AQUEOUS REDOX FLOW BATTERIES COMPRISING MATCHED IONOMER MEMBRANES

• US 20140051002A1
• Filed: 07/24/2013
• Published: 02/20/2014
• Est. Priority Date: 07/27/2012
• Status: Active Grant

• Current Assignee: Lockheed Martin Energy LLC (Martin Marietta Corporation)
• Original Assignee: Sun Catalytix Corporation (Martin Marietta Corporation)
• Inventors: ESSWEIN, ARTHUR J., GOELTZ, JOHN, REECE, STEVEN Y., KING, EVAN R., AMADEO, DESIREE, TYAGI, NITIN, JARVI, THOMAS D.
• Granted Patent: US 9,692,077 B2
• Time in Patent Office: Days
• US Class Current: 429/451
• CPC Class Codes: H01M 8/1032 having sulfur, e.g. sulfonated-polyethersulfones [S-PES]
• CPC Class Codes: H01M 8/1039 halogenated, e.g. sulfonated polyvinylidene fluorides
• CPC Class Codes: H01M 8/1067 characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
• 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 60/50 Fuel cells

Abstract

This invention is directed to aqueous redox flow batteries comprising ionically charged redox active materials and ionomer membranes, wherein the charge of the redox active materials is of the same sign as that of the ionomer, so as to confer specific improvements.

Claims

1. A flow battery comprising:

a first aqueous electrolyte comprising a first redox active material;

a second aqueous electrolyte comprising a second redox active material;

a first electrode in contact with said first aqueous electrolyte;

a second electrode in contact with said second aqueous electrolyte; and

a separator comprising an ionomer membrane disposed between said first and second aqueous electrolytes;

wherein the sign of the net ionic charge of the first, second, or both redox active materials matches that of the ionomer membrane; and

wherein the flow battery operates or is capable of operating;

(a) where the first or second redox active materials comprise 3% or less of the molar flux of ions passing through the ionomer membrane;

or

(b) with a round trip current efficiency that is at least about 95%;

or

(c) at a current density of at least 100 mA/cm² with a round trip voltage efficiency of at least about 90%;

or

(d) with the electrolytes having an energy density of at least about 30 Wh/L;

or

(e) with a combination of any two or more of (a), (b), (c), and (d).

2. The flow battery of claim 1, wherein the sign of the net ionic charge of the first, second, or both redox active materials is the same in both oxidized and reduced forms of the redox active materials and matches that of the ionomer membrane.

3. The flow battery of claim 1, wherein the ionomer membrane has a thickness of less than 100 μ

m.

4. The flow battery of claim 1, where the first redox active material, the second redox active material or both first and second redox active materials comprises a metal ligand coordination compound.

5. The flow battery of claim 1, wherein the first and second redox active materials comprise first and second metal ligand coordination compounds, respectively, the first metal ligand coordination compound being different than the second metal ligand coordination compound.

6. The flow battery of claim 1, wherein the ion selective membrane comprises a fluoropolymer.

7. The flow battery of claim 1, the ion selective membrane comprising an ionomer having covalently attached or embedded sulfonate, carboxylate, quaternary ammonium, sulfonium, phosphazenium, and guanidinium residues or salts thereof.

8. The flow battery of claim 1, wherein at least one of the first and second redox materials exhibits substantially reversible electrochemical kinetics.

9. The flow battery of claim 1, wherein at least one of the electrodes presents a surface of an allotrope of carbon to the respective electrolyte.

10. The flow battery of claim 1, wherein both of the electrodes presents a surface of an allotrope of carbon to the respective electrolyte.

11. The flow battery of claim 1, wherein the pH of each of the first or second aqueous electrolytes or the pH of both the first and second aqueous electrolytes each exhibits a pH in a range of about 7 to about 13, about 8 to about 13, about 9 to about 13, about 10 to about 13, about 10 to about 12, or about 11.

12. The flow battery of claim 1, wherein both the first and second ionically charged redox active materials and their respective oxidized or reduced forms are negatively charged and wherein the ion selective membrane has a stationary phase that also has a net negative charge, so as to be selectively permeable to cations to the substantial exclusion of the negatively charged redox active materials.

13. The flow battery of claim 12, wherein the first and second redox active materials and their respective oxidized or reduced forms independently exhibit charges in a range of −

2 to −

5.

14. The flow battery of claim 1, where both the first and second ionically charged redox active materials and their respective oxidized or reduced forms are positively charged and wherein the ion selective membrane has a stationary phase that also has a net positive charge, so as to be selectively permeable to anions to the substantial exclusion of the positively charged redox active materials.

15. The flow battery of claim 14, wherein the first and second redox active materials and their respective oxidized or reduced forms independently exhibit charges in a range of +2 to +5 over the respective potential ranges.

16. The flow battery of claim 1, which when operating exhibits a round trip current efficiency of at least 98% over a state-of-charge in a range of from about 35 to about 65%.

17. The flow battery of claim 1, further comprising an external electrical circuit in electrical communication with the first and second electrodes, said circuit capable of charging or discharging the flow battery.

18. The flow battery of claim 1, the electrochemical cell capable of providing an energy density of at 10 Wh/L, at least 20 Wh/L, or at least 30 Wh/L.

19. A method of operating a flow battery of claim 1, said method comprising charging said battery by the input of electrical energy or discharging said battery by the removal of electrical energy.

20. A method of operating a flow battery of claim 1, said method comprising applying a potential difference across the first and second electrodes, with an associated flow of electrons, so as to:

(a) reduce the first redox active material while oxidizing the second redox active material;

or

(b) oxidize the first redox active material while reducing the second redox active material.

21. A system comprising:

a flow battery of claim 1 and the system further comprising;

(a) a first chamber containing the first aqueous electrolyte and a second chamber containing the second aqueous electrolyte;

(b) at least one electrolyte circulation loop in fluidic communication with each electrolyte chamber, said at least one electrolyte circulation loop comprising a storage tank and piping for containing and transporting the electrolytes;

(c) control hardware and software; and

(d) an optional power conditioning unit.

22. The system of claim 21, the system being adapted for connection to an electrical grid configured so as to provide renewables integration, peak load shifting, grid firming, baseload power generation/consumption, energy arbitrage, transmission and distribution asset deferral, weak grid support, frequency regulation, or a combination thereof.

23. The system of claim 21, the system being configured to provide stable power for remote camps, forward operating bases, off-grid telecommunications, or remote sensors.