Aqueous redox flow batteries comprising metal ligand coordination compounds
This invention is directed to aqueous redox flow batteries comprising redox-active metal ligand coordination compounds. The compounds and configurations described herein enable flow batteries with performance and cost parameters that represent a significant improvement over that previous known in the art.
1. A composition comprising an ammonium or alkylammonium salt of a metal complex containing at least one substituted catecholate ligand.
2. The composition of claim 1 , wherein the at least one substituted catecholate ligand comprises a sulfonated catecholate ligand.
3. The composition of claim 1 , wherein the at least one substituted catecholate ligand comprises a hydroxycatecholate ligand.
4. The composition of claim 1 , wherein the metal complex contains two unsubstituted catecholate ligands and one substituted catecholate ligand.
5. The composition of claim 1 , wherein the metal complex contains one unsubstituted catecholate ligand and two substituted catecholate ligands.
6. The composition of claim 1 , wherein the metal complex comprises a metal selected from the group consisting of Al, Ca, Ce, Co, Cr, Fe, Mg, Mo, Sn, Ti, U, W, Zn and Zr.
7. The composition of claim 6 , wherein the metal complex comprises Ti.
8. An aqueous solution comprising the composition of claim 1 .
9. The aqueous solution of claim 8 , wherein the metal complex has a concentration of at least about 0.5 M in the aqueous solution.
10. The aqueous solution of claim 8 , wherein the at least one substituted catecholate ligand comprises a sulfonated catecholate ligand.
11. The aqueous solution of claim 8 , wherein the at least one substituted catecholate ligand comprises a hydroxycatecholate ligand.
12. The aqueous solution of claim 8 , wherein the metal complex contains two unsubstituted catecholate ligands and one substituted catecholate ligand.
13. The aqueous solution of claim 8 , wherein the metal complex contains one unsubstituted catecholate ligand and two substituted catecholate ligands.
14. The aqueous solution of claim 8 , wherein the metal complex comprises a metal selected from the group consisting of Al, Ca, Ce, Co, Cr, Fe, Mg, Mo, Sn, Ti, U, W, Zn and Zr.
15. The aqueous solution of claim 14 , wherein the metal complex comprises Ti.
16. The aqueous solution of claim 8 , wherein the aqueous solution has a pH ranging between about 9 to about 13.
17. The aqueous solution of claim 8 , wherein the aqueous solution has a pH ranging between about 8 to about 12.
18. A flow battery comprising:
a first half-cell containing a first aqueous electrolyte solution; and
a second half-cell containing a second aqueous electrolyte solution;
wherein at least one of the first aqueous electrolyte solution and the second aqueous electrolyte solution comprises an ammonium or alkylammonium salt of a metal complex containing at least one optionally substituted catecholate ligand.
19. The flow battery of claim 18 , wherein the metal complex contains at least one unsubstituted catecholate ligand and at least one substituted catecholate ligand.
20. The flow battery of claim 19 , wherein the at least one substituted catecholate ligand comprises a sulfonated catecholate ligand.
21. The flow battery of claim 19 , wherein the at least one substituted catecholate ligand comprises a hydroxycatecholate ligand.
22. The flow battery of claim 19 , wherein the metal complex contains two unsubstituted catecholate ligands and one substituted catecholate ligand.
23. The flow battery of claim 19 , wherein the metal complex contains one unsubstituted catecholate ligand and two substituted catecholate ligands.
24. The flow battery of claim 18 , wherein the metal complex contains three unsubstituted catecholate ligands.
25. The flow battery of claim 18 , wherein the metal complex comprises Ti.
26. The flow battery of claim 18 , wherein the metal complex has a concentration of at least about 0.5 Min the aqueous solution.