Aqueous liquid feed organic fuel cell using solid polymer electrolyte membrane

• US 5,599,638 A
• Filed: 10/12/1993
• Issued: 02/04/1997
• Est. Priority Date: 10/12/1993
• Status: Expired due to Term

• Current Assignee: California Institute of Technology, University of Southern California
• Original Assignee: California Institute of Technology, University of Southern California
• Inventors: Vamos, Eugene, Olah, George A., Prakash, G. K. Surya, Narayanan, Sekharipuram R., Frank, Harvey A., Surampudi, Subbarao, Halpert, Gerald
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US08/135,007
• Time in Patent Office: 1,211 Days
• Field of Search: 427/115, 427/220, 427/221, 427/443.2, 429/15, 429/33, 429/42, 502/101
• 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. In a liquid feed direct fuel cell having an anode, a cathode, an electrolyte, means for circulating an organic fuel past the anode and means for flowing oxygen past the cathode, wherein the improvement comprises:

said electrolyte comprising a solid polymer hydrogen ion conductor membrane;

and wherein said organic fuel is free of an acid electrolyte.

2. The fuel cell of claim 1, wherein, said membrane is composed of a co-polymer of tetraflouroethylene and perflourocinylether sulfonic acid.

3. The fuel cell of claim 1, wherein said membrane is composed of a perfluorinated sulfonic acid polymer.

4. The fuel cell of claim 1, wherein said membrane is composed of a polyhydrocarbon sulfonic acid polymer.

5. The fuel cell of claim 1, wherein said membrane is composed of a composite of two or more hydrogen ion conductor membranes.

6. The fuel cell of claim 1, wherein said organic fuel is selected from a group consisting of methanol, formaldehyde, and formic acid.

7. The fuel cell of claim 1, wherein said organic fuel is selected from a group consisting of dimethoxymethane, trimethoxymethane and trioxane.

8. The fuel cell of claim 1, wherein said anode is an electrode impregnated with a hydrophilic proton conducting water-insoluble additive.

9. The fuel cell of claim 8, wherein said additive is a co-polymer of tetrafluoroethylene and perfluorovinylether sulfonic acid.

10. The fuel cell of claim 8, wherein said additive is montmorrolinite clay.

11. The fuel cell of claim 8, wherein said additive is an alkoxycellulose.

12. The fuel cell of claim 8, wherein said additive is a cyclodextrine.

13. The fuel cell of claim 8, wherein said additive is a mixture of zeolites.

14. The fuel cell of claim 8, wherein said additive is zirconium hydrogen phosphate.

15. A liquid feed fuel cell, comprising:

an anode;

a cathode;

a solid cation exchange polymer electrolyte membrane disposed between said anode and said cathode;

means for circulating a liquid organic fuel and water solution past said anode,

a liquid organic and water fuel solution, said solution being free of sulfuric acid; and

means for flowing oxygen past said cathode.

16. A liquid feed fuel cell, comprising:

an anode coated with an amount of hydrophilic proton conducting water-insoluble additive to provide ionic and electronic conductivity, wetting and gas evolving properties to said anode;

a cathode;

a cation exchange polymer electrolyte membrane disposed between said anode and said cathode;

means for flowing a liquid comprising organic fuel and water solution past said anode; and

means for flowing oxygen past said cathode.

17. The fuel cell of claim 16, wherein said membrane is a solid proton exchange membrane.

18. The fuel cell of claim 17, wherein said membrane is composed of a co-polymer of tetradluoroethylene and perfluorovinylether sulfonic acid.

19. The fuel cell of claim 17, wherein said membrane is composed of a perfluorinated sulfonic acid polymer.

20. The fuel cell of claim 17, wherein said membrane is composed of polyhydrocarbon sulfonic acid polymer.

21. The fuel cell of claim 17, wherein said membrane is composed of a composite of two or more proton exchange membranes.

22. The fuel cell of claim 16, wherein said organic fuel is selected from a group consisting of methanol, formaldehyde, and formic acid.

23. The fuel cell of claim 16, wherein said organic fuel is selected from a group consisting of dimethoxymethane, trimethoxymethane and trioxane.

24. The fuel cell of claim 16, wherein said additive is co-polymer of tetrafluoroethylene and perfluorovinylether sulfonic acid.

25. The fuel cell of claim 16, wherein said additive is montmorrolinite clay.

26. The fuel cell of claim 16, wherein said additive is an alkoxycellulose.

27. The fuel cell of claim 16, wherein said additive is a cyclodextrine.

28. The fuel cell of claim 16, wherein said additive is a mixture of zeolites.

29. The fuel cell of claim 16, wherein said additive is zirconium hydrogen phosphate.

30. A liquid feed fuel cell, comprising:

a housing having an anode chamber and a cathode chamber;

a co-polymer of tetrafluoroethylene and perfluorovinylether sulfonic acid polymer electrolyte membrane mounted within said housing and separating said anode and cathode chambers;

a cathode formed on a side surface of the membrane facing the cathode chamber;

an anode formed on an opposing side of the membrane facing the anode chamber, said anode being impregnated with co-polymer of tetrafluoroethylene and perfluorovinylether sulfonic acid;

means for circulating a liquid organic fuel and water solution past said anode;

means for flowing oxygen past said cathode;

means for withdrawing carbon dioxide from the anode chamber;

means for withdrawing unused fuel and water from the anode compartment; and

means for withdrawing unused oxygen and water from the cathode chamber.

31. An electrode comprising a metal alloy coated with an amount of hydrophilic proton conducting, water insoluble additive to provide ionic and electronic conductivity, wetting and gas evolving properties to the electrode.

32. A method for processing a carbon structure composed of carbon particles supported by a binder, said method comprising the steps of:

immersing the carbon structure within a bath containing a liquid perflourinated sulfonic acid polymer; and

removing and drying said carbon structure.

33. The method of claim 32, wherein said polymer is a 1% co-polymer of tetrafluoroethylene and perfluorovinylether sulfonic acid solution and said polymer is dispersed in methanol.

34. The method of claim 32, wherein said step of immersing said carbon structure in a bath containing a liquid polymer is performed for 5 to 10 minutes.

35. A structure processed according to the method of claim 32.

36. An electro-deposition bath for use in fabricating an electrode for use in a liquid feed fuel cell, comprising perfluorooctanesulfonic acid.

37. A method for fabricating an electrode for use in a fuel cell, said method comprising the steps of:

providing a bath containing a solution of metallic salts dissolved in sulfuric acid;

adding perfluorooctanesulfonic acid to said bath;

positioning a electrode having a carbon structure within said bath;

positioning an anode within said bath; and

applying a voltage between said anode and said electrode until a desired amount of metal in a range of 0.5-4.0 mg/cm² becomes deposited onto said electrode.

38. The method of claim 37, wherein said metal salts include hydrogen hexachloroplatinate and potassium pentachloroaquoruthenium.

39. The method of claim 37, wherein said anode is composed of platinum.

40. The method of claim 37, wherein said carbon electrode structure includes carbon combined with a polytetrafluoroethylene binder.

41. The method of claim 37, wherein said carbon electrode includes carbon bound by a 15%, by weight, polytetrafluoroethylene binder and applied on a carbon based fiber layer.

42. The method of claim 37, wherein said acid is provided with a concentration in the range of 0.01-0.05M.

43. The method of claim 37, including the further steps of extracting said electrode from said bath and washing said electrode in deionized water.

44. A method for fabricating an electrode having metal ions deposited thereon for use in a liquid organic fuel cell, said method comprising the steps of:

providing a bath comprising a solution of hydrogen hexachloroplatinate and potassium pentachloroaquoruthenium dissolved in sulfuric acid, wherein said hydrogen hexachloroplatinate and potassium pentachloroaquoruthenium has a concentration in the range 0.01-0.05M;

adding perfluorooctanesulfonic acid to said bath, with a concentration within the range of 0.1-1.0 grams /liter;

positioning a carbon electrode structure into said bath, wherein said carbon electrode structure has a mixture of carbon particles with a surface area of about 200 meters/gram a polytetrafluoroethylene binder, with the mixture applied to a fiber-based carbon paper;

positioning a platinum anode into said bath; and

applying a voltage between said anode and said electrode until a desired amount of platinum and ruthenium in the range of 0.5-4.0 mg/cm² become deposited onto said electrode.

45. An electrode fabricated according to the method of claim 44.

46. A liquid feed fuel cell, comprising:

an anode;

a cathode;

a liquid organic fuel, water, acid electrolyte and perfluorooctanesulfonic acid additive solution;

means for flowing said solution past said anode; and

means for flowing oxygen past said cathode.

47. A liquid feed fuel cell, comprising:

an anode;

a cathode;

an electrolyte;

a liquid organic fuel selected from a group consisting of trioxane, dimethoxymethane, and trimethoxymethane;

means for flowing said liquid organic fuel past said anode; and

means for flowing oxygen past said cathode.

48. The fuel cell of claim 47, wherein said fuel is dissolved in water to a concentration of between 0.1 and 2.0M.

49. A method for generating energy comprising the steps of:

providing a liquid-feed fuel cell; and

operating the liquid-feed fuel cell using an organic fuel selected from a group consisting of trioxane, dimethoxymethane and trimethoxymethane.