Aqueous redox flow batteries featuring improved cell design characteristics
Provided are compositions having the formula M n Ti(L1)(L2)(L3) wherein L1 is a catecholate, and L2 and L3 are each independently selected from catecholates, ascorbate, citrate, glycolates, a polyol, gluconate, glycinate, hydroxyalkanoates, acetate, formate, benzoates, malate, maleate, phthalates, sarcosinate, salicylate, oxalate, a urea, polyamine, aminophenolates, acetylacetone or lactate; each M is independently Na, Li, or K; n is 0 or an integer from 1-6. Also provided are energy storage systems.
1. A composition comprising:
a titanium complex containing at least one unsubstituted catecholate ligand and at least one substituted catecholate, wherein at least one of the substituted catecholate ligands is a sulfonated catecholate ligand; and
sodium and potassium counterions.
2. The composition of claim 1 , wherein the titanium complex contains a hydroxycatecholate ligand.
3. The composition of claim 1 , wherein the titanium complex contains two unsubstituted catecholate ligands and the one sulfonated catecholate ligand.
4. The composition of claim 1 , wherein the titanium complex contains one unsubstituted catecholate ligand, one sulfonated catecholate ligand, and at least one ligand selected from the group consisting of, ascorbate, citrate, glycolate, a polyol, gluconate, glycinate, a hydroxyalkanoate, acetate, formate, benzoate, malate, maleate, phthalate, sarcosinate, salicylate, oxalate, a urea, a polyamine, an aminophenolate, acetylacetonate, and lactate.
5. The composition of claim 1 , wherein the sodium and potassium counterions are present in substantially equal molar amounts.
6. An aqueous solution comprising the composition of claim 1 .
7. The aqueous solution of claim 6 , wherein the titanium complex has a concentration of at least about 0.5 M in the aqueous solution.
8. The aqueous solution of claim 6 , wherein the titanium complex contains a hydroxycatecholate ligand.
9. The aqueous solution of claim 6 , wherein the titanium complex contains two unsubstituted catecholate ligands and one sulfonated catecholate ligand.
10. The aqueous solution of claim 6 , wherein the titanium complex contains one unsubstituted catecholate ligand, one sulfonated catecholate ligand, and at least-one ligand selected from the group consisting of ascorbate, citrate, glycolate, a polyol, gluconate, glycinate, a hydroxyalkanoate, acetate, formate, benzoate, malate, maleate, phthalate, sarcosinate, salicylate, oxalate, a urea, a polyamine, an aminophenolate, acetylacetonate, and lactate.
11. The aqueous solution of claim 6 , wherein substantially equal molar quantities of the sodium and potassium counterions are present.
12. A flow battery comprising:
a first half-cell containing a first electrolyte solution; and
a second half-cell containing a second electrolyte solution;
wherein at least one of the first electrolyte solution and the second electrolyte solution comprises the aqueous solution of claim 6 .