ALKALINE MEMBRANE FUEL CELLS AND APPARATUS AND METHODS FOR SUPPLYING WATER THERETO

• US 20110151342A1
• Filed: 02/03/2011
• Published: 06/23/2011
• Est. Priority Date: 06/04/2008
• Status: Active Grant

• Current Assignee: Hydrolite Limited
• Original Assignee: Cellera, Inc.
• Inventors: Dekel, Dario, Simakov, David Stanislav, Gottesfeld, Ziv, Gottesfeld, Shimshon
• Granted Patent: US 8,257,872 B2
• Time in Patent Office: Days
• US Class Current: 429/414
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/8807 Gas diffusion layers
• CPC Class Codes: H01M 4/881 Electrolytic membranes
• CPC Class Codes: H01M 4/8825 Methods for deposition of the catalytic active composition
• CPC Class Codes: H01M 4/8853 Electrodeposition
• CPC Class Codes: H01M 4/886 Powder spraying, e.g. wet or dry powder spraying, plasma spraying
• CPC Class Codes: H01M 4/8871 Sputtering
• CPC Class Codes: H01M 4/8892 Impregnation or coating of the catalyst layer, e.g. by an ionomer
• CPC Class Codes: H01M 8/023 Porous and characterised by the material
• CPC Class Codes: H01M 8/0289 Means for holding the electrolyte solid polymer electrolytes H01M8/1018
• CPC Class Codes: H01M 8/083 Alkaline fuel cells
• CPC Class Codes: H01M 8/103 having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh]
• CPC Class Codes: H01M 8/106 characterised by the chemical composition of the porous support
• CPC Class Codes: H01M 8/1062 characterised by the physical properties of the porous support, e.g. its porosity or thickness
• CPC Class Codes: H01M 8/1067 characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
• CPC Class Codes: H01M 8/1088 Chemical modification, e.g. sulfonation
• CPC Class Codes: H01M 8/1093 mechanical, e.g. pressing, puncturing
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A device to produce electricity by a chemical reaction without the addition of liquid electrolyte comprises an anode electrode, a polymer membrane electrolyte fabricated to conduct hydroxyl (OH—) ions, the membrane being in physical contact with the anode electrode on a first side of the membrane, and a cathode electrode in physical contact with a second side of the membrane. The anode electrode and cathode electrode contain catalysts, and the catalysts are constructed substantially entirely from non-precious metal catalysts. Water may be transferred to the cathode side of the membrane from an external source of water.

Claims

1. An alkaline membrane fuel cell, the fuel cell comprising:

an anode electrode;

a polymer membrane electrolyte configured to conduct hydroxyl (OH—

) ions, the membrane being in physical contact with the anode electrode on a first side of the membrane; and

a cathode electrode in physical contact with a second opposite side of the membrane;

wherein the fuel cell is configured and disposed with a substantially dead ended anode chamber and is configured to transfer water from the anode electrode through the membrane to the cathode electrode at a rate substantially equivalent to water generation at the anode electrode.

2. The fuel cell of claim 1 wherein water transport across the membrane is facilitated by a highly hydrophilic membrane or mesh shaped and placed as a frame around the active area on both the anode and cathode sides.

3. The fuel cell of claim 1, further comprising a mixed hydrophilic/hydrophobic microporous layer proximate to the anode electrode and a gas diffusion layer proximate to the microporous layer.

4. The fuel cell of claim 1, further comprising a hydrophobic microporous layer proximate to the cathode electrode and a gas diffusion layer proximate to the microporous layer.

5. The fuel cell of claim 4, when operating in air breathing mode, further comprising an adjustable shutter proximate to the gas diffusion layer.

6. The fuel cell of claim 4 when operating in air breathing mode with the cathode GDL thickness and porosity designed for a water vapor rate of release matching a selected cell current, Jcell and inner cell temperature, Tcell according to the equation:

P*_H2O,Tcell=0.4 [J_{cell/Jlim,cath}]atm., where P*_H2O,Tcell is the water vapor pressure at Tcell and Jlim,cath is the limiting current corresponding to the max. transport rate of oxygen from air through the GDL.

7. The fuel cell of claim 1 wherein initial activation of the cell achieved by setting the cell voltage at about or near 50 mV and keeping it at this voltage until the cell current plateaus while the cell temperature reaches a target operation temperature.

8. The fuel cell of claim 7 wherein the current plateaus near 1 A/cm2 and the cell operation temperature is between 60 and 70 degrees Celsius.

9. The fuel cell of claim 1, wherein the substantially dead-ended anode further includes a one-way valve, the one-way valve opening periodically to the ambient by internal pressure buildup and possible temporary use of high flow of hydrogen to periodically purge water buildup.

10. The fuel cell of claim 1 wherein direct supply of liquid water to the cathode side of the membrane is provided by means of a water channel about 1 millimeter wide surrounding an active area of the fuel cell.

11. The fuel cell of claim 10 wherein water transfer from the water channel to and along the membrane surface is facilitated by a wicking mesh incorporated as part of the membrane on the side adjacent the cathode catalyst.

12. The fuel cell of claim 11 wherein the wicking mesh is incorporated to become an integral part of the membrane by placing it along the major surface of the membrane during membrane casting.

13. The fuel cell of claim 11 wherein the wicking mesh is attached onto the surface of a pre-fabricated membrane by using a solution of an ionomer to fill spaces in the mesh and to provide a bonding function following subsequent ionomer recasting.

14. The fuel cell of claim 10 wherein the liquid water supply to the cathode side of the membrane is provided from a stationary reservoir of liquid water with the water wicked from such reservoir into and along the cathode side of the membrane.

17. A fuel cell stack built by stacking a plurality of cells of the type recited in the device of claim 1 wherein bipolar plates separating adjacent cells are constructed of machined aluminum coated by a film of nickel applied by electroless plating.

18. The device of claim 17 wherein the aluminum plate metal is aluminum alloy designated as alloy number 6061.

19. The device of claim 17 wherein the nickel coat thickness is greater than about 1 micrometer, preferably about 25 micrometers.

15. An alkaline membrane fuel cell comprising:

an anode electrode;

a polymer membrane electrolyte configured to conduct hydroxyl (OH—

) ions, the membrane being in physical contact with the anode electrode on a first side of the membrane;

a cathode electrode in physical contact with a second opposite side of the membrane;

wherein the fuel cell is configured and designed to transfer water from the anode electrode through the membrane to the cathode electrode;

further comprising a water exchanger operatively connected with the fuel cell and disposed to exchange water from the cathode electrode exhaust stream to the cathode electrode inlet stream.

16. The device of claim 15 wherein the water exchanger includes a membrane, the membrane being of high water permeability and low gas permeability to enable transport of water from the humidified cathode electrode exhaust stream to an inlet stream of dry air.