Iron-Sulfide Redox Flow Batteries

• US 20120244406A1
• Filed: 03/25/2011
• Published: 09/27/2012
• Est. Priority Date: 03/25/2011
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Xia, Guanguang, Yang, Zhenguo, Li, Liyu, Kim, Soowhan, Liu, Jun, Graff, Gordon L.
• Granted Patent: US 8,609,270 B2
• Time in Patent Office: Days
• US Class Current: 429/107
• CPC Class Codes: H01M 4/9083 on carbon or graphite
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: H01M 4/96 Carbon-based electrodes
• CPC Class Codes: H01M 8/18 Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
• CPC Class Codes: H01M 8/188 by recharging of redox couples containing fluids; Redox flow type batteries
• CPC Class Codes: H01M 8/20 Indirect fuel cells, e.g. fuel cells with redox couple being irreversible H01M8/18 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

Iron-sulfide redox flow battery (RFB) systems can be advantageous for energy storage, particularly when the electrolytes have pH values greater than 6. Such systems can exhibit excellent energy conversion efficiency and stability and can utilize low-cost materials that are relatively safer and more environmentally friendly. One example of an iron-sulfide RFB is characterized by a positive electrolyte that comprises Fe(III) and/or Fe(II) in a positive electrolyte supporting solution, a negative electrolyte that comprises S²⁻ and/or S in a negative electrolyte supporting solution, and a membrane, or a separator, that separates the positive electrolyte and electrode from the negative electrolyte and electrode.

Claims

1. A redox flow battery system characterized by a positive electrolyte comprising Fe(III) and Fe(II) in a positive electrolyte supporting solution, a negative electrolyte comprising S²⁻

and S in an negative electrolyte supporting solution, and a membrane or a separator separating the positive electrolyte solution and electrode from the negative electrolyte solution and electrode.

2. The system of claim 1, wherein concentrations of the Fe(II) and Fe(III) are greater than 0.2 M.

3. The system of claim 1, wherein concentrations of the S²⁻

and S are greater than 0.1 M.

4. The system of claim 1, having a cell temperature between −

10°

C. and 60°

C. during operation.

5. The system of claim 1, wherein the positive electrolyte and negative electrolyte supporting solutions have pH values greater than or equal to 6.

6. The system of claim 5, wherein the positive electrolyte and negative electrolyte supporting solutions comprise alkali metal hydroxide, ammonium hydroxide, or both.

7. The system of claim 1, wherein the negative electrolyte comprises a polysulfide compound.

8. The system of claim 1, wherein the positive electrolyte comprises potassium ferricyanide, potassium ferrocyanide, or both.

9. The system of claim 1, having a state-of-charge condition greater than 0% and less than 100% during operation.

10. The system of claim 1, wherein the electrodes comprise carbon.

11. The system of claim 10, wherein the carbon electrodes comprise graphite felt.

12. The system of claim 10, wherein the carbon electrodes further comprise a Ni coating or a Co coating.

13. The system of claim 1, wherein the electrodes comprise noble metals.

14. The system of claim 11, wherein the noble metal electrodes comprise a metal selected from the group consisting of Ni, Co, Au, Pt, and stainless steels.

15. The system of claim 1, wherein the membrane or the separator comprises a sulfonated tetrafluoroethylene based fluoropolymer-copolymer.

16. The system of claim 1, wherein the membrane or the separator comprises a hydrocarbon.

17. A redox flow battery system characterized by:

a positive electrolyte comprising K₄F(CN)₆, K₃F(CN)₆, or both and NaOH;

a negative electrolyte comprising S²⁻

and S and NaOH; and

a membrane or a separator separating the positive electrolyte and negative electrolyte, wherein at least a portion of the S is arranged as sodium polysulfide.