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 essentially of:
at least one salt;
a solvent that consists of one or more glymes each 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 at least one salt is soluble in the solvent; and
a diluent that consists of one or more components each selected from the group consisting of a fluorinated glyme and a fluorinated ether;
wherein:
the at least one 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 9:1; and
the electrolyte has a volumetric solvent:diluent percentage ratio of about 50:50 to about 90:10.
2. An electrochemical cell, comprising:
an anode designed and configured to plate with a metal during charging of the electrochemical cell;
a cathode;
a porous separator located between and electrically separating the anode and the cathode; and
an electrolyte permeating the porous separator and in operative communication with each of the anode and cathode, the electrolyte comprising:
at least one salt;
a solvent that consists of one or more glymes each 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 at least one salt is soluble in the solvent; and
a diluent that consists of one or more components each selected from the group consisting of a fluorinated glyme and a fluorinated ether;
wherein:
the at least one 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 9:1;
the electrolyte has a volumetric solvent:diluent percentage ratio of about 50:50 to about 90:10; and
the electrolyte consists essentially of the at least one salt, the solvent, and the diluent.
3. The electrochemical cell of claim 2 , wherein the anode is a lithium-metal anode.
4. The electrochemical cell of claim 2 , wherein the electrolyte does not include any nonfluorinated cyclic carbonate solvent.
5. The electrochemical cell of claim 2 , wherein the salt comprises a lithium-based salt.
6. The electrochemical cell of claim 2 , wherein the concentration of the salt is in a range of about 1M to less than 5M.
7. The electrochemical cell of claim 2 , having a solvent:salt molar ratio is about 2:1.
8. The electrochemical cell of claim 2 , wherein R 1 =R 2 .
9. The electrochemical cell of claim 2 , wherein the hydrocarbon sidechain has 2 to 6 carbon atoms.
10. The electrochemical cell of claim 2 , 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 electrochemical cell of claim 2 , wherein each of the at least one salt is a lithium salt.
12. The electrochemical cell of claim 11 , wherein the anode is a lithium-metal anode.
13. The electrochemical cell of claim 2 , wherein the salt comprises a perfluorinated sulfonimide salt.
14. The electrochemical cell of claim 13 , wherein the perfluorinated sulfonimide salt comprises a lithium-based perfluorinated sulfonimide salt.
15. The electrochemical cell of claim 14 , wherein the lithium-based perfluorinated sulfonimide salt comprises lithium bis(fluorosulfonyl)imide.
16. The electrochemical cell of claim 2 , wherein n=1 and each of R 1 and R 2 is an ethyl group, as in 1,2-diethoxyethane (DEE).
17. The electrochemical cell of claim 16 , wherein the diluent comprises a fluorinated ether.
18. The electrochemical cell of claim 16 , wherein the diluent comprises a fluorinated glyme.
19. The electrochemical cell of claim 16 , wherein the fluorinated glyme is 1,2-(1,1,2,2-tetrafluoroethoxy)-ethane (TFE).
20. The electrochemical cell of claim 19 , wherein the salt comprises lithium bis(fluorosulfonyl)imide.