Electrode for fuel cell, fuel cell system comprising the same, and method for preparing the same

• US 8,007,957 B2
• Filed: 11/28/2005
• Issued: 08/30/2011
• Est. Priority Date: 11/26/2004
• Status: Expired due to Fees

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Kim, Hee-Tak, Kim, Jan-Dee, Kweon, Ho-jin
• Primary Examiner(s): Gilliam, Barbara L.
• Assistant Examiner(s): Martin, Angela J
• Application Number:
  US11/289,134
• Publication Number:
  US 20060115712A1
• Time in Patent Office: 2,101 Days
• Field of Search: None
• US Class Current: 429/523
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/8807 Gas diffusion layers
• CPC Class Codes: H01M 4/8867 Vapour deposition
• CPC Class Codes: H01M 4/8871 Sputtering
• CPC Class Codes: H01M 4/8878 Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
• CPC Class Codes: H01M 4/92 Metals of platinum group H01M4/94 , H01M4/9058 take precedence
• CPC Class Codes: H01M 8/0234 Carbonaceous material
• CPC Class Codes: H01M 8/0245 in the form of layered or coated products
• 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

The electrode for a fuel cell of the present invention includes a carbonaceous electrode substrate, a microporous layer formed on the surface of the electrode substrate with the microporous layer including a carbonized polymer, and nano-carbon formed on the surface of the microporous layer with a catalyst layer coated on the surface of the nano-carbon. Alternatively, an electrode for a fuel cell includes a carbonaceous electrode substrate in which carbon particles are dispersed, a nano-carbon on the electrode substrate with a catalyst layer on the surface of the nano-carbon.

Claims

1. An electrode for a fuel cell system, comprising:

a carbonaceous electrode substrate;

a microporous layer on the surface of the electrode substrate, said microporous layer comprising a carbonized polymer; and

a nano-carbon and catalyst layer, comprising nano-carbon on the surface of the microporous layer with a catalyst layer on the surface of the nano-carbon.

2. The electrode of claim 1, wherein the electrode substrate is selected from the group consisting of carbon paper, carbon cloth, and carbon felt.

3. The electrode of claim 1, wherein the electrode substrate has a thickness of 10 μ

m to 1000 μ

m and the microporous layer has a thickness of 1 μ

m to 100 μ

m.

4. The electrode of claim 1, wherein the microporous layer comprises a material selected from the group consisting of carbon powder, graphite, fullerene (C60), carbon black, acetylene black, activated carbon, nano-carbon, and combinations thereof.

5. The electrode of claim 1, wherein the nano-carbon and catalyst layer has a thickness of 0.05 μ

m to 10 μ

m.

6. The electrode of claim 1, wherein the nano-carbon is selected from the group consisting of carbon nanotubes (CNT), carbon nanofiber, carbon nanowire, carbon nanohorns, carbon nanorings, and combinations thereof.

7. The electrode of claim 1, wherein the nano-carbon is oriented in a direction perpendicular to the surface of the microporous layer.

8. The electrode of claim 1, wherein the nano-carbon is directly on the surface of the microporous layer.

9. The electrode of claim 1, wherein the nano-carbon has a diameter of 1 to 500 nm.

10. The electrode of claim 1, wherein the content of the catalyst included in the catalyst layer is from 0.001 to 0.5 mg/cm².

11. The electrode of claim 10, wherein the content of the catalyst included in the catalyst layer is from 0.01 to 0.05 mg/cm².

12. The electrode of claim 1, wherein the specific surface area of the catalyst included in the catalyst layer per unit weight is 10 to 500 m²/g.

13. The electrode of claim 1, wherein the catalyst layer contains a metal selected from the group consisting of platinum, ruthenium, osmium, platinum-transition metal alloys, and combinations thereof.

14. The electrode of claim 1, wherein the catalyst layer is a metal catalyst on the surface of the nano-carbon.

15. The electrode of claim 14, wherein the metal catalyst is deposited using a method selected from the group consisting of sputtering, physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), thermal chemical vapor deposition, electron beam evaporation, vacuum thermal evaporation, laser ablation, and thermal evaporation.

16. The electrode of claim 1, wherein the polymer of the carbonized polymer is selected from the group consisting of polyvinylalcohol, polyacrylonitrile, phenol resin, polytetrafluoroethylene (PTFE), polyvinylidene fluoride, copolymers of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP), cellulose acetate, and combinations thereof.

17. A membrane-electrode assembly for a fuel cell, comprising a polymer electrolyte membrane, and

electrodes positioned on both sides of the polymer electrolyte membrane, where the electrodes comprise:

a carbonaceous electrode substrate;

a microporous layer on the surface of the electrode substrate, said microporous layer comprising a carbonized polymer; and

a nano-carbon and catalyst layer, comprising nano-carbon on a surface of the microporous layer with a catalyst layer on the surface of the nano-carbon.

18. A fuel cell system comprising:

at least one electricity generating unit comprising;

a membrane-electrode assembly comprising a polymer electrolyte membrane;

electrodes positioned on both sides of the polymer electrolyte membrane, wherein at least one electrode comprises a carbonaceous electrode substrate and a microporous layer on the surface of the electrode substrate, said microporous layer comprising a carbonized polymer, nano-carbon on the surface of the microporous layer, and a catalyst layer on the surface of the nano-carbon;

separators on both sides of the membrane-electrode assembly;

a fuel supplying unit for supplying hydrogen or fuel including hydrogen to the electricity generating unit; and

an oxidant supplying unit for supplying oxygen to the electricity generating unit.

19. The fuel cell system of claim 18, wherein the polymer electrolyte membrane is a proton-conducting polymer selected from the group consisting of perfluoro-based polymers, benzimidazole-based polymers, polyimide-based polymers, polyetherimide-based polymers, polyphenylene sulfide-based polymers, polysulfone-based polymers, polyethersulfone-based polymers, polyetherketone-based polymers, polyether-etherketone-based polymers, polyphenylquinoxaline-based polymers, and combinations thereof.

20. The fuel cell system of claim 19, wherein the polymer electrolyte membrane is selected from the group consisting of poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), co-polymers of tetrafluoroethylene and fluorovinylether containing sulfonic acid groups, defluorinated polyetherketone sulfides, aryl ketones, poly(2,2′

-(m-phenylene)-5,5′

-bibenzimidazole), poly(2,5-benzimidazole), and combinations thereof.

21. A method of preparing an electrode for a fuel cell, comprising:

forming a microporous layer on a surface of a carbonaceous electrode substrate;

heat-treating the carbonaceous electrode substrate with the microporous layer to carbonize a polymer in the microporous layer;

introducing a first catalyst for synthesizing nano-carbon on the surface of the microporous layer;

providing a reactive gas including a carbon source gas on the first catalyst to grow nano-carbon; and

coating a second catalyst on the nano-carbon to form a second catalyst layer.

22. The method of claim 21, wherein the electrode substrate is selected from the group consisting of carbon paper, carbon cloth, and carbon felt.

23. The method of claim 21, wherein the electrode substrate has a thickness of 10 μ

m to 1000 μ

m and the microporous layer has a thickness of 1 μ

m to 100 μ

m.

24. The method of claim 21, wherein the microporous layer comprises a material selected from the group consisting of carbon powder, graphite, fullerene (C60), carbon black, acetylene black, activated carbon, and nano-carbon, and combinations thereof.

25. The method of claim 21, wherein the first catalyst is selected from the group consisting of Fe, Ni, Co, Y, Pd, Pt, Au, Pd, Ga, Ti, V, Cr, Mn, Cu, Ta, W, Mo, Al, alloys of the metals, and metal-containing carbides, borides, oxides, nitrides, sulfides, sulfates, and nitrates.

26. The method of claim 21, wherein the carbon source gas is selected from the group consisting of hydrocarbon gas, carbon monoxide, carbon dioxide, and combinations thereof.

27. The method of claim 21, wherein the second catalyst layer has a thickness of 0.05 μ

m to 10 μ

m.

28. The method of claim 21, wherein the nano-carbon is selected from the group consisting of carbon nanotubes (CNT), carbon nanofiber, carbon nanowire, carbon nanohorns, carbon nanorings, and combinations thereof.

29. The method of claim 21, wherein the nano-carbon has a diameter of 1 to 500 nm.

30. The method of claim 21, wherein the content of the catalyst included in the second catalyst layer is from 0.001 to 0.5 mg/cm².

31. The method of claim 21, wherein the specific surface area of the catalyst included in the second catalyst layer per unit weight is in the range of 10 to 500 m²/g.

32. The method of claim 21, wherein the second catalyst is deposited using a method selected from the group consisting of sputtering, physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), thermal chemical vapor deposition, electron beam evaporation, vacuum thermal evaporation, laser ablation, thermal evaporation, and combinations thereof.

33. The method of claim 21, further comprising removing the first catalyst from the microporous catalyst layer.

34. The method of claim 33, wherein the first catalyst is removed by acid treatment.