REDOX FLOW BATTERY SYSTEMS AND METHODS UTILIZING A BIPOLAR ELECTRODE STRUCTURE

1 . A redox flow battery system, comprising:

an anolyte;

a catholyte;

a first electrode structure comprising a base having a first surface and a second surface opposite the first surface, a first electrode disposed on the first surface of the base, a second electrode disposed on the second surface of the base, and conductive elements that extend through the base, wherein the base resists flow of anolyte and catholyte through the base and each of the conductive elements comprises a first end portion exposed at the first surface of the base and a second end portion exposed at the second surface of the base, wherein the first electrode comprises the first end portions of the conductive elements and the second electrode comprises the second end portions of the conductive elements;

a first half-cell in which the first electrode is in contact with the anolyte; and

a second half-cell in which the second electrode is in contact with the catholyte.

2 . The redox flow battery system of claim 1 , wherein the conductive elements comprise at least one of metal wires, carbon fibers, graphite fibers, or silicon carbide.

3 . The redox flow battery system of claim 1 , wherein the base comprises at least one of a plastic, resin, a carbon or graphite plate, or a metal or alloy plate.

4 . The redox flow battery system of claim 1 , wherein the base comprises polypropylene or polyethylene perfluoroalkoxy alkane, polyvinylidene fluoride, polytetrafluoroacetic acid, polyvinyl chloride, or chlorinated polyvinyl chloride.

5 . The redox flow battery system of claim 1 , wherein at least one of the first electrode or the second electrode comprises an additional conductive material.

6 . The redox flow battery system of claim 5 , wherein the additional conductive material comprises metal, carbon fiber, carbon felt, or silicon carbide.

7 . The redox flow battery system of claim 1 , wherein the anolyte comprises chromium ions in solution and the catholyte comprises iron ions in solution.

8 . The redox flow battery system of claim 7 , wherein the anolyte further comprises iron ions in solution and the anolyte comprises chromium ions in solution.

9 . The redox flow battery system of claim 1 , further comprising

a balance arrangement comprising

a balance electrolyte,

a second electrode structure comprising a base having a first surface and a second surface opposite the first surface, a third electrode disposed on the first surface of the base, a fourth electrode disposed on the second surface of the base, and conductive elements that extend through the base, wherein the base resists flow of anolyte and catholyte through the base and each of the conductive elements comprises a first end portion exposed at the first surface of the base and a second end portion exposed at the second surface of the base, wherein the third electrode comprises the first end portions of the conductive elements and the fourth electrode comprises the second end portions of the conductive elements,

a third half-cell comprising the third electrode in contact with the anolyte or the catholyte, and

a fourth half-cell comprising the fourth electrode in contact with the balance electrolyte.

10 . The redox flow battery system of claim 1 , wherein the balance electrolyte comprises vanadium ions in solution and the balance arrangement further comprises a reductant in the balance electrolyte or introducible to the balance electrolyte for reducing dioxovanadium ions.

11 . The redox flow battery system of claim 1 , wherein at least a portion of the chromium ions form a chromium complex with at least one of the following: NH 3 , NH 4 + , CO(NH 2 ) 2 , SCN − , or CS(NH 2 ) 2 .

12 . A method of making an electrode structure, the method comprising:

providing a base that is configured to resist flow of an electrolyte through the base; and

extending a plurality of conductive elements through the base so that each of the conductive elements comprises a first end portion exposed at a first surface of the base and a second end portion exposed at a second surface of the base, wherein the first electrode comprises the first end portions of the conductive elements and the second electrode comprises the second end portions of the conductive elements.

13 . The method of claim 12 wherein the extending comprises molding the base around portions of the conductive elements.

14 . The method of claim 12 , wherein the extending comprises pushing the conductive elements through the base.

15 . The method of claim 14 , further comprising heating the base to flow the base around the conductive elements.

16 . The method of claim 12 , further comprising disposing additional first conductive material over the first surface of the base, wherein the first electrode further comprises the additional first conductive material.

17 . The method of claim 16 , further comprising disposing additional second conductive material over the second surface of the base, wherein the second electrode further comprises the additional second conductive material.

18 . A method of operating the redox flow battery system of claim 1 , the method comprising:

charging the redox flow battery system by coupling a source to the first and second electrodes; and

discharging the redox flow battery system by coupling a load to the first and second electrodes.

19 . The method of claim 18 , wherein the anolyte comprises chromium ions in solution and the catholyte comprises iron ions in solution.

20 . The method of claim 19 , wherein the anolyte further comprises iron ions in solution and the anolyte comprises chromium ions in solution.