Bipolar plates and end plates for fuel cells and methods for making the same

• US 20040191594A1
• Filed: 04/05/2004
• Published: 09/30/2004
• Est. Priority Date: 07/27/2001
• Status: Active Grant

• Current Assignee: Intelligent Energy Limited (Lb-shell Plc)
• Original Assignee: Eveready Battery Company Incorporated (Energizer Holdings, Inc.)
• Inventors: Kearl, Daniel A.
• Granted Patent: US 8,263,259 B2
• Time in Patent Office: Days
• US Class Current: 429/210
• CPC Class Codes: H01M 8/0204 Non-porous and characterised by the material
• CPC Class Codes: H01M 8/0206 Metals or alloys
• CPC Class Codes: H01M 8/0213 Gas-impermeable carbon-containing materials
• CPC Class Codes: H01M 8/0228 in the form of layered or coated products
• CPC Class Codes: H01M 8/026 characterised by grooves, e.g. their pitch or depth
• CPC Class Codes: H01M 8/0263 having meandering or serpentine paths
• CPC Class Codes: H01M 8/0267 having heating or cooling means, e.g. heaters or coolant flow channels
• CPC Class Codes: H01M 8/0269 Separators, collectors or interconnectors including a printed circuit board
• CPC Class Codes: H01M 8/0637 Direct internal reforming at the anode of the fuel cell
• CPC Class Codes: H01M 8/2483 characterised by internal manifolds
• 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

Bipolar plates and end plates for fuel cell stacks. The bipolar plates or end plates may include semi-conductive or conductive bodies, intricate features with close tolerances such as narrow flow channels and conduits with complex flow paths, integral resistive heating elements, internal catalytic reforming capability, integral heat exchanging structure, substantially flat and undistorted contact faces, integral sensors, and internal recuperative heat exchanging capacity.

Methods of making bipolar plates and end plates for fuel cell stacks. The methods involve a range of integrated processing techniques that enable a flexible approach to bipolar and end plate design. In addition, the ability to reliably produce features on a small scale allows for the potential miniaturization of bipolar plates and end plates and is therefore ideally suited to further the development of small scale portable fuel cell systems.

Claims

1-34. -34 (cancelled)

35. A method of making bipolar plate for a fuel cell stack, the method comprising the steps of:

providing a semi-conductive or conductive substrate having a first face and a second face;

etching a first flow channel from the first face; and

etching a second flow channel from the second face.

36. The method as defined in claim 35 wherein the substrate is selected from the group consisting of semiconductors, graphite, and metals.

37. The method as defined in claim 35 wherein the step of etching is performed using an etchant selected from the group consisting of wet anisotropic echants, wet isotropic elements, plasma anisotropic etchants, plasma isotropic etchants, and combinations thereof.

38. The method as defined in claim 35, the method further comprising the step of applying a mask to the first or second face of the substrate before the step of etching a flow channel from the masked face.

39. The method as defined in claim 38, the method further comprising the step of patterning the mask by photolithography before step of etching the flow channel from the first or second face.

40. The method as defined in claim 35, further comprising the step of coating the first channel with a reforming catalyst.

41. The method as defined in claim 40, wherein the step of coating the first flow channel with a reforming catalyst is performed by a coating method selected from the group consisting of sputter deposition, chemical vapor deposition, evaporation, electroplating, solution deposition, and combinations thereof.

42. The method as defined in claim 35, further comprising the step of creating a conduit wherein the conduit passes through the substrate.

43. The method as defined in claim 42 wherein the step of creating a conduit is performed by etching or a combination of etching and bonding.

44. The method as defined in claim 42 wherein the step of creating a conduit is performed by a method selected from the group consisting of drilling, abrasive machining, laser machining, and laser ablation.

45. The method as defined in claim 42, further comprising the step of coating the conduit with a reforming catalyst.

47. The method as defined in claim 45 wherein the step of creating the resistive element is performed by a combination of one or more methods selected from the group consisting of photolithography, wet etching, plasma etching, ion implantation, high temperature diffusion, boron concentration dependent etching, electrochemical etching, bonding, lift off, spin coating, dip coating, sputter deposition, evaporation, electroplating, solution deposition, and chemical vapor deposition.

48. The method as defined in claim 35, further comprising the step of micromachining a sensor from the bulk of the substrate or micromachining a sensor on the surface of the substrate.

49. The method as defined in claim 48 wherein the step of micromachining is performed by a combination of one or more methods selected from the group consisting of photolithography, wet etching, plasma etching, boron concentration dependent etching, electrochemical etching, bonding, lift off spin coating, dip coating, sputter deposition, evaporation, electroplating, solution deposition, and chemical vapor deposition.

46. The method as defined in clam 35, further comprising the step of creating a resistive element wherein the resistive element is located within the bulk of the bipolar plate or on the surface of the bipolar plate and is adapted to heat the bipolar plate.

50-54. -54 (cancelled)

55. A method of making an end plate for a fuel cell stack, the method comprising steps of:

providing a substantially planar semi-conductive or conductive substrate having a face; and

etching a flow channel from the face.

56. (cancelled)

57. A method of making a fuel cell stack comprising steps of:

providing a plurality of fuel cells;

providing a plurality of bipolar plates, each bipolar plate comprising

a semi-conductive body having a first face adapted to contact an anode of a first fuel cell and a second face adapted to contact a cathode of a second fuel cell, the first face including a first flow channel adapted to confine fuel fluids, and the second face including a second flow channel adapted to confine oxidizing fluids;

assembling the fuel cells and bipolar plates alternately to form a stack;

providing end plates; and

completing the stack with the end plates.

58. (cancelled)