Process For Application Of A Hydrophilic Coating To Fuel Cell Bipolar Plates

• US 20070031721A1
• Filed: 08/09/2006
• Published: 02/08/2007
• Est. Priority Date: 02/28/2005
• 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: Vyas, Gayatri, Winter, Gerhard, Trabold, Thomas, Datta, Reena
• Granted Patent: US 8,182,884 B2
• Time in Patent Office: Days
• US Class Current: 429/210
• CPC Class Codes: H01M 8/0206 Metals or alloys
• CPC Class Codes: H01M 8/0213 Gas-impermeable carbon-containing materials
• CPC Class Codes: H01M 8/0221 Organic resins; Organic polymers
• CPC Class Codes: H01M 8/0228 in the form of layered or coated products
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A process comprising: depositing a coating on a fuel cell bipolar plate using plasma assisted chemical vapor deposition.

Claims

1. A process comprising:

depositing a first coating over a fuel cell component comprising a substrate using a plasma assisted chemical vapor deposition using a precursor gas, the precursor gas comprising a compound comprising at least one Si—

O group, and at least one group including a saturated or unsaturated carbon chain.

2. A process as set forth in claim 1 further comprising pretreating the substrate, prior to depositing the first coating, to remove contaminants from the substrate.

3. A process as set forth in claim 1 further comprising pretreating the substrate, prior to depositing the first coating, to attach polar groups to the substrate.

4. A process as set forth in claim 3 wherein the polar groups comprises hydroxyl groups.

9. A process as set forth in claim 1 wherein the plasma assisted chemical deposition is conducted at a pressure ranging from 0 to 500 Pa.

10. A process as set forth in claim 1 wherein the plasma assisted chemical deposition is conducted at a pressure ranging from 10 to 100 Pa.

11. A process as set forth in claim 1 wherein the plasma assisted chemical deposition is conducted at a pressure ranging from 30-100 Pa.

12. A process as set forth in claim 1 wherein the plasma is generated by microwave energy.

13. A process as set forth in claim 12 wherein the microwave energy ranges from 50 W to 10 kW.

14. A process as set forth in claim 12 wherein the microwave energy ranges from 100 W to 1 kW.

15. A process as set forth in claim 12 wherein the microwave energy ranges from 200 W to 300 W.

16. A process as set forth in claim 15 wherein the volume of the reactor is about 110 liters.

17. A process as set forth in claim 1 further comprising a carrier gas.

18. A process as set forth in claim 17 wherein the carrier gas comprises at least one of air, nitrogen, argon, alkyamines, alkysilanes, ammonia, carbon dioxide, chloride, chlorine dioxide, chlorohydrocarbons, nitrous oxide, oxygen, ozone, water vapor or mixtures thereof.

19. A process as set forth in claim 17 wherein the precursor to carrier gas volume flow ratio ranges from 4-16 percent.

20. A process as set forth in claim 17 wherein the precursor to carrier gas volume flow ratio ranges from 4-12 percent.

21. A process as set forth in claim 17 wherein the precursor to carrier gas volume flow ratio ranges from 8-10 percent.

22. A process as set forth in claim 17 wherein the carrier gas comprises oxygen.

23. A process as set forth in claim 22 wherein the precursor to carrier gas volume flow ratio ranges from 4-16 percent.

24. A process as set forth in claim 22 wherein the precursor to carrier gas volume flow ratio ranges from 4-12 percent.

25. A process as set forth in claim 22 wherein the precursor to carrier gas volume flow ratio ranges from 8-10 percent.

26. A process as set forth in claim 22 wherein the carrier gas comprises O₂.

27. A process as set forth in claim 17 wherein the precursor gas flow rate ranges from 2-50 ml/minute and the carrier gas flow rate ranges from 20-625 ml/minute.

28. A process as set forth in claim 17 wherein the precursor gas flow rate ranges from 10-30 ml/minute and the carrier gas flow rate ranges from 100-375 ml/minute.

29. A process as set forth in claim 17 wherein the precursor gas flow rate ranges from 15-20 ml/minute and the carrier gas flow rate ranges from 150-250 ml/minute.

30. A process as set forth in claim 1 wherein the plasma is maintained at a steady state.

31. A process as set forth in claim 12 wherein the microwave power is pulsed using microsecond to nanosecond pulses.

32. A process as set forth in claim 1 further comprising post-treating the first coating to add polar groups to the compound.

33. A process as set forth in claim 1 further comprising post-treating the first coating comprising exposing the first coating to a plasma comprising oxygen.

34. A process as set forth in claim 33 wherein the exposing is conducted for a period up to 5 minutes.

35. A process as set forth in claim 33 wherein the exposing is conducted for a period ranging from 0.5 to 3 minutes.

36. A process as set forth in claim 32 wherein the polar group comprises a hydroxyl group, halide, carboxyl, ketonic or an aldehyde function group.

37. A process as set forth in claim 1 wherein the carbon chain has between 1 to 4 carbon atoms.

38. A process as set forth in claim 1 wherein the coating further comprises an electrically conductive material.

39. A product as set forth in claim 38 wherein the electrically conductive material comprises at least one of Au, Ag, Ru, Rh, Pd, Re, Os, Ir, Pt, rare earth metals, alloys thereof, polymeric carbon or graphite.

40. A product as set forth in claim 1 wherein the component comprises a bipolar plate.

41. A product as set forth in claim 1 wherein the substrate comprises a metal.

42. A product as set forth in claim 1 wherein the substrate comprises a polymeric composite material.

43. A product as set forth in claim 1 further comprising a second coating comprising an electrically conductive material and wherein the second coating overlies the substrate and the first coating overlies the second coating.

44. A product as set forth in claim 1 wherein the carbon chain is linear, branched or cyclic.

45. A process as set forth in claim 1 further comprising selectively depositing a mask over portions of the substrate leaving portions of the substrate unmasked and exposed prior to depositing a first coating over a fuel cell component.

46. A process as set forth in claim 45 wherein the mask is one of a hard mask, a washable mask, or a photoresist mask.

47. A process as set forth in claim 45 wherein the component is a bipolar plate having a plurality of lands and channels and wherein the mask is selectively deposited only over the lands.

48. A process as set forth in claim 1 wherein the component is a bipolar plate having a plurality of lands and channels and wherein the mask is selectively deposited only over portions of the bipolar plate prior to depositing the first coating over a fuel cell component, and thereafter removing the mask and any portion of the first coating overlying the mask.

49. A process as set forth in claim 1 wherein the component is a bipolar plate having a plurality of lands and channels and wherein the first coating is deposited over the lands and channels and selective portions of the first coating is thereafter removed.

50. A process as set forth in claim 1 wherein the component is a bipolar plate having a plurality of lands and channels and wherein the first coating is deposited over the lands and channels and the first coating over the lands is thereafter removed.

51. A process as set forth in claim 1 wherein the component is a bipolar plate having a plurality of lands and channels and wherein the first coating is deposited over the lands and channels, and further comprising selectively depositing a mask over portions of the first coating leaving portions of the first coating exposed, and thereafter removing the exposed portions of the first coating.

52. A process as set forth in claim 51 wherein the exposed portions are removed by etching.

53. A process as set forth in claim 1 wherein the mask is deposited only over the channels.

54. A process as set forth in claim 1 wherein the precursor gases comprising a material having the formula

55. A process as set forth in claim 32 wherein the polar groups comprise at least one of a hydroxyl, carboxyl or aldehyde functional group.

56. A process as set forth in claim 1 wherein the precursor comprises hexamethyl disoloxane.

74. A process as set forth in claim 54 wherein at least one of R₁, R₂, R₃, R₄, R₅, or R₆, is a carbon chain having at least one carbon atom.

5. A process comprising pretreating the substrate, prior to depositing the first coating, comprising exposing the substrate to a plasma comprising oxygen.

6. A process comprising pretreating the substrate, prior to depositing the first coating, comprising exposing the substrate to a microwave generated plasma comprising oxygen.

7. A process as set forth in claim 6 wherein the exposure is for a period of up to 5 minutes.

8. A process as set forth in claim 6 wherein the exposure is for a period of 0.5 to 3 minutes.

57. A process comprising:

depositing a first coating over a fuel cell component comprising a substrate using a plasma assisted chemical vapor deposition using a precursor gas, the precursor gas comprising a first compound comprising at least one of a silxoane or silanol.

58. A process as set forth in claim 57 wherein the plasma assisted chemical vapor deposition further comprising a second gas comprising oxygen.

59. A process as set forth in claim 58 wherein the coating comprises a second compound and further comprising treating the first coating to add polar groups to the second compound.

60. A process comprising:

depositing a first coating over a fuel cell component comprising a substrate using a plasma assisted chemical vapor deposition comprising flowing a silane gas, a gas comprising a compound comprising a carbon chain and a gas comprising oxygen.

61. A process comprising:

depositing a first coating over a fuel cell component comprising a substrate using a plasma assisted chemical vapor deposition comprising flowing a gas comprising a first compound comprising silicon, a second gas comprising a second compound comprising a carbon chain and a third gas comprising compound comprising oxygen.

62. A process comprising:

depositing a coating over a fuel cell component using plasma assisted chemical vapor deposition flowing a precursor gas into a plasma reaction chamber and flowing a carrier gas into the plasma reaction chamber, wherein the molar flow rate ratio of the precursor to carrier gas ranges from about 4 to about 16 percent.

63. A process as set forth in claim 62 wherein the molar flow rate ratio of the precursor to carrier gas ranges from about 4 to about 12 percent.

64. A process as set forth in claim 62 wherein the molar flow rate ratio of the precursor to carrier gas ranges from about 8 to about 10 percent.

65. A process as set forth in claim 62 wherein the precursor gas comprises hexamethyl disiloxane and the carrier gas comprises oxygen.

66. A process as set forth in claim 62 further comprising post-treating the coating to add polar groups.

67. A process as set forth in claim 62 further comprising post-treating the coating comprising exposing the coating to a plasma comprising oxygen ions.

68. A process as set forth in claim 62 further comprising pre-treating the fuel cell component prior to the depositing comprising attaching polar groups to the fuel cell component.

69. A process comprising:

depositing a coating on a fuel cell bipolar plate using plasma assisted chemical vapor deposition.

71. A process as set forth in claim 69 wherein the using plasma assisted chemical vapor deposition comprises flowing a precursor gas into a plasma reaction chamber and wherein the precursor gas comprises at least one of carbon or silicon.

72. A process as set forth in claim 69 wherein the using plasma assisted chemical vapor deposition comprises flowing a precursor gas into a plasma reaction chamber and wherein the precursor gas comprises carbon and silicon.

73. A process as set forth in claim 72 further comprising flowing a carrier gas into the plasma reaction chamber, wherein the carrier gas comprises oxygen.

70. A process as set forth further comprising masking a portion of the bipolar plate prior to depositing.