R 1 and R 2 are perfluoro C 2 -C 4 alkyl groups.
13. The composition of claim 1 , wherein the fluoro-substituted ether of Formula (I) is selected from the group consisting of:
1,1,1,11,11,11-hexafluoro-3,6,9-trioxaundecane,
1,1,1,14,14,14-hexafluoro-3,6,9,12-tetraoxatetradecane,
1,1,1,17,17,17-hexafluoro-3,6,9,12,15-pentaoxaheptadecane, and
1,1,1,2,2,12,12,13,13,13-decafluoro-4,7,10-trioxatridecane.
14. The composition of claim 1 , wherein the ether of Formula (I) is 1,1,1,11,11,11-hexafluoro-3,6,9-trioxaundecane.
15. The composition of claim 1 , wherein the dioxolane and the ether of Formula (I) are present in the solvent mixture in a respective volume to volume ratio of about 1:3 to about 3:1.
16. The composition of claim 1 , wherein the dioxolane and the ether of Formula (I) are present in the solvent mixture in a respective volume to volume ratio of about 2:1.
17. The composition of claim 16 , wherein the ether of Formula (I) is 1,1,1,11,11,11-hexafluoro-3,6,9-trioxaundecane.
18. The composition of claim 1 , wherein the dioxolane and the ether of Formula (I) are present in the solvent mixture in a respective volume to volume ratio of about 1:1.
19. The composition of claim 18 , wherein the ether of Formula (I) is 1,1,1,11,11,11-hexafluoro-3,6,9-trioxaundecane.