Organic fuel cell methods and apparatus

• US 7,445,859 B2
• Filed: 05/27/2004
• Issued: 11/04/2008
• Est. Priority Date: 10/12/1993
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology, University of Southern California
• Original Assignee: California Institute of Technology
• Inventors: Olah, George A., Prakash, G. K. Surya, Narayanan, Sekharipuram R., Frank, Harvey A., Surampudi, Subbarao, Halpert, Gerald, Vamos, Eugene
• Primary Examiner(s): Kalafut; Stephen J.
• Application Number:
  US10/857,587
• Publication Number:
  US 20040224214A1
• Time in Patent Office: 1,622 Days
• Field of Search: 429/15, 429/30, 429/34
• US Class Current: 429/494
• CPC Class Codes: H01M 2300/0082 Organic polymers
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/8807 Gas diffusion layers
• CPC Class Codes: H01M 4/8853 Electrodeposition
• CPC Class Codes: H01M 4/921 Alloys or mixtures with metallic elements
• CPC Class Codes: H01M 4/926 on carbon or graphite
• CPC Class Codes: H01M 8/0234 Carbonaceous material
• CPC Class Codes: H01M 8/0239 Organic resins; Organic polymers
• CPC Class Codes: H01M 8/0243 in the form of mixtures
• CPC Class Codes: H01M 8/04186 of liquid-charged or electrolyte-charged reactants
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1009 with one of the reactants being liquid, solid or liquid-charged H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1011 Direct alcohol fuel cells [DAFC], e.g. direct methanol fuel cells [DMFC]
• CPC Class Codes: H01M 8/1023 having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• CPC Class Codes: H01M 8/1039 halogenated, e.g. sulfonated polyvinylidene fluorides
• CPC Class Codes: H01M 8/1053 consisting of layers of polymers with at least one layer being ionically conductive
• CPC Class Codes: H01M 8/22 Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
• CPC Class Codes: H01M 8/2455 with liquid, solid or electrolyte-charged reactants
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A liquid organic, fuel cell is provided which employs a solid electrolyte membrane. An organic fuel, such as a methanol/water mixture, is circulated past an anode of a cell while oxygen or air is circulated past a cathode of the cell. The cell solid electrolyte membrane is preferably fabricated from Nafion™. Additionally, a method for improving the performance of carbon electrode structures for use in organic fuel cells is provided wherein a high surface-area carbon particle/Teflon™-binder structure is immersed within a Nafion™/methanol bath to impregnate the electrode with Nafion™. A method for fabricating an anode for use in a organic fuel cell is described wherein metal alloys are deposited onto the electrode in an electro-deposition solution containing perfluorooctanesulfonic acid. A fuel additive containing perfluorooctanesulfonic acid for use with fuel cells employing a sulfuric acid electrolyte is also disclosed. New organic fuels, namely, trimethoxymethane, dimethoxymethane, and trioxane are also described for use with either conventional or improved fuel cells.

Claims

1. A direct methanol feed fuel-cell, comprising:

a plurality of electrodes, including an anode and a cathode, and a proton conducting, solid polymer electrolyte between said anode and said cathode;

a fuel connection, operating to allow circulating an organic fuel which is free of an acid electrolyte into contact with the anode;

a second connection, allowing circulating air into contact with the cathode; and

wherein at least said anode includes a porous structure with an additive that promotes uniform wetting of pores within said porous structure by said organic fuel.

2. A fuel-cell as in claim 1, wherein said cathode is a gas diffusion electrode.

3. A fuel-cell as in claim 1, wherein said cathode includes a platinum containing catalyst associated therewith.

4. A fuel-cell as in claim 1, wherein said cathode is formed on a carbon backing paper, and said catalyst is formed on the carbon backing paper at a loading between 0.5 and 4 mg per centimeter squared.

5. A fuel-cell as in claim 1, wherein said anode, said cathode, and said electrolyte are formed into a composite layered structure.

6. A fuel cell as in claim 1, wherein said fuel is a methanol-containing fuel.

7. A fuel-cell as in claim 5, wherein said electrolyte membrane is a perfluorinated sulfonic acid polymer membrane.

8. A fuel-cell as in claim 5, wherein said cathode is a gas diffusion electrode.

9. A fuel-cell as in claim 5, wherein said organic fuel is a methanol containing fuel.

10. A method of forming a direct methanol feed fuel-cell, comprising:

obtaining a backing material for use in forming a porous anode structure;

forming an additive within the anode that promotes uniform wetting of the pores of the anode;

adding an electrocatalyst to the anode;

attaching the anode to a solid electrolyte membrane, and attaching said electrolyte membrane to a cathode; and

carrying out a chemical reaction by flowing organic fuel which is substantially free of acid electrolyte into contact with the anode.

11. A method as in claim 10, wherein said flowing comprises flowing methanol to the anode.

12. A fuel cell, comprising:

a plurality of electrodes, including an anode and a cathode;

a solid polymer electrolyte, coupled to and between said anode and cathode;

a first connection operating to allow circulating an organic fuel which is free of an acid electrolyte into contact with the anode;

a second connection, allowing bringing air into contact with the cathode; and

a gas separator operating to receive an output product from the fuel cell, and to separate gas within said output product from liquid within said output product, wherein said gas separator is formed of a microporous material; and

a recovery unit that recovers water from said output product after separating.

13. A fuel-cell as in claim 12, wherein said gas separators separates carbon dioxide from water.

14. A fuel-cell as in claim 12, wherein said cathode is a gas diffusion cathode with electrocatalyst particles.

15. A fuel-cell as in claim 14, wherein said cathode is treated with the material that aids in removal of water.

16. A fuel-cell as in claim 15, wherein said material is a hydrophobic material.

17. A fuel-cell as in claim 15, wherein said material is polytetrafluoroethylene.

18. A fuel cell as in claim 17, wherein the cathode contains 10-50% polytetrafluoroethylene by weight.

19. A fuel cell as in claim 15, wherein the cathode contains the material at a loading that is effective to create a three-phase boundary.

20. A fuel cell as in claim 12, wherein the organic fuel is a methanol containing fuel.

21. A method of operating a direct fed methanol fuel-cell, comprising:

circulating an organic fuel which is substantially free of an acid electrolyte to an anode of a direct methanol fuel cell that has a solid polymer electrolyte coupled to said anode, and a cathode coupled to said solid polymer electrolyte, and circulating air to said cathode to allow an electrochemical reaction which produces electricity and also produces an output product including water and gas; and

separating said gas from said water in said output product using a microporous material to carry out the separating; and

recycling the water after said separating.

22. A method as in claim 21, wherein said gas includes carbon dioxide.

23. A method as in claim 21, wherein said separating comprises using a material which allows gas to pass without passing liquid to separate said water from said gas.

24. A method as in claim 21, wherein said cathode is a gas diffusion cathode with electrocatalyst particles therein.

25. A method as in claim 24, wherein said cathode is treated with a hydrophobic material to aid in removing all of water.

26. A method as in claim 25, wherein the cathode contains said hydrophobic material in an amount which is effective to maintain a three-phase boundary.

27. A method as in claim 21, wherein said organic fuel is a methanol containing fuel.

28. A direct fed methanol fuel-cell, comprising:

a composite layered structure including an anode, a cathode, and a solid polymer electrolyte between said anode and cathode and adapted to operate with an organic fuel which is substantially free of acid electrolyte;

a gas separator, located adjacent said cathode, and operating to separate gas from a liquid.

29. A fuel-cell as in claim 28 further comprising:

means for circulating said organic fuel to said anode;

means for circulating gas to said cathode; and

wherein said gas separator operates to separate gas from liquid within an output product of the fuel-cell after an electrochemical reaction.

30. A fuel-cell as in claim 28, further comprising a fuel supply, which supplies said organic fuel to said anode to carry out an electrochemical reaction.

31. A fuel-cell as in claim 30, wherein said gas separator is a material which is permeable to gas but impermeable to liquid.

32. A fuel-cell as in claim 31, wherein said material is a microporous material.

33. A fuel-cell as in claim 28, wherein said cathode includes a treatment to reduce liquid permeation into said cathode.

34. A fuel cell as in claim 32, wherein the cathode contains a hydrophobic material at a loading that is effective to create a three-phase boundary.

35. A fuel cell as in claim 29, wherein the organic fuel is a methanol containing fuel.

36. A method, comprising:

carrying out an electrochemical reaction in a fuel-cell which involves introducing an organic fuel which is substantially free of acid electrolyte into an area of an anode of a direct methanol fuel cell that has a solid polymer electrolyte coupled to said anode, and a cathode coupled to said solid polymer electrolyte, to carry out a chemical reaction that produces electricity and releases water and gas; and

in an area of flow of said cathode, separating the water from the gas using a material that passes only one of water or gas, and reintroducing recovered water into an area of said anode.

37. A method as in claim 36, wherein said using a material comprises using a micro porous material.

38. A method as in claim 36, wherein said carrying out an electrochemical reaction comprises electrochemically processing a methanol containing fuel.

39. A method as in claim 38, further comprising treating the anode to allow improved wetting by the methanol containing fuel.

40. A method as in claim 38, further comprising treating at least one of said anode and/or cathode with an electrochemical catalyst material.

41. A method as in claim 40, wherein said electrochemical catalyst material is a platinum containing material.