Mitigation of crossover within flow batteries

Patent metadata

Field	Value
Publication number	US-2017271704-A1
Application number	US-201615076538-A
Country	US
Kind code	A1
Filing date	Mar 21, 2016
Priority date	Mar 21, 2016
Publication date	Sep 21, 2017
Grant date	—

Abstract

Crossover of active materials in an electrochemical cell can detrimentally impact operating performance, particularly for flow batteries. Flow batteries with tolerance toward crossover of active materials can incorporate a first half-cell containing a first electrolyte solution that includes a coordination complex as a first active material, and a second half-cell containing a second electrolyte solution that includes an unbound form of an organic compound as a second active material. The coordination complex contains a redox-active metal center and an organic compound bound to the redox-active metal center. The unbound form of the organic compound in the second electrolyte solution is the same as the bound organic compound in the first electrolyte solution, or an oxidized or reduced variant thereof. Catechol and substituted catechols can be particularly desirable organic compounds for inclusion in the coordination complex and the second electrolyte solution.

First claim

What is claimed is the following:

1 . A flow battery comprising:
a first half-cell containing a first electrolyte solution, the first electrolyte solution comprising a coordination complex as a first active material;
wherein the coordination complex comprises a redox-active metal center and an organic compound bound to the redox-active metal center; and
a second half-cell containing a second electrolyte solution, the second electrolyte solution comprising an unbound form of the organic compound, or a corresponding oxidized or reduced variant thereof, as a second active material.

2 . The flow battery of claim 1 , wherein the redox-active metal center is a transition metal.

3 . The flow battery of claim 1 , wherein the organic compound lacks redox activity when bound to the redox-active metal center.

4 . The flow battery of claim 1 , wherein the organic compound comprises catechol, a substituted catechol, or any combination thereof.

5 . The flow battery of claim 4 , wherein the organic compound comprises at least a monosulfonated catechol.

6 . The flow battery of claim 1 , wherein the coordination complex comprises both Na + and K + counterions.

7 . The flow battery of claim 1 , wherein the first half-cell is a negative half-cell and the second half-cell is a positive half-cell.

8 . The flow battery of claim 1 , wherein the second electrolyte solution has a pH at which the coordination complex degrades or disassociates to form the unbound form of the organic compound, or the corresponding oxidized or reduced variant thereof.

9 . A flow battery comprising:
a first half-cell containing a first electrolyte solution, the first electrolyte solution comprising a coordination complex as a first active material and the first half-cell being a negative half-cell;
wherein the coordination complex comprises a redox-active metal center and an organic compound comprising catechol, a substituted catechol, or any combination thereof bound to the redox-active metal center; and
a second half-cell containing a second electrolyte solution, the second electrolyte solution comprising an unbound form of the organic compound, or a corresponding quinone variant thereof, as a second active material and the second half-cell being a positive half-cell.

10 . The flow battery of claim 9 , wherein the redox-active metal center is titanium.

11 . The flow battery of claim 9 , wherein the redox-active metal center is a transition metal.

12 . The flow battery of claim 11 , wherein the coordination complex has a formula of
D g M(L 1 )(L 2 )(L 3 ); wherein M is the transition metal; D is NH 4 + , Li + , Na + , K + , or any combination thereof; g ranges between 2 and 6; and L 1 , L 2 and L 3 are ligands, at least one of L 1 , L 2 and L 3 being catechol or the substituted catechol.

13 . The flow battery of claim 12 , wherein each of L 1 , L 2 and L 3 is catechol or the substituted catechol.

14 . The flow battery of claim 12 , wherein at least one of L 1 , L 2 and L 3 is a monosulfonated catechol.

15 . The flow battery of claim 12 , wherein the transition metal is titanium.

16 . The flow battery of claim 9 , wherein the organic compound comprises at least a monosulfonated catechol.

17 . The flow battery of claim 9 , wherein the coordination complex comprises both Na + and K + counterions.

18 . The flow battery of claim 9 , wherein the second electrolyte solution has a pH at which the coordination complex degrades or disassociates to form the unbound form of the organic compound, or the corresponding quinone variant thereof.

19 . The flow battery of claim 9 , wherein the first electrolyte solution has an alkaline pH and the second electrolyte solution has an acidic pH.

20 . A method comprising:
providing a first electrolyte solution comprising a coordination complex as a first active material;
wherein the coordination complex comprises a redox-active metal center and an organic compound comprising catechol, a substituted catechol, or any combination thereof bound to the redox-active metal center;
providing a second electrolyte solution comprising an unbound form of the organic compound, or a corresponding quinone variant thereof, as a second active material; disposing the first electrolyte solution and the second electrolyte solution on opposing sides of a separator in a flow battery; and operating the flow battery by reducing the redox-active metal center of the coordination complex in the first electrolyte solution and oxidizing the catechol or substituted catechol in the second electrolyte solution to the corresponding quinone variant, or oxidizing the redox-active metal center of the coordination complex in the first electrolyte solution and reducing the corresponding quinone variant in the second electrolyte solution to catechol or the substituted catechol.

21 . The method of claim 20 , wherein at least a portion of the coordination complex crosses the separator and enters the second electrolyte solution, the method further comprising:
degrading or disassociating the coordination complex to form additional catechol or substituted catechol, or the corresponding quinone variant thereof, in the second electrolyte solution.

22 . The method of claim 21 , wherein the second electrolyte solution has a pH at which the coordination complex degrades or disassociates to form the unbound form of the organic compound.

23 . The method of claim 21 , wherein the first electrolyte solution is present in a negative half-cell of the flow battery and the second electrolyte solution is present in a positive half-cell of the flow battery.

24 . The method of claim 20 , wherein the redox-active metal center is titanium.

Assignees

• Lockheed Martin Advanced Energy Storage Llc

Inventors

• Morris-Cohen Adam

Classifications

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/0289

  Means for holding the electrolyte (solid polymer electrolytes H01M8/1018) · CPC title

• H01M8/0202

  Collectors; Separators, e.g. bipolar separators; Interconnectors · CPC title

• H01M8/20

  Indirect fuel cells, e.g. fuel cells with redox couple being irreversible (H01M8/18 takes precedence) · CPC title

• Y02E60/50

  Fuel cells · CPC title