Direct methanol fuel cell system and method of fabrication

• US 6,387,559 B1
• Filed: 07/18/2000
• Issued: 05/14/2002
• Est. Priority Date: 07/18/2000
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ooms, William J., Wilcox, David L., Bostaph, Joseph W., Koripella, Chowdary Ramesh
• Primary Examiner(s): Maples, John S.
• Application Number:
  US09/618,399
• Time in Patent Office: 665 Days
• Field of Search: 429/34, 429/30, 429/33, 429/19, 429/22
• US Class Current: 429/410
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/04186 of liquid-charged or electrolyte-charged reactants
• CPC Class Codes: H01M 8/1009 with one of the reactants being liquid, solid or liquid-charged H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1097 Fuel cells applied on a support, e.g. miniature fuel cells deposited on silica supports
• CPC Class Codes: H01M 8/2455 with liquid, solid or electrolyte-charged reactants
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A fuel cell system and method of forming the fuel cell system including a base portion, formed of a singular body, and having a major surface. At least one fuel cell membrane electrode assembly is formed on the major surface of the base portion. A fluid supply channel including a mixing chamber is defined in the base portion and communicating with the fuel cell membrane electrode assembly for supplying a fuel-bearing fluid to the membrane electrode assembly. An exhaust channel including a water recovery and recirculation system is defined in the base portion and communicating with the membrane electrode assembly. The membrane electrode assembly and the cooperating fluid supply channel and cooperating exhaust channel forming a single fuel cell assembly.

Claims

1. A fuel cell system comprising:

a base portion, formed of a singular body, and having a major surface;

at least one fuel cell membrane electrode assembly formed on the major surface of the base portion;

a fluid supply channel defined in the base portion and communicating with the at least one fuel cell membrane electrode assembly, the fluid supply channel including a mixing chamber and at least two fuel-bearing fluid inlets for the inlet of a fuel-beating fluid; and

an exhaust channel defined in the base portion and communicating with the at least one fuel cell membrane electrode assembly, the exhaust channel including a water recovery and recirculation system, the exhaust channel spaced apart from the fluid supply channel for exhausting fluid from the at least one fuel cell membrane electrode assembly, the at least one fuel cell membrane electrode assembly and the cooperating fluid supply channel and cooperating exhaust channel forming a single fuel cell assembly.

2. A fuel cell system as claimed in claim 1 wherein the base portion comprises a material selected from the group consisting of ceramic, plastic, glass, and silicon.

3. A fuel cell system as claimed in claim 2 further wherein the at least one fuel cell membrane electrode assembly formed on the major surface of the base portion includes a plurality of fuel cell membrane electrode assemblies formed on the major surface of the base portion wherein each of the plurality of fuel cell membrane electrode assemblies is spaced at least 1 mm from an adjacent fuel cell membrane electrode assembly.

4. A fuel cell system as claimed in claim 1 wherein the fuel cell membrane electrode assembly includes a first electrode, a film adjacent the first electrode, formed of a protonically conductive electrolyte, and a second electrode in contact with the film.

5. A fuel cell system as claimed in claim 4 wherein the first and second electrodes comprise a material selected from the group consisting of platinum, palladium, gold, nickel, tungsten carbide, ruthenium, molybdenum, and alloys of platinum, palladium gold, nickel, tungsten carbide, molybdenum, and ruthenium.

6. A fuel cell system as claimed in claim 5 wherein the film adjacent the first electrode is comprised of a proton exchange type material.

7. A fuel cell system as claimed in claim 1 wherein (the fuel-bearing fluid) is comprised of mixture of methanol and water, supplied by a separate methanol source and a separate water source, and mixed in-situ.

8. A fuel cell system as claimed in claim 1 wherein the fluid supply channel defined in the base portion and communicating with the fuel cell membrane electrode assembly includes a methanol concentration sensor.

9. A fuel cell system as claimed in claim 1 wherein the exhaust channel defined in the base portion and communicating with the fuel cell membrane electrode assembly further includes a carbon dioxide separation chamber and a carbon dioxide exhaust vent.

10. A fuel cell system as claimed in claim 1 wherein the water recovery and recirculation system provides for the recovery and recirculation of a spent water and ethanol mixture from the fuel cell back to the mixing chamber.

11. A fuel cell array apparatus comprising:

a base portion, formed of a singular body, and having a major surface, the base portion formed of a material selected from the group consisting of ceramic, plastic, glass, and silicon;

at least one fuel cell membrane electrode assembly formed on the major surface of the base portion, the at least one fuel cell membrane electrode assembly including a first electrode, a film in contact with the first electrode and formed of a protonically conductive electrolyte, and a second electrode in contact with the film;

a fluid supply channel defined in the base portion and communicating with the at least one fuel cell membrane electrode assembly for supplying a fuel-bearing fluid to the at least one fuel cell membrane electrode assembly, the fluid supply channel further including a first fuel-bearing fluid inlet, and a second fuel-bearing fluid inlet, and a mixing chamber;

an exhaust channel defined in the base portion and communicating with the at least one fuel cell membrane electrode assembly, the exhaust channel spaced apart from the fluid supply channel for exhausting fluid from the at least one spaced apart fuel cell membrane electrode assembly, the exhaust channel further including a water recovery and recirculation assembly in fluidic communication with the send electrode of the at least one fuel cell membrane electrode assembly, in combination the at least one fuel cell membrane electrode assembly and the cooperating fluid supply channel and cooperating exhaust channel forming a single fuel cell assembly; and

a top portion for electrical integration of a plurality of fuel cell membrane electrode assemblies.

12. A fuel cell array apparatus as claimed in claim 11 further including a plurality of spaced apart fuel cell membrane electrode assemblies formed on the major surface of the base portion, thereby forming a plurality of fuel cell assemblies.

13. A fuel cell array apparatus as claimed in claim 12 wherein the plurality of fuel cell membrane electrode assemblies are electrically connected in one of a series electrical interface or a parallel electrical interface.

14. A fuel cell array apparatus as claimed in claim 13 wherein the fluid supply channel defined in the base portion and the exhaust channel defined in the base portion are formed to equally and simultaneously communicate with each of the plurality of spaced apart fuel cell membrane electrode assemblies.

15. A fuel cell array apparatus as claimed in claim 11 wherein the first and second electrodes comprise a material selected from the group consisting of platinum, palladium, gold, nickel, tungsten carbide, molybdenum, ruthenium, and alloys of platinum, palladium, gold, nickel, tungsten carbide, molybdenum, and ruthenium.

16. A fuel cell array apparatus as claimed in claim 11 wherein the fluid supply channel defined in the base portion includes a methanol concentration sensor.

17. A fuel cell array apparatus as claimed in claim 11 wherein the exhaust channel defined in the base portion includes a carbon dioxide separation chamber and a carbon dioxide exhaust vent.

18. A method of fabricating a fuel cell array apparatus comprising the steps of:

providing a base portion formed of a material selected from the group consisting of ceramic, plastic, glass, and silicon;

forming a fluid supply channel in the base portion for supplying a fuel-bearing fluid to at least one fuel cell membrane electrode assembly, the fluid supply channel further including a mixing Her and a methanol concentration sensor;

forming an exhaust channel in the base portion, the exhaust spaced apart from the fluid supply channel for exhausting fluid from the at least one spaced apart fuel cell membrane electrode assembly, the exhaust channel further including a water recovery and recirculation system for the recover and recirculation of a spent fuel-bearing fluid;

forming the at least one fuel cell membrane electrode assembly on the major surface of the base portion, the step of forming the at least one spaced apart fuel cell membrane electrode assembly including the steps of providing for a first electrode on a major surface of the base portion, providing for a film in contact with the first electrode and formed of a protonically conductive electrolyte, and providing for a second electrode in contact with the film the at least one spaced apart fuel cell membrane electrode assembly and the cooperating fluid supply channel and cooperating exhaust channel forming a single fuel cell assembly; and

forming a top portion for electrical integration of a plurality of fuel cell membrane electrode assemblies.

19. A method of fabricating a fuel cell array apparatus as claimed in claim 18 wherein the step of forming the at least one fuel cell membrane electrode assembly on the major surface of the base portion includes the step of forming a plurality of fuel cell membrane electrode assemblies.

20. A method of fabricating a fuel cell array apparatus as claimed in claim 18 further including the step of electrically interfacing the plurality of fuel cell membrane electrode assemblies including one of the steps of electrically connecting each of the second electrodes to an adjacent first electrode, thus connecting the plurality of fuel cells in series electrically to increase the output voltage of the structure or electrically connecting each of the first electrodes to an adjacent first electrode and connecting each of the second electrodes to an adjacent second electrode, thus connected in parallel electrically to increase tie output current.