Fiber structures including catalysts and methods associated with the same

• US 7,229,944 B2
• Filed: 07/23/2004
• Issued: 06/12/2007
• Est. Priority Date: 07/23/2004
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Shao-Horn, Yang, Kurpiewski, John Paul, Horn, Quinn C.
• Primary Examiner(s): Lorengo; J. A.
• Assistant Examiner(s): Hailey; Patricia L.
• Application Number:
  US10/898,031
• Publication Number:
  US 20060019819A1
• Time in Patent Office: 1,054 Days
• Field of Search: 502/180, 502/182, 428/367, 423/447.1, 423/447.5
• US Class Current: 502/182
• CPC Class Codes: D01D 5/0038 the fibre formed by solvent evaporation, i.e. dry electro-spinning
• CPC Class Codes: D01F 1/02 Addition of substances to the spinning solution or to the melt addition of substances to viscose D01F2/08
• CPC Class Codes: D01F 9/14 by decomposition of organic filaments
• CPC Class Codes: D01F 9/20 from polyaddition, polycondensation or polymerisation products D01F9/145, D01F9/16, D01F9/18 take precedence
• CPC Class Codes: D01F 9/24 from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: H01M 4/663 containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
• CPC Class Codes: H01M 4/90 Selection of catalytic material
• CPC Class Codes: H01M 4/9083 on carbon or graphite
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y10T 428/2918 including free carbon or carbide or therewith [not as steel]

Abstract

Fiber structures that include a catalytic material are provided. The fiber structures (e.g., membranes) may be formed of interconnected carbon fibers. The catalytic material may be in the form of nanosize particles supported on the fibers. In one method of the invention, the structures are produced by electrospinning a polymeric material fiber structure that is subsequently converted to a carbon fiber structure in a heat treatment step which also causes the catalytic material particles to nucleate on the carbon fibers and grow to a desired size. The catalytic material may be uniformly distributed across the carbon fiber structure and the amount of catalytic material may be controlled. These factors may enhance catalytic performance and/or enable using less catalytic material for equivalent catalytic performance which can lead to cost savings, amongst other advantages. The fiber structures may be used in a variety of applications including electrodes in batteries and fuel cells.

Claims

1. A structure comprising:

a carbon fiber sheet-like structure having a thickness of less than 10 microns and including at least one carbon fiber having a length of greater than about 500 microns; and

a catalytic material supported on the carbon fiber sheet-like structure,

wherein carbon fiber of the structure has an avenge diameter of less than about 500 nanometers.

2. The structure of claim 1, comprising catalytic material particles supported on the carbon fiber structure.

3. The structure of claim 2, wherein the catalytic material particles have an average particle size of less than about 50 nanometers.

4. The structure of claim 2, wherein the catalytic material particles are formed on a surface of a carbon fiber of the structure.

5. The structure of claim 2, wherein the catalytic material particles are dispersed substantially throughout the carbon fiber structure.

6. The structure of claim 1, wherein the catalytic material particles have an average particle size of less than about 20 nanometers.

7. The structure of claim 1, wherein the catalytic material particles have an average particle size of less than about 1 nanometer.

8. The structure of claim 1, wherein the catalytic material concentration is substantially constant throughout the carbon fiber structure.

9. The structure of claim 1, wherein the catalytic material concentration is less than 0.2 mg catalytic material/cm² area of the carbon fiber structure.

10. The structure of claim 1, wherein carbon fiber of the structure has a conductivity of less than 0.1 Ohm-m.

11. The structure of claim 1, wherein the catalytic material is a metal.

12. The structure of claim 1, wherein the carbon fiber structure includes at least one carbon fiber having a length of greater than about 1 cm.

13. The structure of claim 1, wherein carbon fibers of the carbon fiber structure are solid.

14. The structure of claim 1, wherein a majority of the carbon fibers of the structure have a length of greater than about 500 microns.

15. A structure comprising;

a carbon fiber structure having a thickness of less than 10 microns and including at least one carbon fiber having a length of greater than about 500 microns; and

a plurality of catalytic material particles supported on the carbon fiber structure, the catalytic material particles having an average particle size of less than about 50 nanometers.

16. The structure of claim 15, wherein the catalytic material particles have an average particle size of less than about 20 nanometers.

17. The structure of claim 15, wherein the catalytic material particles have an average particle size of less than about 1 nanometer.

18. The structure of claim 15, wherein the catalytic material particles are formed on a surface of a carbon fiber of the structure.

19. The structure of claim 15, wherein the catalytic material particles are dispersed substantially throughout the carbon fiber structure.

20. The structure of claim 15, wherein the catalytic material particle concentration is substantially constant throughout the carbon fiber structure.

21. The structure of claim 15, wherein the catalytic material particle concentration is less than 0.2 mg catalytic material/cm² area of the carbon fiber structure.

22. The structure of claim 15, wherein carbon fiber of the structure has a conductivity of less than 0.1 Ohm-m.

23. The structure of claim 15, wherein the catalytic material particle is a metal.

24. The structure of claim 15, wherein the carbon fiber structure includes at least one carbon fiber having a length of greater than about 1 cm.

25. The structure of claim 15, wherein carbon fibers of the carbon fiber structure are solid.

26. The structure of claim 15, wherein a majority of the carbon fibers of the structure have a length of greater than about 500 microns.

27. The structure of claim 15, wherein carbon fiber of the structure has an average diameter of less than about 500 nanometers.

28. The structure of claim 15, wherein the carbon fiber structure is a membrane.

29. The structure of claim 15, wherein the carbon fiber structure is a sheet-like structure.

30. A structure comprising:

a carbon fiber structure including at least one carbon fiber having a length of greater than about 500 microns; and

a plurality of catalytic metal particles, supported on the carbon fiber structure and having an average particle size of less than about 50 nanometers.

31. The structure of claim 30, wherein the catalytic metal particles have an average particle size of less than about 20 nanometers.

32. The structure of claim 30, wherein the catalytic metal particles have an average particle size of less than about 1 nanometer.

33. The structure of claim 30, comprising catalytic metal particles supported on the carbon fiber structure.

34. The structure of claim 30, wherein the catalytic metal particles are formed on a surface of a carbon fiber of the structure.

35. The structure of claim 30, wherein the catalytic metal particles are dispersed substantially throughout the carbon fiber structure.

36. The structure of claim 30, wherein the catalytic metal particle concentration is substantially constant throughout the carbon fiber structure.

37. The structure of claim 30, wherein the catalytic metal particle concentration is less than 0.2 mg, catalytic material/cm² area of the carbon fiber structure.

38. The structure of claim 30, wherein carbon fiber of the structure has a conductivity of less than 0.1 Ohm-m.

39. The structure of claim 30, wherein the carbon fiber structure includes at least one carbon fiber having a length of greater than about 1 cm.

40. The structure of claim 30, wherein carbon fibers of the carbon fiber structure are solid.

41. The structure of claim 30, wherein a majority of the carbon fibers of the structure have a length of greater than about 500 microns.

42. The structure of claim 30, wherein carbon fiber of the structure has an average diameter of less than about 500 nanometers.

43. The structure of claim 30, wherein the carbon fiber structure has a thickness of less than 10 micron.

44. The structure of claim 30, wherein the carbon fiber structure is a membrane.

45. The structure of claim 30, wherein the carbon fiber structure is a sheet-like structure.