Redox flow battery with electrolyte balancing and compatibility enabling features
A redox flow battery includes first and second cells. Each cell has electrodes and a separator layer arranged between the electrodes. A first circulation loop is fluidly connected with the first electrode of the first cell. A polysulfide electrolyte solution has a pH 11.5 or greater and is contained in the first recirculation loop. A second circulation loop is fluidly connected with the second electrode of the second cell. An iron electrolyte solution has a pH 3 or less and is contained in the second circulation loop. A third circulation loop is fluidly connected with the second electrode of the first cell and the first electrode of the second cell. An intermediator electrolyte solution is contained in the third circulation loop. The cells are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.
1. A redox flow battery comprising:
first and second cells, each said cell having first and second electrodes and a separator layer arranged between the first and second electrodes;
a first circulation loop fluidly connected with the first electrode of the first cell;
a polysulfide electrolyte solution having a pH 11.5 or greater contained in the first recirculation loop;
a second circulation loop fluidly connected with the second electrode of the second cell;
an iron electrolyte solution having a pH 3 or less contained in the second circulation loop;
a third circulation loop fluidly connected with the second electrode of the first cell and the first electrode of the second cell; and
an intermediator electrolyte solution contained in the third circulation loop,
wherein the polysulfide electrolyte solution and the intermediator electrolyte solution in the first cell, and the iron electrolyte solution and the intermediator electrolyte solution in the second cell, are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.
2. The redox flow battery as recited in claim 1 , wherein the intermediator electrolyte solution has a pH 12 or greater.
3. The redox flow battery as recited in claim 2 , wherein the first cell has standard electrode potential of greater than −0.3V SHE.
4. The redox flow battery as recited in claim 1 , wherein the intermediator electrolyte solution includes at least one of quinoxaline, anthraquinone, or benzoquinone.
5. The redox flow battery as recited in claim 4 , wherein the intermediator electrolyte solution includes 1,2-benzoquinone-3,5-disulfonic acid.
6. The redox flow battery as recited in claim 4 , wherein the intermediator electrolyte solution includes at least one of 2,6-DBEAQ, 1,2-DBEAQ, or 1,8-DBEAQ.
7. The redox flow battery as recited in claim 1 , wherein the first circulation loop includes a bypass line and a third cell in the bypass line, the third cell operable to electrolyze the polysulfide electrolyte solution to produce hydrogen gas.
8. The redox flow battery as recited in claim 7 , wherein the third cell is connected by a hydrogen bleed line to the second circulation loop.
9. The redox flow battery as recited in claim 1 , wherein the second circulation loop includes a bypass line and a third cell in the bypass line, the third cell operable to electrolyze the iron electrolyte solution to produce oxygen gas.
10. The redox flow battery as recited in claim 9 , wherein the third cell is connected by an oxygen bleed line to the first circulation loop.
11. A redox flow battery comprising:
a cell having first and second electrodes and an ion-exchange layer arranged between the first and second electrodes;
a first circulation loop fluidly connected with the first electrode;
a polysulfide electrolyte solution having a pH 11.5 or greater contained in the first recirculation loop;
a second circulation loop fluidly connected with the second electrode;
an iron or manganate electrolyte solution contained in the second circulation loop;
a bi-directional filter;
a first auxiliary loop fluidly connecting the first circulation loop with the second electrode through the bi-directional filter; and
a second auxiliary loop fluidly connecting the second circulation loop with the first electrode through the bi-directional filter.