Method and apparatus for providing a uniform fuel cell stack structure

• US 20030203269A1
• Filed: 04/30/2002
• Published: 10/30/2003
• Est. Priority Date: 04/30/2002
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Rock, Jeffrey A.
• Granted Patent: US 7,045,245 B2
• Time in Patent Office: Days
• US Class Current: 429/37
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 8/2475 Enclosures, casings or containers of fuel cell stacks
• CPC Class Codes: H01M 8/248 Means for compression of the fuel cell stacks
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An electro-chemical fuel cell stack has a plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly. The fuel cell assembly is interposed between at least one spacer plate and first and second end plates. The first and second end plates are held in a fixed spaced relation so that the first and second end plates impart a compressive force on the fuel cell assembly. The spacer plates can be used to provide a fuel cell stack of a predetermined length. The fuel cell stack can be made by compressing the fuel cell stack with a predetermined compressive load or by compressing the fuel cell stack a predetermined distance and then securing the first and second end plates in a fixed spaced relation.

Claims

1. An electrochemical fuel cell stack, the stack comprising:

a plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly, said fuel cell assembly having opposite first and second ends and a length therebetween;

first and second end plates, said first and second end plates being respectively disposed adjacent said first and second ends of said fuel cell assembly, and said first and second end plates being held in a fixed spaced relation of a predetermined distance so that said first and second end plates impart a compressive force on said fuel cell assembly along said length; and

at least one spacer plate interposed between said first end plate and said first end of said fuel cell assembly, said at least one spacer plate being dimensioned so that said compressive force imparted on said fuel cell assembly by said first and second end plates is of a predetermined magnitude.

2. The stack of claim 1, wherein said at least one spacer plate has a plurality of openings so that said at least one spacer plate has a reduced weight.

3. The stack of claim 1, wherein said at least one spacer plate is electrically non-conductive.

4. The stack of claim 3, further comprising a terminal plate interposed between said at least one spacer plate and said first end of said fuel cell assembly, said at least one spacer plate separating said terminal plate from said first end plate to electrically insulate said terminal plate from said first end plate.

5. The stack of claim 1, wherein said first end of said fuel cell assembly is a dry end of said fuel cell assembly.

6. The stack of claim 1, further comprising a plurality of spacer plates, each spacer plate of said plurality of spacer plates is positioned between at least one of said first and second end plates and said fuel cell assembly.

7. The stack of claim 1, wherein said at least one spacer plate is plastic.

8. A method of making an electro-chemical fuel cell stack of a predetermined length, the method comprising the steps of:

choosing a predetermined length for a fuel cell stack having a fuel cell assembly;

compressing said fuel cell assembly with a predetermined compressive load;

determining a compressed length of said compressed fuel cell assembly;

calculating a difference between a length of space available for said compressed fuel cell assembly in said fuel cell stack and said compressed length of said compressed fuel cell assembly;

removing said predetermined compressive load from said fuel cell assembly;

positioning at least one spacer plate having a thickness generally equal to said calculated difference in said fuel cell stack;

applying a compressive load to said fuel cell stack so that said fuel cell stack is compressed to said predetermined length;

securing first and second end plates of said fuel cell stack in a fixed spaced relation to retain said fuel cell stack at said predetermined length, thereby imparting a compressive force on said fuel cell assembly after said applied compressive load on said fuel cell stack is removed; and

removing said applied compressive load from said fuel cell stack.

9. The method of claim 8, wherein the step of determining a compressed length of said compressed fuel cell assembly includes measuring said compressed length of said compressed fuel cell assembly.

10. The method of claim 8, wherein the step of compressing said fuel cell assembly includes compressing said fuel cell stack with said predetermined compressive load.

11. The method of claim 10, wherein the step of determining a compressed length of said compressed fuel cell assembly includes measuring said compressed length of said compressed fuel cell assembly.

12. The method of claim 10, wherein the step of determining a compressed length of said compressed fuel cell assembly includes measuring a length of said compressed fuel cell stack and calculating said compressed length of said fuel cell assembly.

13. The method of claim 8, wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a dry end of said fuel cell assembly and an end plate adjacent said dry end of said fuel cell assembly.

14. The method of claim 8, wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a terminal plate adjacent at least one of first and second end plates and said fuel cell assembly.

15. The method of claim 8, wherein the step of securing first and second end plates of said fuel cell stack in a fixed spaced relation includes attaching at least one side plate to said first and second end plates of said fuel cell stack.

16. A method of making an electrochemical fuel cell stack of a predetermined length, the method comprising the steps of:

choosing a predetermined length for a fuel cell stack having a fuel cell assembly;

compressing said fuel cell stack with a predetermined compressive load;

determining a compressed length of said compressed fuel cell stack;

calculating a difference between said predetermined length and said compressed length of said compressed fuel cell stack;

removing said predetermined compressive load from said fuel cell stack;

positioning at least one spacer plate having a thickness generally equal to said calculated difference in said fuel cell stack;

applying a compressive load to said fuel cell stack so that said fuel cell stack is compressed to said predetermined length;

securing first and second end plates of said fuel cell stack in a fixed spaced relation to retain said fuel cell stack at said predetermined length, thereby imparting a compressive force on said fuel cell assembly after said applied compressive load on said fuel cell stack is removed; and

removing said applied compressive load from said fuel cell stack.

17. The method of claim 16, wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a dry end of said fuel cell assembly and an end plate adjacent said dry end of said fuel cell assembly.

18. The method of claim 16, wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a terminal plate adjacent at least one of said first and second end plates and said fuel cell assembly.

19. The method of claim 16, wherein the step of securing first and second end plates of said fuel cell stack in a fixed spaced relation includes attaching at least one side plate to said first and second end plates of said fuel cell stack.

20. A method of making an electro-chemical fuel cell stack of the type having a plurality of fuel cells in a fuel cell assembly, the method comprising the steps of:

determining a predetermined distance to compress a fuel cell stack having a fuel cell assembly to impart a compressive force of a predetermined magnitude on said fuel cell assembly;

applying a compressive load to said fuel cell stack so that said fuel cell stack is compressed said predetermined distance;

securing first and second end plates of said fuel cell stack in a fixed spaced relation so that said first and second end plates retain said fuel cell stack compressed to said predetermined distance thereby imparting a compressive force of said predetermined magnitude on said fuel cell assembly after said compressive load is removed; and

removing said compressive load from said fuel cell stack.

21. The method of claim 20, wherein the step of determining a predetermined distance to compress a fuel cell stack includes determining said predetermined distance to compress said fuel cell stack based upon a known quantity of fuel cells in said fuel cell assembly.

22. The method of claim 21, wherein the step of determining a predetermined distance to compress a fuel cell stack includes determining said predetermined distance to compress said fuel cell stack by multiplying said known quantity of fuel cells by a fixed distance of compression.

23. The method of claim 21, wherein the step of determining a predetermined distance to compress a fuel cell stack includes the steps of:

collecting empirical data from fuel cell stacks that have been previously compressed with known compressive loads to impart a desired compressive load to be imparted upon said fuel cell stack; and

determining said predetermined distance to compress said fuel cell stack by selecting said predetermined distance based upon said empirical data.

24. The method of claim 20, wherein the step of determining a predetermined distance to compress a fuel cell stack includes the steps of:

determining a compressed distance to compress said fuel cell assembly; and

calculating said predetermined distance to compress said fuel cell stack based upon said compressed distance to compress said fuel cell assembly.

25. The method of claim 24, wherein the step of determining a compressed distance to compress said fuel cell assembly includes determining said distance to compress said fuel cell assembly based upon a known quantity of fuel cells in said fuel cell assembly.

26. The method of claim 25, wherein the step of determining a distance to compress said fuel cell assembly includes determining said distance to compress said fuel cell assembly by multiplying said known quantity of fuel cells by a fixed distance of compression.

27. The method of claim 25, wherein the step of determining a predetermined distance to compress said fuel cell assembly includes the steps of:

collecting empirical data from fuel cell stacks that have been previously compressed with known compressive loads to impart a desired compressive load to be imparted upon said fuel cell stack; and

determining said distance to compress said fuel cell assembly by selecting said distance based upon said empirical data.

28. A method of making a fixed length fuel cell stack of the type having a plurality of fuel cells in a fuel cell assembly, the method comprising the steps of:

choosing a predetermined length for a fuel cell stack having a fuel cell assembly;

determining a predetermined distance to compress a fuel cell stack having a fuel cell assembly to impart a compressive force of a predetermined magnitude on said fuel cell assembly;

calculating a spacer plate thickness as a function of said predetermined length and said predetermined distance;

positioning at least one spacer plate having said spacer plate thickness in said fuel cell stack;

applying a compressive load to said fuel cell stack so that said fuel cell stack is compressed to generally said predetermined length;

securing first and second end plates of said fuel cell stack in a fixed spaced relation so that said first and second end plates retain said fuel cell stack compressed to said predetermined length, thereby imparting a compressive force of said generally known magnitude on said fuel cell assembly after said compressive load is removed; and

removing said compressive load from said fuel cell stack.

29. The method of claim 28, wherein the step of calculating a spacer plate thickness includes calculating a spacer plate thickness based on a compressed length of said fuel cell assembly when said fuel cell stack is compressed said predetermined distance.

30. The method of claim 29, wherein the step of calculating a spacer plate thickness includes subtracting said compressed length of said fuel cell assembly and a thickness of said first and second end plates from said predetermined length to determine said spacer plate thickness.

31. The method of claim 28, wherein the step of determining a predetermined distance to compress a fuel cell stack includes determining said predetermined distance to compress said fuel cell stack based upon a known quantity of fuel cells in said fuel cell assembly.

32. The method of claim 31, wherein the step of determining a predetermined distance to compress a fuel cell stack includes determining said predetermined distance to compress said fuel cell stack by multiplying said known quantity of fuel cells by a fixed distance.

33. The method of claim 31, wherein the step of determining a predetermined distance to compress a fuel cell stack includes the steps of:

collecting fuel cell stacks that have been previously compressed with known compressive loads to impart a desired compressive load upon said fuel cell stack; and

determining said predetermined distance to compress said fuel cell stack by selecting said predetermined distance based upon said empirical data.

34. The method of claim 28, wherein the step of determining a predetermined distance to compress a fuel cell stack includes the steps of:

determining a compressed distance to compress said fuel cell assembly; and

calculating said predetermined distance to compress said fuel cell stack based upon said compressed distance to compress said fuel cell assembly.

35. The method of claim 34, wherein the step of determining a compressed distance to compress said fuel cell assembly includes determining said distance to compress said fuel cell assembly based upon a known quantity of fuel cells in said fuel cell assembly.

36. The method of claim 35, wherein the step of determining a compressed distance to compress said fuel cell assembly includes determining said distance to compress said fuel cell assembly by multiplying said known quantity of fuel cells by a fixed distance of compression.

37. The method of claim 35, wherein the step of determining a distance to compress said fuel cell assembly includes the steps of:

collecting empirical data from fuel cell stacks that have been previously compressed with known compressive loads to impart a desired compressive load upon said fuel cell stack; and

determining said distance to compress said fuel cell assembly by selecting said distance based upon said empirical data.