Organic vapor fuel cell

• US 20070092773A1
• Filed: 10/26/2005
• Published: 04/26/2007
• Est. Priority Date: 10/26/2005
• Status: Active Grant

• Current Assignee: Nanotek Instruments Group, LLC
• Original Assignee: Nanotek Instruments, Inc.
• Inventors: Zhamu, Aruna, Guo, Jiusheng, Jang, Bor
• Granted Patent: US 9,203,098 B2
• Time in Patent Office: Days
• US Class Current: 429/442
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 2250/30 Fuel cells in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 8/04007 related to heat exchange
• CPC Class Codes: H01M 8/04037 Electrical heating
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04186 of liquid-charged or electrolyte-charged reactants
• CPC Class Codes: H01M 8/04194 Concentration measuring cells
• CPC Class Codes: H01M 8/04197 Preventing means for fuel crossover
• CPC Class Codes: H01M 8/1004 characterised by membrane-electrode assemblies [MEA] H01M8/12 takes precedence
• CPC Class Codes: H01M 8/1007 with both reactants being gaseous or vaporised 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 8/1013 Other direct alcohol fuel cells [DAFC]
• CPC Class Codes: Y02B 90/10 Applications of fuel cells in buildings
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02T 90/40 Application of hydrogen technology to transportation, e.g. using fuel cells

Abstract

A fuel cell including primarily (a) a membrane electrode assembly, which comprises (i) a proton exchange membrane having a front face and a rear face, (ii) an anode being coupled to the front face, and (iii) a cathode being coupled to the rear face; (b) a fuel permeation-controlling member positioned in front of the anode; the member being substantially impermeable to an organic fuel or water at an ambient temperature or below, but being permeable at a temperature higher than an activation temperature; (c) heating means in control relation to the fuel permeation-controlling member to activate fuel permeation through the member on demand. The invented fuel cell is compact and lightweight, with significantly reduced fuel crossover and improved fuel utilization efficiency. The fuel cell is particularly useful for powering small vehicles and portable devices such as a notebook computer, a personal digital assistant, a mobile phone, and a digital camera.

Claims

1. An organic vapor fuel cell comprising:

(a) a membrane electrode assembly, comprising (i) a proton exchange membrane having a front face and a rear face, (ii) an anode being coupled to said front face with said front face and said anode defining an interface to accommodate an anode electro-catalyst therein, and (iii) a cathode being coupled to said rear face with said rear face and said cathode defining an interface to accommodate a cathode electro-catalyst therein;

(b) a fuel permeation-controlling member positioned in front of said anode, said member being substantially impermeable to an organic fuel and/or water at or below an ambient temperature, but being permeable to said organic fuel and/or water at a temperature higher than an activation temperature to deliver a permeated fuel fluid to said anode;

(c) heating means in heat-supplying relation to said fuel permeation-controlling member to activate fuel permeation through said member on demand; and

(d) fuel supply means to accommodate said organic fuel and water, separately or as a mixture, and provide said organic fuel and water as a feeding fuel to said permeation-controlling member.

2. The fuel cell as defined in claim 1, wherein said fuel supply means comprises (i) fuel flow channels in flow communication with said fuel permeation-controlling member and (ii) a liquid fuel source in supplying relation to said fuel flow channels.

3. The fuel cell according to claim 2, wherein said fuel flow channels comprise a porous fuel-permeating material in flow communication with said liquid fuel source.

4. The fuel cell according to claim 1, wherein said heating means comprises receiving heat produced by an electrochemical reaction of the fuel cell.

5. The fuel cell according to claim 1, wherein said heating means comprises receiving heat from joule heating by passing a current through a heating element implemented in the fuel cell.

6. The fuel cell according to claim 3, wherein said fuel-permeating material exhibits a capillary phenomenon, and is configured to receive said liquid fuel from said source by a capillary force.

7. The fuel cell according to claim 6, wherein the porous fuel-permeating material is selected from porous materials, cottons, papers, non-woven fabrics, or woven fabrics which produce a capillary action.

8. The fuel cell according to claim 7, wherein the porous material has a pore volume of 20 to 90% and a pore diameter of 0.01 to 150 μ

m.

9. The fuel cell according to claim 1, wherein said fuel permeation-controlling member is selected from the group consisting of a pervaporation membrane, vapor-permeating membrane, micro-filtration or ultra-filtration membrane, polymer containing an amorphous phase, ceramic-supported polymer membrane, composite membrane, and combinations thereof.

10. The fuel cell according to claim 1, wherein said organic fuel and water is supplied as a mixture at a first organic-to-water ratio while being accommodated in said fuel flow channels as a feeding fuel and said permeated fuel fluid is at a second organic-to-water ratio, which is different than said first ratio.

11. The fuel cell according to claim 10, wherein said organic fuel is methanol and said second ratio is approximately one-to-one on a molecular basis.

12. The fuel cell according to claim 1, further comprising (e) means for electrically interconnecting said anode and said cathode through an external load.

13. The fuel cell according to claim 1, wherein said fuel supply means comprises multiple separate chambers to accommodate said organic fuel and water.

14. The fuel cell according to claim 13, wherein said fuel permeation-controlling member comprises multiple fuel permeation zones.

15. The fuel cell according to claim 14, wherein a first chamber accommodates said organic fuel wetting a surface of a first fuel permeation zone and permeating therethrough when heated above an activation temperature, and a second chamber accommodates water wetting a surface of a second fuel permeation zone and permeating therethrough when heated above an activation temperature.

16. The fuel cell according to claim 1, further comprising a temperature sensor to monitor the temperature of said fuel permeation-controlling member.

17. The fuel cell according to claim 16, further comprising a temperature control device to regulate the temperature of said member.

18. The fuel cell according to claim 1, further comprising a tab being connected to or integral with said anode to serve as a negative terminal for transferring the electrons generated by the fuel cell.

19. The fuel cell according to claim 1, further comprising a supporting conductive layer being disposed between said anode and said fuel permeation-controlling member;

said conductive layer having a tab to serve as a negative terminal.

20. The fuel cell according to claim 19, wherein said supporting conductive layer is selected from the group consisting of a metallic screen, a porous metal sheet, a sheet of carbon foam, paper or felt, a perforated carbon plate, a sheet of carbon composite, and combinations thereof.

21. The fuel cell according to claim 1, wherein said organic fuel is selected from methanol, ethanol, propanol, isopropanol, trimethoxymethane, dimethoxymethane, dimethyl ether, trioxane, formaldehyde, formic acid, or a combination thereof.

22. The fuel cell according to claim 1, wherein said heating means comprises using a rechargeable battery to provide initial heating to begin a fuel cell operation.

23. The fuel cell according to claim 1, wherein said heating means comprises feeding a fraction of the current generated by said fuel cell to said heating element.

24. A plurality of electrically connected fuel cells, at least one of said fuel cells being a fuel cell as defined in claim 1.

25. The plurality of electrically connected fuel cells as defined in claim 24, wherein said fuel cells are connected in parallel.

26. The plurality of electrically connected fuel cells as defined in claim 24 wherein said fuel cells are connected in series.

27. A planar fuel cell system, comprising:

(a) a membrane electrode assembly, comprising one solid electrolyte sheet having a plurality of anodes disposed on only one major side of said solid electrolyte sheet and a plurality of corresponding cathodes disposed on only an opposing major side of said solid electrolyte sheet;

(b) a fuel permeation-controlling member positioned in front of said anode, said member being substantially impermeable to an organic fuel and/or water at or below an ambient temperature, but being permeable to said organic fuel and/or water at a temperature higher than an activation temperature to deliver a permeated fuel fluid to said anodes;

(c) heating means in heat-supplying relation to said fuel permeation-controlling member to activate fuel permeation through said member on demand;

(d) fuel supply means to deliver said organic fuel and water to said permeation-controlling member; and

(e) a plurality of current collectors each having an interconnect means;

wherein each of the plurality of anodes or each of the plurality of cathodes has one of said plurality of current collectors associated therewith, the interconnect means being arranged to provide electron transfer between anodes and cathodes.

28. The fuel cell system as described in claim 27, wherein the electron transfer between anodes and cathodes forms a series circuit.

29. The fuel cell system as described in claim 27, wherein said fuel supply means comprises a fuel chamber accommodating and supplying said organic fuel and water in a mixture form to said fuel permeation-controlling member.

30. The fuel cell system as described in claim 27, wherein said fuel supply means comprises a multiplicity of separate chambers, with at least two separate chambers accommodating said organic fuel and water on a separate basis, or with at least two separate chambers accommodating two organic fuel-water mixtures with different organic-to-water ratios.

31. The fuel cell system as described in claim 27, wherein said fuel permeation-controlling member comprises a multiplicity of fuel permeation membrane zones, at least two of said zones comprising different membrane materials or membranes of different thicknesses.

32. The fuel cell system as described in claim 31, wherein said fuel supply means comprises a multiplicity of separate chambers to accommodate and supply said organic fuel and water to said multiplicity of membrane zones, with at least two separate chambers accommodating said organic fuel and water on a separate basis, or with at least two separate chambers accommodating two organic fuel-water mixtures with different organic-to-water ratios.

33. A fuel cell comprising:

(a) a membrane electrode assembly, said membrane electrode assembly comprising (i) a proton exchange membrane having a front face and a rear face, (ii) an anode coupled to said front face, and (iii) a cathode coupled to said rear face;

(b) a vapor mixing and diffusion member positioned in front of said anode;

(c) a vapor-generating member positioned in front of said vapor mixing and diffusion member, said vapor-generating member comprising a plurality of membrane zones being substantially impermeable to an organic fuel and/or water in a liquid phase but being permeable to or capable of releasing said organic fuel or water in a vapor phase;

(d) fuel supply means comprising a plurality of fuel-feeding chambers corresponding to said plurality of membrane zones and feeding a fuel thereto, wherein the feeding fuel in first of said chambers differs in composition from the feeding fuel in a second of said chambers; and

(e) means for electrically interconnecting said anode and said cathode through an external load.

34. The fuel cell as defined in claim 33 wherein the feeding fuel in said first chamber comprises essentially water only and the feeding fuel in said second chamber comprises essentially said organic fuel only.

35. The fuel cell as defined in claim 33 wherein the feeding fuel in said first chamber comprises an organic fuel-water mixture with X% organic and (1-X%) water, and the feeding fuel in said second chamber comprises an organic fuel-water mixture with Y% organic and (1-Y%) water, where 1≦

X≦

100, 0≦

Y≦

100, and X≠

Y.

36. The fuel cell as defined in claim 33 wherein said vapor-generating member is selected from the group consisting of a pervaporation membrane, permselective membrane, an ionomeric membrane, a polymer gel, and combinations thereof.

37. The fuel cell as defined in claim 33 wherein said vapor-generating member is a sulfonated polymer, a porous ceramic membrane, a ceramic-supported polymer membrane, a ceramic-supported polymer gel, a composite membrane, or a combination thereof.

38. The fuel cell as defined in claim 33 wherein said vapor-generating member is electrically-conductive.

39. The fuel cell as defined in claim 33 further comprising an electrically-conductive, vapor-permeable member positioned between said vapor-generating member and said anode, said electrically-conductive, vapor-permeable member defining said vapor mixing and diffusion member.

40. The fuel cell as defined in claim 39 wherein said vapor-generating member is electrically-conductive and wherein said electrically-conductive, vapor-permeable member is in contact with each of said vapor-generating member and said anode.

41. The fuel cell as defined in claim 39 wherein said electrically-conductive, vapor-permeable member is selected from the group consisting of a metallic screen, porous metal sheet, carbon foam, carbon paper, carbon felt, carbon cloth, perforated metal, perforated carbon or graphite plate, perforated carbon or graphite composite, and combinations thereof.

42. A plurality of fuel cells connected in series, in parallel, or in both series and parallel, wherein at least one of said plurality of fuel cells is a fuel cell defined in claim 33.

43. A planar fuel cell system, comprising:

(a) a membrane electrode assembly, comprising one solid electrolyte sheet having a plurality of anodes disposed on only one major side of said solid electrolyte sheet and a plurality of corresponding cathodes disposed on only an opposing major side of said solid electrolyte sheet;

(b) a vapor mixing and diffusion member positioned in front of said anodes;

(c) a vapor-generating member positioned in front of said vapor mixing and diffusion member, said vapor-generating member comprising a plurality of membrane zones being substantially impermeable to an organic fuel and/or water in a liquid phase but being permeable to or capable of releasing said organic fuel or water in a vapor phase;

(d) fuel supply means comprising a plurality of fuel-feeding chambers corresponding to said plurality of membrane zones and feeding a fuel thereto, wherein the feeding fuel in a first of said chambers differs in composition from the feeding fuel in a second of said chambers; and

(e) a plurality of current collectors each having an interconnect means;

wherein each of the plurality of anodes or each of the plurality of cathodes has one of said plurality of current collectors associated therewith, the interconnect means being arranged to provide electron transfer between anodes and cathodes.

44. The planar fuel cell system as defined in claim 43 wherein one of the feeding chambers contains essentially water only and another feeding chamber contains essentially said organic fuel only.