Redox flow battery system with electrochemical recovery cell

Patent metadata

Field	Value
Publication number	US-11362359-B2
Application number	US-201916418120-A
Country	US
Kind code	B2
Filing date	May 21, 2019
Priority date	May 21, 2019
Publication date	Jun 14, 2022
Grant date	Jun 14, 2022

Abstract

A redox flow battery system includes a redox flow battery that has a redox flow cell, and a supply/storage system external of the redox flow cell. The supply/storage system includes first and second electrolytes for circulation through the redox flow cell. At least the first electrolyte is an aqueous liquid electrolyte that has electrochemically active species with multiple, reversible oxidation states. There is a gas vent passage connected with the redox flow battery to receive water byproduct that evolves from side reaction of the first electrolyte. A bypass passage is connected with the supply/storage system to receive the aqueous electrolyte. An electrochemical recovery cell includes a first half-cell connected to the gas vent passage to receive as a reactant the water byproduct and a second half-cell connected to the bypass passage to receive as a reactant the first electrolyte.

First claim

What is claimed is:

1. A redox flow battery system comprising:
a redox flow battery including
a redox flow cell, and
a supply/storage system external of the redox flow cell, the supply/storage system including first and second electrolytes for circulation through the redox flow cell, the first and second electrolytes being aqueous liquid electrolytes having electrochemically active species with multiple, reversible oxidation states;

a gas vent passage connected with the redox flow battery to receive water byproduct that evolves from side reaction of the first electrolyte;
a bypass passage connected with the supply/storage system to receive the second electrolyte; and
an electrochemical recovery cell including a first half-cell connected to the gas vent passage to receive as a reactant the water byproduct and a second half-cell connected to the bypass passage to receive as a reactant the second electrolyte, the first half-cell including a first electrode that has a metal catalyst including rhodium sulfide, Rh x S y and the second half-cell including a second electrode excluding any metal catalyst.

2. The redox flow battery system as recited in claim 1 , wherein the gas vent passage includes a pressure relief valve downstream of the supply/storage system and the electrochemical recovery cell such that flow of the water byproduct through the electrochemical recovery cell depends on pressure-release of the pressure relief valve.

3. The redox flow battery system as recited in claim 1 , wherein the supply/storage system includes at least one storage vessel, and the gas vent passage is connected with a headspace of the storage vessel.

4. The redox flow battery system as recited in claim 3 , further comprising an inert gas source connected with the headspace and maintaining a positive pressure in the headspace and the gas vent passage.

5. The redox flow battery system as recited in claim 3 , wherein downstream of the electrochemical recovery cell the bypass passage leads into the at least one storage vessel.

6. The redox flow battery system as recited in claim 1 , wherein the second electrode is carbon paper.

7. The redox flow battery system as recited in claim 1 , wherein the electrochemical recovery cell includes a separator between the first half-cell and the second half-cell, and the separator is an ion exchange membrane, has a thickness of 50 to 300 micrometers, and has a dimensionless selectivity of at least 1000.

8. The redox flow battery system as recited in claim 1 , further comprising an additional electrochemical recovery cell including an additional first half-cell and an additional second half-cell, an additional gas vent passage, and an additional bypass passage connected with the redox flow battery to receive water byproduct that evolves from side reaction of the second electrolyte, the additional first half-cell connected to the additional gas vent passage to receive as a reactant the water byproduct of the second electrolyte and the additional second half-cell connected to the additional bypass passage to receive as a reactant the first electrolyte.

9. The redox flow battery system as recited in claim 1 , further comprising a potentiostat controlling voltage of the electrochemical recovery cell.

10. A method for recovering water byproducts in a redox flow battery system, the method comprising: operating a redox flow battery that includes a redox flow cell and a supply/storage system external of the redox flow cell, the supply/storage system including first and second electrolytes that circulate through the redox flow cell during operation, at least the first electrolyte is an aqueous liquid electrolyte that has electrochemically active species with multiple, reversible oxidation states, wherein the aqueous electrolyte generating water byproduct from side reactions of the first electrolyte; capturing the water byproduct in a gas vent passage that is connected with the redox flow battery; and recovering the water byproduct by passing the water byproduct through a first half-cell of an electrochemical recovery cell and passing the aqueous electrolyte from a bypass passage that is connected with the supply/storage system through a second half-cell of the electrochemical recovery cell, the electrochemical recovery cell reacting the water byproduct to produce water that is incorporated in the aqueous electrolyte, wherein the first half-cell includes a first electrode that has a metal catalyst that includes rhodium sulfide, Rh x Sy and the second half-cell includes a second electrode that excludes any metal catalyst.

11. The method as recited in claim 10 , wherein the passing the water byproduct through the first half-cell depends on a pressure-release of a pressure relief valve downstream of the electrochemical recovery cell.

12. The method as recited in claim 10 , wherein the supply/storage system includes at least one storage vessel containing the first electrolyte, and the water byproduct is captured from a headspace of the storage vessel.

13. The method as recited in claim 12 , further comprising maintaining a positive pressure in the headspace and the gas vent passage using an inert gas source connected with the headspace.

14. The method as recited in claim 10 , wherein the second electrode is carbon paper.

15. The method as recited in claim 10 , wherein the electrochemical recovery cell includes a separator between the first half-cell and the second half-cell, and the separator is an ion exchange membrane, has a thickness of 50 to 300 micrometers, and has a dimensionless selectivity of at least 1000.

Assignees

• United Technologies Corp
• Raytheon Tech Corp

Inventors

• Perry Michael L
• Darling Robert Mason
• Saraidaridis James D

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M8/188 Primary

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

• H01M8/0662 Primary

  Treatment of gaseous reactants or gaseous residues, e.g. cleaning · CPC title