Localized high-salt-concentration electrolytes containing longer-sidechain glyme-based solvents and fluorinated diluents, and uses thereof
Localized high-salt-concentration electrolytes each containing a salt, a glyme as a solvent, and a fluorinated diluent. In some embodiments, the glyme has a chemical formula R 1 —(O—CH 2 —CH 2 ) n —O—R 2 , wherein n=1 to 4 and at least one of R 1 and R 2 is a hydrocarbon sidechain having at least 2 carbon atoms and wherein the salt is soluble in the glyme. In some embodiments, the fluorinated diluent is selected from the group consisting of a fluorinated glyme and a fluorinated ether. In some embodiments, the salt includes an alkali-metal salt. In some embodiments, the salt includes an alkali-earth-metal salt. The salt may include a perfluorinated sulfonimide salt. Electrochemical devices that include localized high-salt-concentration electrolytes of the present disclosure are also disclosed.
1. An electrolyte, consisting of:
a salt;
a solvent that is a glyme of the formula R 1 —(O—CH 2 —CH 2 ) n —O—R 2 , wherein n=1 to 4 and at least one of R 1 and R 2 is a hydrocarbon sidechain having at least 2 carbon atoms, wherein the salt is soluble in the solvent; and
a diluent selected from the group consisting of a fluorinated glyme and a fluorinated ether;
wherein:
the salt has a concentration in the electrolyte of about 0.2 M to less than 5 M;
the electrolyte has a (solvent+diluent):salt molar ratio in a range of greater than 2:1 to about 8:1; and
the electrolyte has a volumetric solvent:diluent percentage ratio of about 50:50 to about 90:10.
2. The electrolyte of claim 1 , wherein the salt comprises a lithium-based salt.
3. The electrolyte of claim 1 , wherein the concentration of the salt is in a range of about 1M to less than 5M.
4. The electrolyte of claim 1 , wherein the concentration of the salt is in a range of about 2M to about 3M.
5. The electrolyte of claim 1 , having a solvent:salt molar ratio in a range of about 2:1 to about 4:1.
6. The electrolyte of claim 1 , having a solvent:salt molar ratio in a range of about 2:1 to about 3:1.
7. The electrolyte of claim 1 , having a solvent:salt molar ratio is about 2:1.
8. The electrolyte of claim 1 , wherein R 1 =R 2 .
9. The electrolyte of claim 1 , wherein the hydrocarbon sidechain has 2 to 6 carbon atoms.
10. The electrolyte of claim 1 , wherein the salt is selected from the group consisting of lithium bis(fluorosulfonyl)imide and a salt of a molecular structure:
wherein n is equal to or greater than 0.
11. The electrolyte of claim 1 , wherein the concentration of the salt is in a range of about 0.2M to about 4M.
12. The electrolyte of claim 1 , wherein the volumetric solvent:diluent percentage ratio of the electrolyte is about 60:40 to about 80:20.
13. The electrolyte of claim 12 , wherein the concentration of the salt is in a range of about 0.2M to about 4M.
14. The electrolyte of claim 1 , wherein the concentration of the salt is at least 2M.
15. The electrolyte of claim 14 , wherein, in the solvent:diluent volumetric percentage ratio, the solvent is at least 50% and the diluent is no more than 50%.
16. The electrolyte of claim 14 , wherein, in the solvent:diluent volumetric percentage ratio, the solvent is at least 60% and the diluent is no more than 40%.
17. The electrolyte of claim 1 , wherein n=1 and each of R 1 and R 2 is an ethyl group, as in 1,2-diethoxyethane (DEE).
18. The electrolyte of claim 17 , wherein the diluent comprises a fluorinated ether.
19. The electrolyte of claim 17 , wherein the diluent comprises a fluorinated glyme.
20. The electrolyte of claim 17 , wherein the fluorinated glyme is 1,2-(1,1,2,2-tetrafluoroethoxy)-ethane (TFE).
21. The electrolyte of claim 20 , wherein the salt comprises lithium bis(fluorosulfonyl)imide.
22. The electrolyte of claim 1 , wherein the concentration of the salt is less than about 3M.
23. The electrolyte of claim 22 , wherein, in the solvent:diluent volumetric percentage ratio, the solvent is at least 50% and the diluent is no more than 50%.
24. The electrolyte of claim 22 , wherein, in the solvent:diluent volumetric percentage ratio, the solvent is at least 60% and the diluent is no more than 40%.
25. The electrolyte of claim 24 , wherein the salt comprises lithium bis(fluoro-sulfonyl)imide.
26. The electrolyte of claim 1 , wherein the salt comprises an alkali-metal salt.
27. The electrolyte of claim 26 , wherein the salt comprises a perfluorinated sulfonimide salt.
28. The electrolyte of claim 27 , wherein the perfluorinated sulfonimide salt comprises a lithium-based perfluorinated sulfonimide salt.
29. The electrolyte of claim 28 , wherein the lithium-based perfluorinated sulfonimide salt comprises lithium bis(fluorosulfonyl)imide.