GAS VENT FOR ELECTROCHEMICAL CELL

• US 20130095393A1
• Filed: 08/03/2012
• Published: 04/18/2013
• Est. Priority Date: 08/05/2011
• Status: Active Grant

• Current Assignee: Form Energy, Inc.
• Original Assignee: Fluidic, Inc.
• Inventors: TRIMBLE, Todd, GOODFELLOW, Andrew, FRIESEN, Cody A, MIHALKA, Michael, FRIESEN, Grant, KRISHNAN, Ramkumar
• Granted Patent: US 9,214,708 B2
• Time in Patent Office: Days
• US Class Current: 429/404
• CPC Class Codes: H01M 12/06 with one metallic and one gaseous electrode
• CPC Class Codes: H01M 12/08 composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
• CPC Class Codes: H01M 4/86 Inert electrodes with catalytic activity, e.g. for fuel cells
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 50/30 Arrangements for facilitating escape of gases
• CPC Class Codes: H01M 50/342 Non-re-sealable arrangements
• CPC Class Codes: H01M 50/375 Vent means sensitive to or responsive to temperature
• CPC Class Codes: H01M 50/394 Gas-pervious parts or elements
• CPC Class Codes: H01M 8/225 Fuel cells in which the fuel is based on materials comprising particulate active material in the form of a suspension, a dispersion, a fluidised bed or a paste
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An electrochemical cell system is configured to utilize an ionically conductive medium flowing through a plurality of electrochemical cells. One or more gas vents are provided along a flow path for the ionically conductive medium, so as to permit gasses that evolve in the ionically conductive medium during charging or discharging to vent outside the cell system, while constraining the ionically conductive medium within the flow path of the electrochemical cell system.

Claims

1. An electrochemical cell system comprising:

one or more electrochemical cells, each comprising;

(i) a fuel electrode comprising a metal fuel; and

(ii) an oxidant electrode spaced from the fuel electrode;

a liquid ionically conductive medium for conducting ions between the fuel and oxidant electrodes to support electrochemical reactions at the fuel and oxidant electrodes;

a housing configured to contain the ionically conductive medium in the one or more electrochemical cells; and

a gas permeable and liquid impermeable membrane positioned along a portion of the housing and configured to close the portion of the housing to contain the ionically conductive medium therein but permit gas in the housing to permeate therethrough for venting of the gas from the one or more electrochemical cells;

wherein the fuel electrode and the oxidant electrode are configured to, during discharge, oxidize the metal fuel at the fuel electrode and reduce an oxidant at the oxidant electrode to generate a discharge potential difference therebetween for application to a load.

2. The electrochemical cell system of claim 1, wherein the gas permeable and liquid impermeable membrane comprises a fluoropolymer material

3. The electrochemical cell system of claim 2, wherein the fluoropolymer material comprises polytetrafluoroethylene.

4. The electrochemical cell system of claim 1, wherein the liquid ionically conductive medium is configured to flow in a flow path through and among the one or more electrochemical cells.

5. The electrochemical cell system of claim 4, wherein the gas permeable and liquid impermeable membrane is positioned downstream along the flow path from the fuel electrode and the oxidant electrode, and configured to vent by permeation gases generated during electrochemical reactions at the fuel and oxidant electrodes.

6. The electrochemical cell system of claim 4, wherein the gas permeable and liquid impermeable membrane is configured to contact the ionically conductive medium while it flows through the flow path.

7. The electrochemical cell system of claim 5, wherein the housing comprises a cell module configured to receive the fuel electrode, and at least one sidewall configured to receive the oxidant electrode and the gas permeable and liquid impermeable membrane, wherein the at least one sidewall is assembled onto the cell module to constrain the ionically conductive medium to the flow path.

8. The electrochemical cell system of claim 1, wherein a portion of the gas permeable and liquid impermeable membrane comprises the oxidant electrode.

9. The electrochemical cell system of claim 1, wherein each electrochemical cell further comprises a charging electrode selected from the group consisting of (a) the oxidant electrode, (b) a separate charging electrode spaced from the fuel and oxidant electrodes, and (c) a portion of the fuel electrode.

10. The electrochemical cell system of claim 9, wherein the fuel electrode and the charging electrode are configured to, during re-charge, reduce a reducible species of the metal fuel to electrodeposit the metal fuel on the fuel electrode and oxidize an oxidizable species of the oxidant by application of a re-charge potential difference therebetween from a power source.

11. The electrochemical cell system of claim 10, wherein the fuel electrode comprises a series of permeable electrode bodies arranged in spaced apart relation;

wherein the spaced apart relation of the permeable electrode bodies enables the re-charge potential difference to be applied between the charging electrode and at least one of the permeable electrode bodies, with the charging electrode functioning as the anode and the at least one permeable electrode body functioning as the cathode, such that the reducible fuel species are reduced and electrodeposited as the metal fuel in oxidizable form on the at least one permeable electrode body, whereby the electrodeposition causes growth of the metal fuel among the permeable electrode bodies such that the electrodeposited metal fuel establishes an electrical connection between the permeable electrode bodies.

12. The electrochemical cell system of claim 10, wherein the reducible species of the metal fuel comprises ions of zinc, iron, aluminum, magnesium, or lithium, and wherein the metal fuel is zinc, iron, aluminum, magnesium, or lithium.

13. The electrochemical cell system of claim 1, wherein the ionically conductive medium comprises an aqueous electrolyte solution.

14. The electrochemical cell system of claim 13, wherein the aqueous electrolyte solution comprises sulfuric acid, phosphoric acid, triflic acid, nitric acid, potassium hydroxide, sodium hydroxide, sodium chloride, potassium nitrate, or lithium chloride.

15. The electrochemical cell system of claim 1, wherein each electrochemical cell has an associated said housing.

16. A method for assembling an electrochemical cell system comprising:

providing a cell module configured to receive a liquid ionically conductive medium therein;

installing a fuel electrode configured to store a metal fuel therein into a cell chamber of the cell module;

providing a plate for the cell module;

installing an oxidant electrode and a gas permeable and liquid impermeable membrane on the plate; and

joining the plate and the cell module such that the ionically conductive medium is prevented from permeating therebetween, and the oxidant electrode is spaced from the fuel electrode;

wherein the fuel electrode and the oxidant electrode are configured to, during discharge, oxidize the metal fuel at the fuel electrode and reduce an oxidant at the oxidant electrode to generate a discharge potential difference therebetween for application to a load; and

wherein the gas permeable and liquid impermeable membrane is positioned along a portion of the cell module and configured to close the portion of the cell module to contain the ionically conductive medium therein but permit gas in the cell module to permeate therethrough for venting of the gas from the electrochemical cell system.

17. The method of claim 16, wherein the gas permeable and liquid impermeable membrane comprises a fluoropolymer material

18. The method of claim 17, wherein the fluoropolymer material comprises polytetrafluoroethylene.

19. The method of claim 16, wherein the cell module contains a flow path for the liquid ionically conductive medium therein, the flow path being configured to facilitate a flow of the ionically conductive medium through the electrochemical cell system.

20. The method of claim 19, wherein the gas permeable and liquid impermeable membrane is positioned down the flow path from the fuel electrode and the oxidant electrode, and configured to receive gases generated during electrochemical reactions at the fuel and oxidant electrodes.

21. The method of claim 19, wherein the gas permeable and liquid impermeable membrane is configured to contact the ionically conductive medium while it flows through the flow path.

22. The method of claim 16, wherein a portion of the gas permeable and liquid impermeable membrane comprises the oxidant electrode.

23. The method of claim 16, further comprising providing a charging electrode selected from the group consisting of (a) the oxidant electrode, (b) a separate charging electrode spaced from the fuel and oxidant electrodes, and (c) a portion of the fuel electrode.

24. The method of claim 23, wherein the fuel electrode and the charging electrode are configured to, during re-charge, reduce a reducible species of the metal fuel to electrodeposit the metal fuel on the fuel electrode and oxidize an oxidizable species of the oxidant by application of a re-charge potential difference therebetween from a power source.

25. The method of claim 24, wherein the fuel electrode comprises a series of permeable electrode bodies arranged in spaced apart relation;

wherein the spaced apart relation of the permeable electrode bodies enables the re-charge potential difference to be applied between the charging electrode and at least one of the permeable electrode bodies, with the charging electrode functioning as the anode and the at least one permeable electrode body functioning as the cathode, such that the reducible fuel species are reduced and electrodeposited as the metal fuel in oxidizable form on the at least one permeable electrode body, whereby the electrodeposition causes growth of the metal fuel among the permeable electrode bodies such that the electrodeposited metal fuel establishes an electrical connection between the permeable electrode bodies.

26. The method of claim 24, wherein the reducible species of the metal fuel comprises ions of zinc, iron, aluminum, magnesium, or lithium, and wherein the metal fuel is zinc, iron, aluminum, magnesium, or lithium.

27. The method of claim 16, wherein the ionically conductive medium comprises an aqueous electrolyte solution.

28. The method of claim 27, wherein the aqueous electrolyte solution comprises sulfuric acid, phosphoric acid, triflic acid, nitric acid, potassium hydroxide, sodium hydroxide, sodium chloride, potassium nitrate, or lithium chloride.

29. An electrochemical cell system comprising:

a housing;

one or more electrochemical cells positioned within the housing, each comprising;

(i) a fuel electrode comprising a metal fuel; and

(ii) an oxidant electrode spaced from the fuel electrode;

a gas permeable and liquid impermeable membrane positioned to define a portion of a surface of the housing;

a liquid ionically conductive medium, within the housing, for conducting ions between the fuel and oxidant electrodes to support electrochemical reactions at the fuel and oxidant electrodes;

wherein the fuel electrode and the oxidant electrode are configured to, during discharge, oxidize the metal fuel at the fuel electrode and reduce an oxidant at the oxidant electrode to generate a discharge potential difference therebetween for application to a load; and

wherein the gas permeable and liquid impermeable membrane is configured to prevent permeation of the ionically conductive medium out of the housing, but permit gas in the housing to permeate therethrough for venting of the gas from the one or more electrochemical cells.

30. An oxidant electrode and vent assembly for an electrochemical cell comprising:

a gas permeable and liquid impermeable membrane; and

one or more oxidant electrode active materials provided on a first portion of the gas permeable and liquid impermeable membrane, but not a second portion of the gas permeable and liquid impermeable membrane;

wherein when the oxidant electrode and vent assembly is mounted to an electrochemical cell comprising a fuel electrode and a liquid ionically conductive medium such that the liquid ionically conductive medium contacts the one or more oxidant electrode active materials and the fuel electrode, the fuel electrode and the one or more oxidant electrode active materials are configured to, during discharge, oxidize the metal fuel at the fuel electrode and reduce a gaseous oxidant received through the gas-permeable and liquid impermeable membrane at the one or more oxidant electrode active materials, to generate a discharge potential difference therebetween for application to a load;

wherein at least the first portion of the gas permeable and liquid impermeable membrane is configured to prevent permeation of the ionically conductive medium out of the electrochemical cell and permit the gaseous oxidant to permeate into the one or more oxidant electrode active materials; and

wherein at least the second portion of the gas permeable and liquid impermeable membrane is configured to permit gas in the electrochemical cell to permeate therethrough for venting of the gas from the electrochemical cell, and prevent permeation of the ionically conductive medium out of the electrochemical cell.