Electrolyte compositions for aqueous electrolyte lithium sulfur batteries
Provided are lithium sulfur battery cells that use water as an electrolyte solvent. In various embodiments the water solvent enhances one or more of the following cell attributes: energy density, power density and cycle life. Significant cost reduction can also be realized by using an aqueous electrolyte in combination with a sulfur cathode. For instance, in applications where cost per Watt-Hour (Wh) is paramount, such as grid storage and traction applications, the use of an aqueous electrolyte in combination with inexpensive sulfur as the cathode active material can be a key enabler for the utility and automotive industries, providing a cost effective and compact solution for load leveling, electric vehicles and renewable energy storage.
1. An aqueous lithium sulfur electrochemical cell comprising:
an anode structure comprising an electroactive material;
a cathode comprising a solid electron transfer medium;
an aqueous electrolyte comprising at least 10 vol % of a non-aqueous solvent and greater than 10 vol % of water in direct contact with the electron transfer medium; and
active sulfur species in direct contact with the aqueous electrolyte;
wherein the anode electroactive material is isolated from direct contact with the aqueous electrolyte.
2. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the amount of water in the aqueous electrolyte is greater than 20 vol %.
3. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the amount of water in the aqueous electrolyte is greater than 30%.
4. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the amount of water in the aqueous electrolyte is greater than 40%.
5. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein water is the main solvent.
6. The aqueous lithium sulfur electrochemical cell of claim 5 , wherein the amount of non-aqueous solvent in the aqueous electrolyte is between 10 and 20 vol %.
7. The aqueous lithium sulfur electrochemical cell of claim 5 wherein the amount of non-aqueous solvent in the aqueous electrolyte is between 20 and 30 vol %.
8. The aqueous lithium sulfur electrochemical cell of claim 5 , wherein the amount on non-aqueous solvent in the aqueous electrolyte is between 30 and 40 vol %.
9. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the amount of non-aqueous solvent in the aqueous electrolyte is up to 80 vol %.
10. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the active sulfur concentration in the aqueous electrolyte is greater than 8 molar sulfur.
11. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the active sulfur concentration in the aqueous electrolyte is greater than 10 molar sulfur.
12. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the active sulfur concentration in the aqueous electrolyte is greater than 11 molar sulfur.
13. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the active sulfur concentration in the aqueous electrolyte is greater than 12 molar sulfur.
14. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the active lithium sulfur stoichiometric ratio in the electrolyte is Li 2 S x (x>5).
15. The aqueous lithium sulfur electrochemical cell of claim 14 , wherein active sulfur concentration in the aqueous electrolyte is between 10 and 17 molar.
16. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the non-aqueous solvent is a protic organic liquid solvent.
17. The aqueous lithium sulfur electrochemical cell of claim 16 , wherein the solvent is an amine.
18. The aqueous lithium sulfur electrochemical cell of claim 17 , wherein the solvent is a diamine.
19. The aqueous lithium sulfur electrochemical cell of claim 16 , wherein the solvent is an alcohol.
20. The aqueous lithium sulfur electrochemical cell of claim 19 , wherein the alcohol is selected from the group consisting of methanol, glycols and polyglycols.
21. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the non-aqueous solvent is aprotic.
22. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the non-aqueous solvent has a donor number between 15 to 40.
23. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the active sulfur concentration of the aqueous electrolyte prior to initially operating the cell is selected from the group consisting of a value that is greater than 5 molar sulfur, greater than 6 molar sulfur, greater than 7 molar sulfur, greater than 8 molar sulfur, greater than 9 molar sulfur, greater than 10 molar sulfur, greater than 11 molar sulfur, and greater than 12 molar sulfur.
24. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the lithium electroactive material is lithium metal.
25. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the lithium electroactive material comprises a lithium intercalation material.
26. The aqueous lithium sulfur electrochemical cell of claim 25 , wherein the lithium intercalation material is carbon.
27. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the lithium electroactive material comprises lithium alloy material.
28. The aqueous lithium sulfur electrochemical cell of claim 27 , wherein the lithium alloy material comprises silicon.
29. The aqueous lithium sulfur electrochemical cell of claim 1 , wherein the cell is a secondary lithium battery cell.