Micro fuel cell architecture

• US 20050014059A1
• Filed: 06/25/2004
• Published: 01/20/2005
• Est. Priority Date: 06/27/2003
• Status: Abandoned Application

• Current Assignee: UltraCell Corporation (Bren-Tronics, Inc.)
• Original Assignee: UltraCell Corporation (Bren-Tronics, Inc.)
• Inventors: Kaye, Ian W.
• Application Number:
  US10/877,824
• Publication Number:
  US 20050014059A1
• Time in Patent Office: Days
• US Class Current: 429/430
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2008/1293 Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 2300/0008 Phosphoric acid-based
• CPC Class Codes: H01M 8/0202 Collectors; Separators, e.g. bipolar separators; Interconnectors
• CPC Class Codes: H01M 8/0206 Metals or alloys
• CPC Class Codes: H01M 8/0215 Glass; Ceramic materials
• CPC Class Codes: H01M 8/0221 Organic resins; Organic polymers
• CPC Class Codes: H01M 8/0228 in the form of layered or coated products
• CPC Class Codes: H01M 8/0234 Carbonaceous material
• CPC Class Codes: H01M 8/0247 characterised by the form characterised by a channel configuration H01M8/0258
• CPC Class Codes: H01M 8/0258 characterised by the configuration of channels, e.g. by the flow field of the reactant or coolant
• CPC Class Codes: H01M 8/026 characterised by grooves, e.g. their pitch or depth
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/0273 with sealing or supporting means in the form of a frame
• CPC Class Codes: H01M 8/0297 Arrangements for joining electrodes, reservoir layers, heat exchange units or bipolar separators to each other H01M8/0271 takes precedence
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04059 Evaporative processes for the cooling of a fuel cell
• CPC Class Codes: H01M 8/04067 Heat exchange or temperature measuring elements, thermal insulation, e.g. heat pipes, heat pumps, fins
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/0618 Reforming processes, e.g. autothermal, partial oxidation or steam reforming
• CPC Class Codes: H01M 8/1011 : Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• CPC Class Codes: H01M 8/242 : comprising framed electrodes or intermediary frame-like gaskets H01M8/2425, H01M8/244 take precedence
• CPC Class Codes: H01M 8/2465 : Details of groupings of fuel cells
• CPC Class Codes: H01M 8/2483 : characterised by internal manifolds
• CPC Class Codes: Y02E 60/50 : Fuel cells

Abstract

The present invention relates to fuel cells and components used within a fuel cell. Heat transfer appendages are described that improve fuel cell thermal management. Each heat transfer appendage is arranged on an external portion of a bi-polar plate and permits conductive heat transfer between inner portions of the bi-polar plate and outer portions of the bi-polar plate proximate to the appendage. The heat transfer appendage may be used for heating or cooling inner portions of a fuel cell stack. Improved thermal management provided by cooling the heat transfer appendages also permits new channel field designs that distribute the reactant gases to a membrane electrode assembly. Flow buffers are described that improve delivery of reactant gases and removal of reaction products. Single plate bi-polar plates may also include staggered channel designs that reduce the thickness of the single plate.

Claims

13. A fuel cell for producing electrical energy, the fuel cell comprising:

a fuel cell plate stack including

a) a set of bi-polar plates, each bi-polar plate comprising

a first channel field disposed on a first face of the bi-polar plate and including a set of channels,

a second channel field disposed on a second face of the bi-polar plate and including a second set of channels, and

a flow buffer disposed on the first face and configured to reduce pressure variance of gaseous flow in the first channel field; and

b) a membrane electrode assembly disposed between two bi-polar plates, the membrane electrode assembly including a hydrogen catalyst, an oxygen catalyst and an ion conductive membrane that electrically isolates the hydrogen catalyst from the oxygen catalyst.

14. The fuel cell of claim 13 wherein the bi-polar plate includes a single plate and the first channel field and the second channel field are disposed on opposite faces of the single plate.

15. The fuel cell of claim 13 wherein the bi-polar plate includes:

a first plate that includes the first face; and

a second plate that includes the second face.

16. The fuel cell of claim 13 wherein the first channel field includes a set of channels configured to distribute oxygen to the oxygen catalyst.

17. The fuel cell of claim 16 wherein the flow buffer is configured with a volume that reduces a pressure difference of gases between two channels that it receives a gas from before outputting the gas to a channel that the flow buffer provides the gas to.

18. The fuel cell of claim 13 wherein a blockage in a channel included in the first channel field does not substantially compromise flow of a channel that the flow buffer outputs a gas to.

19. The fuel cell of claim 13 wherein the flow buffer reduces pressure variance for the first channel field.

20. The fuel cell of claim 13 wherein the flow buffer is configured to receive the gas from a third channel in the first set of channels.

21. The fuel cell of claim 20 wherein the flow buffer is configured with a volume that reduces a pressure difference of gases within the first and third channel before outputting the gaseous flow to the second channel.

22. The fuel cell of claim 20 wherein the first and third channel are both substantially straight and the third channel is substantially parallel to the first channel.

23. The fuel cell of claim 13 further comprising a second flow buffer configured to receive the gas from the second channel and output the gas to a third channel in a third set of channels in the first channel field.

24. The fuel cell of claim 13 wherein the fuel cell is configured to generate less than about 200 watts.

25. A bi-polar plate for use in a fuel cell, the bi-polar plate comprising:

a substrate having a first face and a second face;

a first channel field disposed on the first face; and

a second channel field disposed on the second face,

wherein a channel included in the first channel field has an overlapping channel depth that extends past a channel depth for a channel included in the second channel field.

26. The bi-polar plate of claim 25 wherein the bi-polar plate has a thickness between the first face and the second face that is less than 2x, where x is the approximate thickness of a channel used in the first channel field.

27. The bi-polar plate of claim 26 wherein the bi-polar plate has an overlapping channel depth greater than 5 mils.

28. The bi-polar plate of claim 26 wherein the bi-polar plate has an overlapping channel depth greater than 10 mils.

29. The bi-polar plate of claim 25 wherein channels in the first channel field have a channel depth greater than 10 mils.

30. The bi-polar plate of claim 29 wherein channels in the second channel field have a channel depth greater than 10 mils.

31. The bi-polar plate of claim 30 wherein the bi-polar plate has a thickness less than 20 mils.

32. The bi-polar plate of claim 25 wherein channels in the first channel field have a depth greater than 20 mils.

33. The bi-polar plate of claim 32 wherein channels in the second channel field have a depth greater than 20 mils.

34. The bi-polar plate of claim 33 wherein the bi-polar plate has a thickness less than 40 mils.

35. The bi-polar plate of claim 25 wherein a channel included in the first channel field has a channel bottom that extends past the mid-section of the bi-polar plate.

36. The bi-polar plate of claim 25 wherein channels in the first channel field are staggered such that they do not laterally intercept any channels in the second channel field.

37. A fuel cell for producing electrical energy, the fuel cell comprising:

a first bi-polar plate including a first channel field disposed on a first face of the plate;

a membrane electrode assembly including a hydrogen catalyst, an oxygen catalyst and an ion conductive membrane that electrically isolates the hydrogen catalyst from the oxygen catalyst;

a second bi-polar plate including a second channel field disposed on a face of the second bi-polar plate that opposes the first face of the first bi-polar plate when the first bi-polar plate and second bi-polar plate are assembled on opposite sides of the membrane electrode assembly;

a first landing on the first bi-polar plate that includes a surface area of the first bi-polar plate disposed between two channels in the first channel field; and

a second landing on the second bi-polar plate that includes a surface area of the second bi-polar plate disposed between two channels in the second channel field,

wherein the first landing at least partially overlaps the second landing when the first bi-polar plate and second bi-polar plate are assembled on opposite sides of the membrane electrode assembly.

38. The fuel cell of claim 37 wherein the membrane electrode assembly comprises a gas diffusion layer that contains the hydrogen catalyst.

39. The fuel cell of claim 38 wherein the gas diffusion layer comprises a compliant carbon layer.

40. The fuel cell of claim 37 wherein the overlap between the first landing and the second landing includes at least half the surface area between a channel on the first bi-polar plate and a nearest channel on the second bi-polar plate.

41. The fuel cell of claim 40 wherein the overlap between the first landing and the second landing includes at least ten percent of the surface area of the first bi-polar plate disposed between two adjacent channels in the first channel field.

42. The fuel cell of claim 37 wherein the first bi-polar plate includes a single plate and the first channel field and the second channel field are disposed on opposite faces of the single plate.

43. The fuel cell of claim 42 wherein a channel included in the first channel field has a channel bottom that extends past the mid-section of the first bi-polar plate.

44. The fuel cell of claim 42 wherein the overlap between the first landing and the second landing spans the thickness of the first bi-polar plate between the opposite faces of the first bi-polar plate.

45. A fuel cell for producing electrical energy, the fuel cell comprising:

a set of bi-polar plates, each bi-polar plate comprising a first channel field disposed on a first face of the bi-polar plate and including a set of channels, and comprising a second channel field disposed on a second face of the bi-polar plate and including a second set of channels;

a membrane electrode assembly disposed between two bi-polar plates, the membrane electrode assembly including a hydrogen catalyst, an oxygen catalyst and an ion conductive membrane that electrically isolates the hydrogen catalyst from the oxygen catalyst;

a top end plate; and

a bottom end plate that secures to the top end plate and applies pressure to the membrane electrode assembly when the top and bottom end plates are secured together,

wherein one of the top and bottom end plates are configured before assembly in the fuel cell such that assembly in the fuel cell reduces planar pressure variance in the membrane electrode assembly relative to a flat end plate used in assembly of the fuel cell in place of said one of the top and bottom end plates.

46. The fuel cell of claim 45 wherein the top end plate includes a convex curvature before assembly that reduces when the top end plate and bottom end plate are secured together.

47. The fuel cell of claim 45 wherein the convex curvature converts local forces from a bolt used to secure the top and bottom end plates to central planar compression of the membrane electrode assembly layers.

48. The fuel cell of claim 45 wherein both the top and bottom end plates are configured before assembly in the fuel cell such that assembly in the fuel cell reduces planar pressure variance in the membrane electrode assembly relative to a flat end plate used in assembly for both the top and bottom end plates.

49. The fuel cell of claim 45 wherein the top end-plate includes a channel field configured to distribute a gas to a membrane electrode assembly disposed adjacent to the top end-plate.

50. The fuel cell of claim 45 wherein each membrane electrode assembly employs an operating pressure from about 30 psi to about 400 psi.

51. A bi-polar plate for use in a fuel cell, the bi-polar plate comprising:

a substrate having a first face and a second face;

a first channel field disposed on the first face;

a second channel field disposed on the second face;

a manifold configured to deliver a gas to the first channel field or receive a gas from the first channel field; and

a manifold channel that opens to the manifold on the second face, traverses the substrate from the first face to the second face, and is configured to communicate gas between the manifold and the first channel field.

52. The bi-polar plate of claim 51 further comprising a second manifold channel that opens to the manifold on the second face, traverses the substrate from the first face to the second face, and is configured to provide the gas to the first channel field.

53. The bi-polar plate of claim 51 wherein the manifold channel opens to a flow buffer disposed in the first face that provides the gas to one or more channels in the first channel field.

54. The bi-polar plate of claim 51 wherein the first face comprises a gasket landing on the first face that peripherally surrounds the manifold on the first face.

55. The bi-polar plate of claim 54 wherein the gasket landing avoids intersection with the manifold channel on the first face.

56. The bi-polar plate of claim 51 wherein the second face comprises a second gasket landing on the second face that peripherally surrounds the manifold on the second face.

57. The bi-polar plate of claim 56 wherein the second gasket landing does not intersect the manifold channel on the second face.

58. A fuel cell for producing electrical energy, the fuel cell comprising:

a first bi-polar plate comprising i) a manifold configured to deliver a gas to a first channel field on a first face of the plate or receive a gas from the first channel field, and ii) a first gasket landing on the first face that peripherally surrounds the manifold on the first face;

a second bi-polar plate comprising a i) manifold that substantially aligns with the manifold of the first plate, and ii) a second gasket landing on a face of the second bi-polar plate that peripherally surrounds the second plate manifold, the second bi-polar plate face facing the first face of the first bi-polar plate when the first plate and second plate are disposed adjacent to each other; and

a membrane electrode assembly disposed between the first and second bi-polar plates, the membrane electrode assembly including a hydrogen catalyst, an oxygen catalyst and an ion conductive membrane that electrically isolates the hydrogen catalyst from the oxygen catalyst.

1. A bi-polar plate for use in a fuel cell, the bi-polar plate comprising:

a first channel field disposed on a first face of the bi-polar plate and including a set of channels;

a second channel field disposed on a second face of the bi-polar plate and including a second set of channels; and

a flow buffer configured to receive a gas from a first channel in the first set of channels and output the gas to a second channel in the first set of channels.

2. The bi-polar plate of claim 1 wherein the flow buffer reduces pressure variance for the first channel field.

3. The bi-polar plate of claim 1 wherein the flow buffer is configured to receive the gas from a third channel in the first set of channels.

4. The bi-polar plate of claim 3 wherein the flow buffer is configured with a volume that reduces a pressure difference of gases within the first and third channel before outputting the gaseous flow to the second channel.

5. The bi-polar plate of claim 3 wherein the first and third channel are both substantially straight and the third channel is substantially parallel to the first channel.

6. The bi-polar plate of claim 5 further comprising a second flow buffer configured to receive the gas from the second channel and output the gas to a third channel in a third set of channels in the first channel field.

7. The bi-polar plate of claim 1 the second flow buffer is configured to receive the gas from a fourth channel in the second set of channels.

8. The bi-polar plate of claim 7 wherein the second flow buffer is configured with a volume that reduces a pressure difference of gases within the second and fourth channels before outputting the gaseous flow to the third channel.

9. The bi-polar plate of claim 7 wherein the second and fourth channels are both substantially straight and the fourth channel is substantially parallel to the second channel.

10. The bi-polar plate of claim 1 wherein the gas comprises oxygen or hydrogen.

11. The bi-polar plate of claim 1 wherein the bi-polar plate includes a single plate and the first channel field and the second channel field are disposed on opposite faces of the single plate.

12. The bi-polar plate of claim 1 wherein the bi-polar plate includes:

a first plate that includes the first face; and

a second plate that includes the second face.

59. The fuel cell of claim 58 wherein one of the two bi-polar plates comprises a manifold channel that opens to the manifold on the second face, traverses the substrate from the first face to the second face, and is configured to provide the gas to the first channel field.

60. The fuel cell of claim 59 further comprising a second manifold channel that opens to the manifold on the second face, traverses the substrate from the first face to the second face, and is configured to provide the gas to the first channel field.

61. The fuel cell of claim 59 wherein the manifold channel opens to a flow buffer disposed in the first face that provides the gas to one or more channels in the first channel field.

62. The fuel cell of claim 59 wherein the first gasket landing does not intersect the manifold channel on the first face.

63. The fuel cell of claim 58 further comprising a gasket disposed between the two bi-polar plates and including a portion that rests between the first gasket landing and the second gasket landing.

62-1. The fuel cell of claim 59 wherein the other of the two bi-polar plates comprises a manifold channel that opens to the manifold on the second face, traverses the substrate from the first face to the second face, and is configured to provide the gas to the first channel field.