Polymer electrolyte membrane fuel cell system

• US 20050069735A1
• Filed: 08/06/2004
• Published: 03/31/2005
• Est. Priority Date: 02/06/2002
• Status: Abandoned Application

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Vijayendran, Bhima R., Saunders, James H., George, Paul E. II
• Application Number:
  US10/913,293
• Publication Number:
  US 20050069735A1
• Time in Patent Office: Days
• US Class Current: 429/412
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/04992 characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence
• CPC Class Codes: H01M 8/0612 from carbon-containing material
• CPC Class Codes: H01M 8/0668 Removal of carbon monoxide or carbon dioxide
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1011 Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

The invention also relates to a fuel cell system comprising: a fuel processor for producing hydrogen from a fuel; and a fuel cell stack including a plurality of polymer electrolyte membranes and a plurality of electrodes; where the polymer electrolyte membrane comprises a proton conducting hydrocarbon-based polymer membrane, the polymer having a backbone and having acidic groups on side chains attached to the backbone. The invention also relates to methods of removing contaminants from the fuel cell electrode.

Claims

1. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts;

apparatus to provide a fuel to the fuel cells; and

a method of optimizing a waveform of an electrical current applied to the electrodes, comprising the steps of;

applying an electrical current to the electrodes;

determining a waveform of the voltage or the current of the electrical current;

representing the waveform by a mathematical description;

measuring a function of the fuel cells associated with the application of the electrical current;

feeding the waveform description and the measurements to an algorithm, including an optimization routine which uses the description to optimize the function of the fuel cells; and

performing calculations to determine values of the waveform description which optimize the function of the fuel cells, and thereby determine an optimized waveform of the electrical current to be applied to the electrodes of the fuel cells.

2. A fuel cell system according to claim 1 wherein the apparatus to provide fuel is a simplified fuel processor including a fuel reformer and excluding at least one of a water-gas shift reactor and a CO cleanup reactor.

3. A fuel cell system according to claim 1 wherein the polymer electrolyte membranes can operate at temperatures above 100°

C.

4. A fuel cell system according to claim 1 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the polymer having a backbone and having acidic groups on side chains attached to the backbone.

5. A fuel cell system according to claim 1 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the membranes comprising a basic material in combination with an acidic material selected from acidic hydrocarbon-based polymers, acidic hydrocarbon-based oligomers, and blends thereof.

6. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, anodes, cathodes, and catalysts;

apparatus to provide a fuel to the fuel cells; and

a method of removing contaminants from the anodes of the fuel cells, comprising;

applying an electrical current to the anodes; and

pulsing the voltage of the electrical current during the application, such that an overvoltage at the anodes is negative during the pulses, and the overvoltage at the anodes is positive between the pulses.

7. A fuel cell system according to claim 6 wherein the polymer electrolyte membranes can operate at temperatures above 100°

C.

8. A fuel cell system according to claim 6 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the polymer having a backbone and having acidic groups on side chains attached to the backbone.

9. A fuel cell system according to claim 6 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the membranes comprising a basic material in combination with an acidic material selected from acidic hydrocarbon-based polymers, acidic hydrocarbon-based oligomers, and blends thereof.

10. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts;

apparatus to provide a fuel to the fuel cells, the fuel containing at least one percent of an electrochemically active contaminant; and

a method of operating the fuel cells comprising applying an overvoltage to the electrodes of the fuel cells, and varying the overvoltage between a low value normally used for power production and a high value for cleaning the contaminant from the electrodes.

11. A fuel cell system according to claim 10 wherein the electrodes include anodes and cathodes, and wherein the overvoltage is applied to the anodes.

12. A fuel cell system according to claim 10 wherein the contaminant is CO.

13. A fuel cell system according to claim 10 wherein the polymer electrolyte membranes can operate at temperatures above 100°

C.

14. A fuel cell system according to claim 10 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the polymer having a backbone and having acidic groups on side chains attached to the backbone.

15. A fuel cell system according to claim 10 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the membranes comprising a basic material in combination with an acidic material selected from acidic hydrocarbon-based polymers, acidic hydrocarbon-based oligomers, and blends thereof.

16. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, anodes, cathodes, and catalysts;

apparatus to provide a fuel to the fuel cells, the fuel containing an electrochemically active contaminant; and

a feedback control method of operating the fuel cells comprising applying voltage control to the anodes using the following algorithm;

(a) determining a mathematical model that relates an instantaneous coverage of the fuel and an instantaneous coverage of the contaminant on the anodes to an overvoltage applied to the anodes;

(b) forming an observer that relates the instantaneous coverage of the fuel and the contaminant to a measured current of the fuel cells;

(c) driving an estimated contaminant coverage to a low value by varying the overvoltage;

(d) driving an estimated fuel coverage to a high value by varying the overvoltage; and

(e) repeating steps (a) through (d) as necessary.

17. A fuel cell system according to claim 16 wherein the contaminant is carbon monoxide at a level of greater than one percent in the hydrogen.

18. A fuel cell system according to claim 16 wherein the algorithm comprises the additional steps, between steps (b) and (c), of (b1) prescribing a desired trajectory of the instantaneous coverage of the fuel and the contaminant as a function of time, and (b2) forming a set of mathematical relationships from steps (a), (b) and (b1) that allows the current to be measured, the overvoltage to be prescribed, and the instantaneous contaminant coverage and the instantaneous fuel coverage to be estimated.

19. A fuel cell system according to claim 16 wherein the polymer electrolyte membranes can operate at temperatures above 100°

C.

20. A fuel cell system according to claim 16 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the polymer having a backbone and having acidic groups on side chains attached to the backbone.

21. A fuel cell system according to claim 16 wherein the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the membranes comprising a basic material in combination with an acidic material selected from acidic hydrocarbon-based polymers, acidic hydrocarbon-based oligomers, and blends thereof.

22. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts; and

apparatus to provide a fuel to the fuel cells;

where the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes, the polymer having a backbone and having acidic groups on side chains attached to the backbone.

23. A fuel cell system according to claim 22 wherein the polymer electrolyte membranes can operate at temperatures above 100°

C.

24. A fuel cell system according to claim 22 wherein the fuel is methanol.

25. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts; and

apparatus to provide a fuel to the fuel cells;

where the polymer electrolyte membranes comprise proton conducting membranes, the membranes comprising a basic material in combination with an acidic material selected from acidic hydrocarbon-based polymers, acidic hydrocarbon-based oligomers, and blends thereof.

26. A fuel cell system according to claim 25 wherein the polymer electrolyte membranes can operate at temperatures above 100°

C.

27. A fuel cell system according to claim 25 wherein the fuel is methanol.

28. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts; and

apparatus to provide a fuel to the fuel cells;

where the polymer electrolyte membranes comprise proton conducting hydrocarbon-based polymer membranes having a phase separated morphological microstructure.

29. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts; and

apparatus to provide a fuel to the fuel cells;

where the polymer electrolyte membranes comprise proton conducting membranes produced from a solid hydrocarbon-based polymer in combination with a gel hydrocarbon-based polymer, the solid and gel polymers having acidic groups.

30. A fuel cell system comprising:

a stack of fuel cells including a plurality of interleaved layers of polymer electrolyte membranes, electrodes, and catalysts; and

apparatus to provide a fuel to the fuel cells;

where the polymer electrolyte membranes comprise proton conducting membranes, the membranes comprising an epoxy-containing polymer in combination with a nitrogen-containing compound.