Redox flow battery with electrolyte balancing and compatibility enabling features

Patent metadata

Field	Value
Publication number	US-2020044267-A1
Application number	US-201816052727-A
Country	US
Kind code	A1
Filing date	Aug 2, 2018
Priority date	Aug 2, 2018
Publication date	Feb 6, 2020
Grant date	—

Abstract

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.

First claim

What is claimed is:

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 method for a redox flow battery, the method comprising:
using first and second cells of a redox flow battery to store input electrical energy upon charging and discharge the stored electrical energy upon discharging,
wherein each said cell has a separator layer arranged between first and second electrodes,
wherein the using includes
circulating a polysulfide electrolyte solution of pH 11.5 or greater through a first circulation loop in fluid connection with the first electrode of the first cell,
circulating an iron electrolyte solution of pH 3 or less through a second circulation loop in fluid connection with the second electrode of the second cell, and
circulating an intermediator electrolyte solution through a third circulation loop in fluid connection with the second electrode of the first cell and the first electrode of the second cell, and
sulfur from the polysulfide electrolyte solution in the first electrode of the first cell permeates through the ion-exchange layer of the first cell and precipitates as a solid sulfide product in the second electrode and iron from the iron electrolyte solution in the second electrode of the second cell permeates through the ion-exchange layer of the second cell and precipitates as solid iron product;
emptying the intermediator electrolyte solution from either the second electrode of the first cell or the first electrode of the second cell; and recovering either the solid sulfide product to the polysulfide electrolyte solution or the solid iron product to the iron electrolyte solution by, respectively,
circulating at least a portion of the polysulfide electrolyte solution from the first circulation loop through the second electrode to dissolve, and thereby remove, the solid sulfide product from the second electrode of the first cell, and then transferring the polysulfide electrolyte solution with the dissolved solid sulfide product back in to the first loop, or
circulating at least a portion of the iron electrolyte solution from the second circulation loop through the first electrode to dissolve, and thereby remove, the solid iron product from the first electrode of the second cell, and then transferring the iron electrolyte solution with the dissolved solid iron product back in to the second loop.

12 . The method as recited in claim 12 , including maintaining the intermediator electrolyte solution at a pH 12 or greater so that the iron precipitates upon permeation through the ion-exchange layer from the second electrode of the second cell into the first electrode of the second cell.

13 . The method as recited in claim 11 , including maintaining the intermediator electrolyte solution at a pH 12 or greater so that the sulfur precipitates upon permeation through the ion-exchange layer from the first electrode of the first cell into the second electrode of the first cell.

14 . A method for a redox flow battery, the method comprising:
using first and second cells of a redox flow battery to store input electrical energy upon charging and discharge the stored electrical energy upon discharging,
wherein each said cell has a separator layer arranged between first and second electrodes,
wherein the using includes
circulating a polysulfide electrolyte solution of pH 11.5 or greater through a first circulation loop in fluid connection with the first electrode of the first cell,
circulating an iron electrolyte solution of pH 3 or less through a second circulation loop in fluid connection with the second electrode of the second cell, and
circulating an intermediator electrolyte solution through a third circulation loop in fluid connection with the second electrode of the first cell and the first electrode of the second cell,
using a third cell to electrolyze either the polysulfide electrolyte solution to produce hydrogen gas or the iron electrolyte solution to produce oxygen gas; and maintaining the pH of polysulfide electrolyte solution to be pH 11.5 or greater or the pH of the iron electrolyte solution to be pH 3 or less by, respectively,
introducing the oxygen gas into the polysulfide electrolyte solution to adjust the pH of the polysulfide electrolyte solution, or
introducing the hydrogen gas into the iron electrolyte solution to adjust the pH of the iron electrolyte solution.

15 . The method as recited in claim 14 , wherein the introducing of the oxygen gas includes sparging the oxygen gas through the polysulfide electrolyte solution.

16 . The method as recited in claim 14 , wherein the introducing of the hydrogen gas includes sparging the hydrogen gas through the iron electrolyte solution.

17 . A method for a redox flow battery, the method comprising:
using a cell of a redox flow battery to store input electrical energy upon charging and discharge the stored electrical energy upon discharging,
wherein the cell has a separator layer arranged between first and second elect

Assignees

• United Technologies Corp

Inventors

• Perry Michael L

Classifications

• H01M8/188

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

• H01M8/08

  Fuel cells with aqueous electrolytes · CPC title

• H01M8/04186 Primary

  of liquid-charged or electrolyte-charged reactants · CPC title

• H01M2300/0014

  Alkaline electrolytes · CPC title

• H01M8/20

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