USRE37656EExpiredUtilityPatentIndex 96

Electrode apparatus containing an integral composite membrane

Assignee: GORE & ASSPriority: Mar 15, 1995Filed: Jun 3, 1999Granted: Apr 16, 2002

Est. expiryMar 15, 2015(expired)· nominal 20-yr term from priority

Inventors:BAHAR BAMDAD MALLOUK ROBERT S HOBSON ALEX R KOLDE JEFFREY A

B01D 69/141H01M 8/1023H01M 8/106C08J 2327/18H01M 8/1062C08J 5/225H01M 8/1039C25B 13/08H01M 8/1044B01D 67/0088Y02E60/50

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Claims

Abstract

A composite membrane is provided which includes a base material and an ion exchange resin. The base material has a microstructure characterized by nodes interconnected by fibrils, or a microstructure characterized by fibrils with no nodes present. The ion exchange resin substantially impregnates the membrane such that the membrane is essentially air impermeable.

Claims

exact text as granted — not AI-modified

Having described the invention, what is claimed is:

1. An electrode apparatus adapted for use in an electrochemical system, the electrode apparatus comprising composite membrane comprising:
(a) an at least one expanded polytetrafluoroethylene membrane having a porous microstructure of polymeric fibrils and having a thickness of 80 microns or less; and
(b) an at least one ion exchange material impregnated throughout the porous microstructure of the expanded polytetrafluoroethylene membrane so as to render an interior volume of the expanded polytetrafluoroethylene membrane substantially occlusive, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10,000 seconds, wherein the ion exchange material substantially impregnates the membrane so as to render an interior volume of the membrane substantially occlusive .

2. The electrode apparatus of claim 1 , wherein the expanded polytetrafluoroethylene membrane is expanded polytetrafluoroethylene having has a microstructure defined by nodes interconnected by fibrils.

3. The electrode apparatus of claim 1 , wherein the total thickness of the expanded polytetrafluoroethylene membrane is less than 13 μm microns .

4. The electrode apparatus of claim 1 , wherein the electrochemical system is a fuel cell.

5. The electrode apparatus of claim 1 , wherein the electrochemical system is an electrodialysis system.

6. The electrode apparatus of claim 1 , wherein the thickness of the expanded polytetrafluoroethylene membrane is 60 microns or less.

7. The electrode apparatus of claim 1 , wherein the thickness of the expanded polytetrafluoroethylene membrane is 40 microns or less.

8. The electrode apparatus of claim 1 , wherein the thickness of the expanded polytetrafluoroethylene membrane is 20 microns or less.

9. The electrode apparatus of claim 1 , wherein the thickness of the expanded polytetrafluoroethylene membrane is at least 1 . 5 microns.

10. The electrode apparatus of claim 1 , wherein the at least one ion exchange material is complimented by powder, non- ionic polymer, or a combination thereof.

11. The electrode apparatus of claim 10 , wherein the at least one ion exchange material is complimented by silica.

12. The electrode apparatus of claim 10 , wherein the at least one ion exchange material is complimented by platinum.

13. An electrode apparatus adapted for use in an electrochemical system, the electrode apparatus comprising a composite membrane consisting essentially of:
( a ) at least one expanded polytetrafluoroethylene membrane having a porous microstructure of polymeric fibrils and having a thickness of 80 microns or less; and
( b ) at least one ion exchange material impregnated throughout the porous microstructure of the expanded polytetrafluoroethylene membrane so as to render an interior volume of the expanded polytetrafluoroethylene membrane substantially occlusive, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10 , 000 seconds.

14. The electrode apparatus of claim 13 , wherein the expanded polytetrafluoroethylene membrane has a microstructure defined by nodes interconnected by fibrils.

15. The electrode apparatus of claim 13 , wherein the thickness of the expanded polytetrafluoroethylene membrane is less than 25 microns.

16. The electrode apparatus of claim 13 , wherein the electrochemical system is a fuel cell.

17. The electrode apparatus of claim 13 , wherein the electrochemical system is an electrodialysis system.

18. The electrode apparatus of claim 13 , wherein the at least one ion exchange material is complimented by silica.

19. The electrode apparatus of claim 13 , wherein the at least one ion exchange material is complimented by platinum.

20. An electrode apparatus comprising:
( a ) at least one porous polymeric membrane having a microstructure of micropores with a porosity of greater than 35 % and a thickness of at most 25 microns; and
( b ) at least one perfluoro ion exchange material impregnated within the micropores of the polymeric membrane so as to render them substantially occlusive.

21. The electrode apparatus according to claim 20 , wherein the thickness is at most 20 microns.

22. The electrode apparatus according to claim 20 , wherein the porosity is greater than 70 % .

23. An electrode apparatus according to claim 20 , wherein the perfluoro ion exchange material is locked inside the membrane which prevents the material from migrating to the surface during drying of the impregnated perfluoro ion exchange material.

24. An electrode apparatus according to claim 20 , wherein the thickness is at most 6 microns.

25. An electrode apparatus comprising:
an ultra - thin composite membrane comprising:
( a ) at least oneporous polymeric membrane having a microstructure of micropores with a porosity of greater than 35 % and a thickness of at most 25 microns; and
( b ) at least one perfluoro ion exchange material fully impregnated within the micropores of the polymeric membrane so as to render them fully occlusive, wherein the composite membrane is air impermeable with a Gurley number of greater than 10 , 000 seconds.

26. An electrode apparatus according to claim 25 , wherein the thickness is at most 20 microns.

27. An electrode apparatus according to claim 25 , wherein the thickness is at most 6 microns.

28. An electrode apparatus according to claim 25 , wherein the porosity is greater than 70 % .

29. An electrode apparatus according to claim 25 , wherein the composite membrane is heated at 60 ° C. to 200 ° C.

30. A fuel cell comprising a composite membrane located between an anode and a cathode, the composite membrane comprising:
( a ) at least one porous polymeric membrane having a microstructure of micropores with a porosity of greater than 35 % and a thickness of at most 25 microns; and
( b ) at least one perfluoro ion exchange material impregnated within the micropores of the polymeric membrane so as to render them substantially occlusive.

31. A fuel cell according to claim 30 , wherein the porosity is greater than 70 % .

32. A fuel cell according to claim 30 , wherein the composite membrane is heated at 60 ° C. to 200 ° C.

33. A fuel cell according to claim 30 , wherein the composite membrane is heated so as to lock the perfluoro ion exchange material inside the membrane.

34. A fuel cell according to claim 30 , wherein the thickness is at most 20 microns.

35. A fuel cell according to claim 30 , wherein the thickness is at most 13 microns.

36. A fuel cell comprising a composite membrane located between an anode and a cathode, the composite membrane comprising:
( a ) at least oneporous polymeric membrane having a microstructure of micropores with a porosity of greater than 35 % and a thickness of at most 25 microns; and
( b ) at least one perfluoro ion exchange material fully impregnated within the micropores of the polymeric membrane, wherein the composite membrane is air impermeable with a Gurley number of greater than 10 , 000 seconds.

37. A fuel cell according to claim 36 , wherein the porosity is greater than 70 % .

38. A fuel cell according to claim 36 , wherein the ion exchange material is locked within the composite membrane.

39. A fuel cell according to claim 37 , wherein the ion exchange material is locked within the composite membrane.

40. A fuel cell according to claim 36 , wherein the thickness is at most 20 microns.

41. An electrode apparatus comprising:
( a ) at least one expanded polytetrafluoroethylene membrane having a porous microstructure of polymeric fibrils and a total thickness of less than 20 microns; and
( b ) at least one ion exchange material impregnated throughout the membrane, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10 , 000 seconds, wherein the ion exchange material substantially impregnates the membrane to render an interior volume of the membrane substantially occlusive.

42. A electrode apparatus according to claim 41 , wherein the porosity of the expanded polytetrafluoroethylene membrane is greater than 70 % .

43. A electrode apparatus according to claim 41 , wherein the perfluoro ion exchange material is locked inside the membrane.

44. A electrode apparatus according to claim 41 , wherein the impregnated membrane is heated at 120 ° C. to 160 ° C.

45. A electrode apparatus according to claim 41 , wherein the total thickness is at most 13 microns.

46. A fuel cell comprising a composite membrane located between an anode and a cathode, the composite membrane comprising:
( a ) at least one expanded polytetrafluoroethylene membrane having a porous microstructure of polymeric fibrils and a total thickness of less than 20 microns; and
( b ) at least one ion exchange material impregnated throughout the membrane, the impregnated expanded polytetrafluoroethylene membrane having a Gurley number of greater than 10 , 000 seconds, wherein the ion exchange material substantially impregnates the membrane to render an interior volume of the membrane substantially occlusive.

47. A fuel cell according to claim 46 , wherein the porosity of the expanded polytetrafluoroethylene membrane is greater than 70 % .

48. A fuel cell according to claim 46 , wherein the composite membrane is heated at 60 ° C. to 200 ° C.

49. A fuel cell according to claim 46 , wherein the composite membrane is heated at 120 ° C. to 160 ° C.

50. A fuel cell according to claim 46 , wherein the total thickness is at most 13 microns.

51. An electrode apparatus comprising a laminate of composite membranes consisting essentially of at least two composite membranes laminated to each other, wherein the at least two composite membranes each consist essentially of:
( a ) at least one expanded polytetrafluoroethylene membrane having a porous microstructure of polymeric fibrils and having a thickness of 80 microns or less; and
( b ) at least one ion exchange material impregnated throughout the porous microstructure of the membrane so as to render an interior volume of the expanded polytetrafluoroethylene membrane substantially occlusive, the impregnated membrane having a Gurley number of greater than 10 , 000 seconds.

52. An electrode apparatus according to claim 51 , wherein the thickness of the laminate is 40 microns or less.

53. An electrode apparatus according to claim 51 , wherein at least two of the impregnated membranes are impregnated with ion exchange material before lamination to form the laminate.

54. An electrode apparatus according to claim 51 , wherein the laminate is prepared by the combination of steps comprising:
( i ) impregnation of at least one first unimpregnated expanded polytetrafluoroethylene membrane with ion exchange material to form a first impregnated membrane,
( ii ) lamination of the first impregnated membrane with a second unimpregnated expanded polytetrafluoroethylene membrane, and
( iii ) impregnation of the second unimpregnated expanded polytetrafluoroethylene to form a second impregnated membrane which is laminated to the first impregnated membrane.

55. An electrode apparatus according to claim 51 , wherein lamination is carried out by heat.

56. An electrode apparatus according to claim 51 , wherein each of the impregnated polytetrafluoroethylene membranes have been heated to a temperature of at least 60 ° C. and each of the impregnated membranes have an ionic conductance of at least 22 . 7 mhos/cm 2 ; wherein the thickness of each of the impregnated membranes is 20 microns or less; wherein the ion exchange material is perfluorinated sulfonic acid resin; wherein each of the impregnated membranes are prepared by multiple impregnations of two sides of the expanded polytetrafluoroethylene membrane with ion exchange material.

57. An electrode apparatus according to claim 56 , wherein the thickness of the laminate is 40 microns or less.

58. A fuel cell comprising a laminate membrane consisting essentially of at least two composite membranes laminated to each other, wherein each of the composite membranes are prepared by a combination of steps consisting essentially of:

providing at least one microporous expanded polytetrafluoroethylene membrane having a thickness of 80 microns or less;

impregnating the microporous membrane with ion exchange material so the impregnated membrane has a Gurley number of at least 10 , 000 seconds;

heating the impregnated membrane to between 60 ° C. and 200 ° C.

59. A fuel cell according to claim 58 , wherein the thickness of the laminate membrane is 60 microns or less.

60. A fuel cell according to claim 58 , wherein the thickness of the laminate membrane is 40 microns or less.

61. A fuel cell according to claim 58 , wherein the thickness of the laminate membrane is 20 microns or less.

62. A fuel cell according to claim 58 , wherein the laminate membrane has an ionic conductance of at least 8 . 5 mhos/cm 2 .

63. A fuel cell according to claim 58 , wherein the laminate membrane has an ionic conductance of at least 22 . 7 mhos/cm 2 .

64. A method for preparing an electrode apparatus comprising the step of:

locating at least one ion exchange membrane between an anode and a cathode, wherein the ion exchange membrane comprises

( a ) at least one porous polymeric membrane having a microstructure of micropores with a porosity of greater than 35 % and a thickness of at most 25 microns; and
( b ) at least one perfluoro ion exchange material impregnated within the micropores of the polymeric membrane so as to render them substantially occlusive.

65. A method according to claim 64 , wherein the thickness is at most 20 microns.

66. A method according to claim 64 , wherein the thickness is at most 13 microns.

67. A method according to claim 64 , wherein the thickness is at most 6 microns.

68. A method according to claim 64 , wherein the electrode apparatus is a fuel cell.

69. A method according to claim 64 , wherein the porosity is greater than 70 % .

70. A method according to claim 69 , wherein the thickness is at most 6 microns.

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