Method for reducing degradation in a fuel cell

1. A method of reducing catalyst dissolution in the cathode of a membrane electrode assembly fuel cell, said method comprising the steps of:

a. preparing a membrane electrode assembly comprising an anode, a cathode and a polymer electrolyte membrane interposed between said anode and said cathode;

b. assembling a fuel cell using said membrane electrode assembly;

c. applying a fluid comprising an oxidant to said cathode of said membrane electrode assembly;

d. applying a fluid comprising a fuel to said anode of said membrane electrode assembly; and

e. supplying a sufficient quantity of reducing agent different from said fluid comprising an oxidant to said cathode to maintain the average open-circuit voltage of said cathode at less than about 0.98 V.

2. The method of claim 1 wherein said average open-circuit voltage of said cathode is less than about 0.95 V.

3. The method of claim 2 wherein the operation of said fuel cell is at temperatures between about 85 and 150 degrees Centigrade.

4. The method of claim 3 wherein said temperature is about 90 degrees Centigrade.

5. The method of claim 3 wherein said temperature is about 100 degrees Centigrade.

6. The method of claim 3 wherein said temperature is about 110 degrees Centigrade.

7. The method of claim 3 wherein said temperature is about 120 degrees Centigrade.

8. The method of claim 1 wherein said average open-circuit voltage of said cathode is less than about 0.90 V.

9. The method of claim 1 wherein said sufficient quantity of reducing agent supplied to said cathode is supplied to said fluid comprising an oxidant.

10. The method of claim 9 wherein said sufficient quantity of reducing agent supplied to said fluid comprising an oxidant is supplied from an external source.

11. The method of claim 10 wherein the said sufficient quantity of reducing agent supplied to said cathode comprises hydrogen gas.

12. The method of claim 9 wherein said sufficient quantity of reducing agent supplied to said fluid comprising an oxidant is supplied from an internal source.

13. The method of claim 12 wherein said internal source comprises gas that crosses over from said fluid comprising a fuel supplied to said anode.

14. The method of claim 1 wherein said polymer electrolyte membrane comprises perfluorosulfonic acid and optionally expanded polytetrafluoroethylene.

15. The method of claim 1 wherein said reducing agent supplied to said cathode comprises a solid that has a standard oxidation potential less than Pt and greater than hydrogen.

16. The method of claim 15 wherein said solid is selected from the group consisting of noble metals.

17. The method of claim 16 wherein said solid is selected from the group consisting of Cu, Ag, Pd, Os, Ru and Ir.

18. A fuel cell comprising an anode, a cathode, a polymer electrolyte membrane interposed between said anode and said cathode, means for applying a fluid comprising an oxidant to said cathode, means for applying a fluid comprising a fuel to said anode, and means for supplying a sufficient quantity of reducing agent different from said fluid comprising an oxidant to said fluid comprising an oxidant to maintain the average open-circuit voltage of said cathode at less than about 0.98 V.

19. A fuel cell as defined in claim 18 wherein said polymer electrolyte membrane has a thickness less than about 12 microns.

20. A fuel cell as defined in claim 18 wherein said polymer electrolyte membrane has a thickness less than about 8 microns.

21. A fuel cell as defined in claim 18 wherein said cathode comprises a platinum catalyst.

22. A fuel cell as defined in claim 18 wherein said platinum catalyst has a loading of less than about 0.1 mg/cm 2 .

23. A fuel cell as defined in claim 18 wherein said polymer electrolyte membrane further comprises a perfluorosulfonic acid and optionally expanded polytetrafluoroethylene.

24. A method of operating a fuel cell comprising the steps of:

a. preparing a membrane electrode assembly comprising an anode, a cathode and a polymer electrolyte membrane interposed between said anode and said cathode;

b. assembling a fuel cell using said membrane electrode assembly;

c. applying a fluid comprising an oxidant to said cathode of said membrane electrode assembly;

d. applying a fluid comprising a fuel to said anode of said membrane electrode assembly; and

e. supplying a sufficient quantity of reducing agent different from said fluid comprising an oxidant to said cathode to maintain the average open-circuit voltage of said cathode at less than about 0.98 V.

25. The method of claim 24 wherein said average open-circuit voltage of said cathode is less than about 0.95 V.

26. The method of claim 25 wherein said average open-circuit voltage of said cathode is less than about 0.90 V.

27. The method of claim 24 wherein the operation of said fuel cell is at temperatures between about 85 and 150 degrees Centigrade.

28. The method of claim 24 wherein said sufficient quantity of reducing agent supplied to said cathode is supplied to said fluid comprising an oxidant.

29. The method of claim 28 wherein said sufficient quantity of reducing agent supplied to said fluid comprising an oxidant is supplied from an external source.

30. The method of claim 29 wherein the said sufficient quantity of reducing agent supplied to said cathode comprises hydrogen gas.

31. The method of claim 28 wherein said sufficient quantity of reducing agent supplied to said fluid comprising an oxidant is supplied from an internal source.

32. The method of claim 31 wherein said internal source comprises gas that crosses over from said fluid comprising a fuel supplied to said anode.

33. The method of claim 24 wherein said polymer electrolyte membrane comprises perfluorosulfonic acid and optionally expanded polytetrafluoroethylene.