Redox flow battery with electrolyte balancing and compatibility enabling features

Patent metadata

Field	Value
Publication number	US-11637298-B2
Application number	US-202117361385-A
Country	US
Kind code	B2
Filing date	Jun 29, 2021
Priority date	Aug 2, 2018
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

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 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.

2. The method as recited in claim 1 , 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.

3. The method as recited in claim 1 , 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.

4. 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.

5. The method as recited in claim 4 , wherein the introducing of the oxygen gas includes sparging the oxygen gas through the polysulfide electrolyte solution.

6. The method as recited in claim 4 , wherein the introducing of the hydrogen gas includes sparging the hydrogen gas through the iron electrolyte solution.

7. 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 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 cell,
circulating an manganate electrolyte solution through a second circulation loop in fluid connection with the second electrode of the cell, and
sulfur from the polysulfide electrolyte solution in the first electrode permeates through the ion-exchange layer and precipitates as a solid sulfide product in the second electrode and manganese from the manganate electrolyte solution in the permeates through the ion-exchange layer of the second cell and precipitates as solid iron product in the first electrode;

recovering either the solid sulfide product to the polysulfide electrolyte solution or the solid manganese product to the manganate 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, 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 manganate electrolyte solution from the second circulation loop through the first electrode to dissolve, and thereby remove, the solid manganese product from the first electrode, and then transferring the manganese electrolyte solution with the dissolved solid iron product back in to the second loop.

8. The method as recited in claim 7 , further comprising passing the polysulfide electrolyte solution with the dissolved solid sulfide product in a first direction through a bi-directional filter and passing the manganate electrolyte solution with the dissolved solid manganese product in a second, opposite direction through the bi-directional filter.

Assignees

• Raytheon Tech Corp

Inventors

• Perry Michael L

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M8/184 Primary

  Regeneration by electrochemical means · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M8/2455

  with liquid, solid or electrolyte-charged reactants · CPC title

• H01M8/20

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