대표
청구항
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What is claimed is: 1. A direct oxidation fuel cell, comprising: (A) a membrane, sufficiently thin to allowe a rate of internal supply of water from a cathode side to an anode side of the fuel cell to be enhanced, said membrane intimately interfacing with a catalyst layer along each of said membrane's major surfaces, having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said fuel cell; (C) a fuel chamber in fluid communication with said anode aspect, said fuel chamber having no liquid outlet, and being filled or fed with fuel an...
What is claimed is: 1. A direct oxidation fuel cell, comprising: (A) a membrane, sufficiently thin to allowe a rate of internal supply of water from a cathode side to an anode side of the fuel cell to be enhanced, said membrane intimately interfacing with a catalyst layer along each of said membrane's major surfaces, having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said fuel cell; (C) a fuel chamber in fluid communication with said anode aspect, said fuel chamber having no liquid outlet, and being filled or fed with fuel and said fuel chamber having a passive mass transport barrier that is configured to defines a rate of fuel delivery of about 10-50% higher than a rate of anodic consumption of methanol in the fuel cell; and (D) effective water supply from cathode to anode within said fuel cell, so that water management in said fuel cell is achieved without water transport from cathode to anode external to the active volume of the fuel cell. 2. The direct oxidation fuel cell as defined in claim 1 wherein the fuel is neat methanol having substantially zero water content. 3. The direct oxidation fuel cell as defined in claim 1 wherein said passive mass transport barrier is disposed in a plane that is generally parallel to that of the anode aspect. 4. The direct oxidation fuel cell as defined in claim 1 wherein said rate of fuel delivery by said passive mass transport barrier is a defined rate calculated with reference to design cell current. 5. The direct oxidation fuel cell as defined in claim 4 wherein said de-fined rate is calculated such that fuel delivery is controlled to achieve a limiting current density on the order of one of the following: about 100-200 mA/cm2 at cell operation temperature of about 30-40 deg.C.; on the order of about 150-300 mA/cm2 at cell operation temperature of about 40-60 deg.C. and about 200-400 mA/cm2 at cell operation temperature of 60-80 deg.C. 6. The direct oxidation fuel cell as defined in claim 4 wherein said rate of fuel delivery by said passive mass transport barrier corresponds to a rate of fuel consumption by the fuel cell, as gauged by the design cell current at a design point of operation, multiplied by a factor of between about 1.1 and 1.5. 7. The direct oxidation fuel cell as defined in claim 1 wherein said passive mass transport barrier is a pervaporation fuel delivery membrane that effects a phase change such that liquid fuel on transporting through said fuel delivery membrane is converted to a vaporous fuel. 8. The direct oxidation fuel cell as defined in claim 7 wherein said fuel delivery membrane effects a vapor delivery rate, as gauged by a design cell current at a design point of operation multiplied by a factor of between about 1.1 and 1.5. 9. The direct oxidation fuel cell as defined in claim 7 wherein a vapor chamber is defined in a gap between said fuel delivery membrane and said anode aspect of the membrane, said vapor chamber maintaining a significant fraction of it's volume free of liquid. 10. The direct oxidation fuel cell as defined in claim 1 wherein said passive mass transport barrier is a microporous structure having perforations that deliver and direct liquid fuel to the anode aspect of the membrane at a defined rate. 11. The direct oxidation fuel cell as defined in claim 10, wherein said microporous structure is disposed in a plane that is generally parallel to that of the anode aspect. 12. The direct oxidation fuel cell as defined in claim 1 wherein said passive mass transport barrier is a solid porous plug having a pore network that provides for a capillary-force-controlled flow of fuel at the defined rate. 13. The direct oxidation fuel cell as defined in claim 1 wherein said fuel is up to 100% methanol. 14. The direct oxidation fuel cell as defined in claim 1 further comprising at least one gas exit port defined in said anode chamber such that gaseous anode products are released directly to the ambient environment, and said gas exit port being located in close proximity to said anode aspect of the catalyzed membrane. 15. The direct oxidation fuel cell as defined in claim 14 wherein said gas exit port is a vent in a carbon dioxide router device. 16. The direct oxidation fuel cell as defined in claim 1 wherein water generated in a reaction at the cathode aspect of the membrane is supplied back from a cathode to anode side of said fuel cell at rate sufficient to provide an amount of water that is required for substantially complete anodic oxidation of fuel at the highest cell current capable. 17. The direct oxidation fuel cell as defined in claim 16 further comprising a wet-proofed cathode backing disposed in the cathode chamber, and a hydrophobic microporous layer, being substantially comprised of expanded PTFE, disposed generally between the cathode backing and the cathode aspect of the membrane, to enhance the rate of supply of water back from the cathode side of the fuel cell to the anode side of the fuel cell. 18. The direct oxidation fuel cell as defined in claim 17 wherein said microporous layer is robust bonded to the cathode aspect by hot-pressing under controlled humidity conditions. 19. The direct oxidation fuel cell as defined in claim 17 wherein said microporous layer is secured to said cathode aspect of the membrane by compression across the cell thickness dimension of over 50 PSI, to establish substantially sustained adherence. 20. The direct oxidation fuel cell as defined in claim 17 wherein said microporous layer that is comprised substantially of expanded PTFE also includes embedded carbon microparticles. 21. The direct oxidation fuel cell as defined in claim 17 wherein said hydrophobic microporous layer is deposited directly onto the wet-proofed cathode backing. 22. The direct oxidation fuel cell as defined in claim 1 wherein said catalyzed membrane is sufficiently thin to allow the rate of internal supply of water from the cathode side to the anode side to be enhanced. 23. The direct oxidation fuel cell as defined in claim 22 wherein said membrane is substantially comprised of polyperfluorosulfonic acid. 24. The direct oxidation fuel cell as defined in claim 1 further comprising one or more layer components being disposed generally adjacent a cathode backing layer in an exterior portion of said cathode chamber that faces the ambient environment to control water loss, primarily in vapor form, from the cathode chamber. 25. The direct oxidation fuel cell as defined in claim 24 wherein one or more of said layer components is substantially porous. 26. The direct oxidation fuel cell as defined in claim 24 wherein one or more of said layer components is substantially hydrophobic, or has combined, hydrophilic/hydrophobic characteristics. 27. The direct oxidation fuel cell as defined in claim 1 further comprising a one or more layer components being disposed generally in said anode chamber to control water loss from said membrane through the anode aspect of the membrane. 28. The direct oxidation fuel cell as defined in claim 27 wherein said component in said anode chamber is a microporous layer that is comprised substantially of expanded PTFE. 29. The direct oxidation fuel cell as defined in claim 28 wherein said microporous layer that is comprised substantially of expanded PTFE, also includes embedded carbon microparticles. 30. The direct oxidation fuel cell as defined in claim 1 further comprising additional fuel delivery tools directed into the vapor gap in the anode chamber including one or more fuel injectors. 31. The direct oxidation fuel cell as defined in claim 1 further comprising means for heating liquid fuel in said fuel reservoir using catalytic combustion or electric heating. 32. The direct oxidation fuel cell as defined in claim 1 wherein said membrane is substantially comprised of an intrinsic proton conducting membrane. 33. The direct oxidation fuel cell as defined in claim 32 wherein said intrinsic proton conducting membrane is substantially comprised of polyperflourosulfonic acid. 34. The direct oxidation fuel cell as defined in claim 1 wherein said membrane does not require added liquid acid electrolyte and uses liquid water to achieve good protonic conductivity. 35. A direct oxidation fuel cell, comprising: (A) a membrane intimately interfacing with a catalyst layer along each of said membrane's major surfaces, having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said fuel cell; (C) a fuel chamber filled or fed directly with fuel, said anode chamber having no liquid outlet, (D) effective water supply from cathode to anode within said fuel cell, so that water management in said fuel cell is achieved without water collection from cathode to anode external to the active volume of the fuel cell; and (E) at least one gas exit port defined in said anode chamber such that gaseous anode products are released directly to the ambient environment and said gas exit port being located in close proximity to said anode aspect of the membrane and said gas exit port is at least one pinhole in said membrane that directs anodic gaseous product out of said fuel cell through the membrane and, in turn, through the cathode chamber. 36. A direct oxidation fuel cell, comprising: (A) a membrane intimately interfacing with a catalyst layer along each of said membrane's major surfaces, having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said fuel cell with an anode chamber being defined between said anode aspect of the membrane and an exterior portion of said cell housing; (C) said anode chamber filled or fed directly with neat (100%) or high concentration fuel/water mixture having zero or substantially low water content and said anode chamber having no liquid outlet; (D) effective water supply from cathode to anode within said fuel cell, so that water management in said fuel cell is achieved without water collection from the cathode and/or water transport from cathode to anode external to the active volume of the fuel cell; (E) a passive mass transport barrier disposed in said anode chamber, said passive transport barrier controlling a rate of fuel delivery to said catalyzed anode aspect of said fuel cell; and (F) an adjustable aperture means associated with said passive mass transport barrier such that fuel delivery through said mass transport barrier can be controlled, as well as shut-off completely, by the adjustment of said adjustable aperture means. 37. A direct oxidation fuel cell system, comprising: (A) one or more a direct oxidation fuel cell, each including a membrane that is sufficiently thin to allow a rate of internal supply of water from a cathode to an anode side of the fuel cell to be enhanced, said membrane intimately interfacing with a catalyst along each of said membranes' major surfaces, and having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said one or more fuel cells; (C) one or more fuel reservoirs providing a controlled feed of fuel to an anode aspect of one or more of said fuel cells through a passive mass transport barrier that defines the rate of fuel delivery of a level of about 10-50% higher than the rate of anodic consumption of methanol in the fuel cell in the anodic reactions of the membrane; and (D) an effective water supply from cathode to anode through said membrane wherein water management in said fuel cell is achieved without water transport from the cathode to the anode external to the active volume of the fuel cell. 38. A method of operating a direct oxidation fuel cell, comprising: providing a direct oxidation fuel cell having with a membrane that is sufficiently thin to allow a rate of internal supply of water from a cathode side to an anode side of the fuel cell to be enhanced, said membrane interfacing with a catalyst on each of the membranes' major surfaces; controlled feeding fuel to an anode aspect of said membrane, to a level of about 10-50% higher than the rate of anodic consumption of methanol in the fuel cell; and spontaneous flow of water back from the cathode aspect to the anode aspect across said membrane within said fuel cell whereby water management in said fuel cell is achieved without recirculation from the cathode to the anode external to the active volume of the fuel cell. 39. The method of operating a direct oxidation fuel cell as defined in claim 38 wherein said feeding of fuel is provided to achieve a predetermined limiting current density, while ensuring uniform current distribution. 40. The method as defined in claim 39 wherein said predetermined maximum limiting current density is determined by at least one of the following: about 100-200 mA/cm2 at cell operation temperature of about 10-30 deg.C.; on the order of about 150-300 mA/cm2 at cell operation temperature of about 40-60 deg.C.; and about 200-400 mA/cm2 at cell operation temperature of 60-80 deg.C. 41. A direct oxidation fuel cell system comprising: (A) membrane means intimately interfacing with a catalyst layer along each of the major surfaces of said membrane means, having an anode aspect and a cathode aspect; (B) means for enclosing said membrane means in a fuel cell housing having no liquid outlet in an anode chamber being defined between said anode aspect of the membrane means and an exterior portion of said cell housing; (C) means for dosing said anode aspect with neat (100%) or high concentration methanol with zero or substantially zero water content such that said methanol is face fed to the anode aspect and is consumed at a rate of fuel delivery of about 10-50% higher than a rate of anodic consumption of methanol in an anodic reaction; and (D) means for supplying water generated in a cathodic reaction across said membrane means to said anode chamber by providing a robust dense cathode backing and and a sufficiently thin membrane which allows substantially all of said water generated in said cathode reaction to be transported from cathode to anode without requiring water transport external to an active volume of the fuel cell. 42. The direct oxidation fuel cell as defined in claim 41 wherein said membrane means is a thickness of about 50 micrometers and is substantially comprised of polyperfluorosulfonic acid. 43. A direct oxidation fuel cell, comprising: (A) a membrane, sufficiently thin to allow a rate of internal supply of water from a cathode side to an anode side of the fuel cell to be enhanced, said membrane intimately interfacing with a catalyst layer along each of said membrane's major surfaces, having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said fuel cell; (C) a fuel chamber in fluid communication with said anode aspect, said fuel chamber having no liquid outlet, and being filled or fed with fuel and said fuel chamber having a passive mass transport barrier that is configured to define a rate of fuel delivery that is 1 to 1.5 times higher than a rate of anodic consumption of methanol in the fuel cell; and (D) effective water supply from cathode to anode within said fuel cell, so that water management in said fuel cell is achieved without water transport from cathode to anode external to the active volume of the fuel cell. 44. The direct oxidation fuel cell as defined in claim 43, wherein the fuel is neat methanol having substantially zero water content. 45. The direct oxidation fuel cell as defined in claim 43, wherein said passive mass transport barrier is disposed in a plane that is generally parallel to that of the anode aspect. 46. The direct oxidation fuel cell as defined in claim 43, wherein said rate of fuel delivery by said passive mass transport barrier is a defined rate calculated with reference to design cell current. 47. The direct oxidation fuel cell as defined in claim 46, wherein said defined rate is calculated such that fuel delivery is controlled to achieve a limiting cuffent density on the order of one of the following: about 100-200 mA/cm2 at cell operation temperature of about 30-40 deg.C; on the order of about 150-300 mA/cm2 at cell operation temperature of about 40-60 deg.C and about 200-400 mA/cm2 at cell operation temperature of 60-80 deg.C. 48. The direct oxidation fuel cell as defined in claim 46, wherein said rate of fuel delivery by said passive mass transport barrier corresponds to a rate of fuel consumption by the fuel cell, as gauged by the design cell current at a design point of operation, multiplied by a factor of between about 1.0 and 1.5. 49. The direct oxidation fuel cell as defined in claim 43, wherein said passive mass transport barrier is a pervaporation fuel delivery membrane that effects a phase change such that liquid fuel on transporting through said fuel delivery membrane is converted to a vaporous fuel. 50. The direct oxidation fuel cell as defined in claim 49, wherein said fuel delivery membrane effects a vapor delivery rate, as gauged by a design cell current at a design point of operation multiplied by a factor of between about 1.0 and 1.5. 51. The direct oxidation fuel cell as defined in claim 49, wherein a vapor chamber is defined in a gap between said fuel delivery membrane and said anode aspect of the membrane electrolyte, said vapor chamber maintaining a significant fraction of it's volume free of liquid. 52. The direct oxidation fuel cell as defined in claim 43, wherein said passive mass transport barrier is a microporous structure having perforations that deliver and direct liquid fuel to the anode aspect of the catalyzed membrane electrolyte at a defined rate. 53. The direct oxidation fuel cell as defined in claim 52, wherein said microporous structure is disposed in a plane that is generally parallel to that of the anode aspect. 54. The direct oxidation fuel cell as defined in claim 43, wherein said passive mass transport barrier is a solid porous plug having a pore network that provides for a capillary-force-controlled flow of fuel at the defined rate. 55. The direct oxidation fuel cell as defined in claim 43, wherein said fuel is up to 100% methanol. 56. The direct oxidation fuel cell as defined in claim 43, further comprising at least one gas exit port defined in said anode chamber such that gaseous anode products are released directly to the ambient environment, and said gas exit port being located in close proximity to said anode aspect of the catalyzed membrane. 57. The direct oxidation fuel cell as defined in claim 56, wherein said gas exit port is a vent in a carbon dioxide router device. 58. The direct oxidation fuel cell as defined in claim 43, wherein water generated in a reaction at the cathode aspect of the membrane electrolyte is supplied back from a cathode to anode side of said fuel cell at rate sufficient to provide an amount of water that is required for substantially complete anodic oxidation of fuel at the highest cell current capable. 59. The direct oxidation fuel cell as defined in claim 58, further comprising a wet-proofed cathode backing disposed in the cathode chamber, and a hydrophobic microporous layer, being substantially comprised of expanded PTFE, disposed generally between the cathode backing and the cathode aspect of the catalyzed membrane electrolyte, to enhance the rate of supply of water back from the cathode side of the fuel cell to the anode side of the fuel cell. 60. The direct oxidation fuel cell as defined in claim 59, wherein said microporous layer is robust bonded to the cathode aspect by hot-pressing under controlled humidity conditions. 61. The direct oxidation fuel cell as defined in claim 59, wherein said microporous layer is secured to said cathode aspect of the membrane electrolyte by compression across the cell thickness dimension of over 50 PSI, to establish substantially sustained adherence. 62. The direct oxidation fuel cell as defined in claim 59, wherein said microporous layer that is comprised substantially of expanded PTFE also includes embedded carbon microparticles. 63. The direct oxidation fuel cell as defined in claim 59, wherein said hydrophobic microporous layer is deposited directly onto the wet-proofed cathode backing. 64. The direct oxidation fuel cell as defined in claim 43, wherein said catalyzed membrane electrolyte is sufficiently thin to allow the rate of internal supply of water from the cathode side to the anode side to be enhanced. 65. The direct oxidation fuel cell as defined in claim 64, wherein said membrane electrolyte is substantially comprised of polyperfluorosulfonic acid. 66. The direct oxidation fuel cell as defined in claim 43, further comprising one or more layer components being disposed generally adjacent a cathode backing layer in an exterior portion of said cathode chamber that faces the ambient environment to control water loss, primarily in vapor form, from the cathode chamber. 67. The direct oxidation fuel cell as defined in claim 66, wherein one or more of said layer components is substantially porous. 68. The direct oxidation fuel cell as defined in claim 66, wherein one or more of said layer components is substantially hydrophobic, or has combined, hydro-philic/hydrophobic characteristics. 69. The direct oxidation fuel cell as defined in claim 43, further comprising a one or more layer components being disposed generally in said anode chamber to control water loss from said catalyzed membrane electrolyte through the anode aspect of the mem brane. 70. The direct oxidation fuel cell as defined in claim 69, wherein said component in said anode chamber is a microporous layer that is comprised substantially of expanded PTFE. 71. The direct oxidation fuel cell as defined in claim 70, wherein said microporous layer that is comprised substantially of expanded PTFE, also includes embedded carbon microparticles. 72. The direct oxidation fuel cell as defined in claim 43, further comprising additional fuel delivery tools directed into the vapor gap in the anode chamber including one or more fuel injectors. 73. The direct oxidation fuel cell as defined in claim 43, further comprising means for heating liquid fuel in said fuel reservoir using catalytic combustion or electric heating. 74. The direct oxidation fuel cell as defined in claim 43, wherein said membrane is substantially comprised of an intrinsic proton conducting membrane. 75. The direct oxidation fuel cell as defined in claim 74, wherein said intrinsic proton conducting membrane is substantially comprised of polyperflourosulfonic acid. 76. The direct oxidation fuel cell as defined in claim 43, wherein said membrane does not require added liquid acid electrolyte and uses liquid water to achieve good protonic conductivity. 77. A direct oxidation fuel cell system, comprising: (A) one or more a direct oxidation fuel cells, each including a membrane that is sufficiently thin to allow a rate of internal supply of water from a cathode to an anode side of the fuel cell to be enhanced, said membrane intimately interfacing with a catalyst along each of said membranes ' major surfaces, and having an anode aspect and a cathode aspect; (B) a fuel cell housing enclosing said one or more fuel cells; (C) one or more fuel reservoirs providing a controlled feed of fuel to an anode aspect of one or more of said fuel cells through a passive mass transport barrier that defines the rate of fuel delivery that is about 1.0 to 1.5 times higher than the rate of anodic consumption of methanol in the fuel cell in the anodic reactions of the membrane; and (D) an effective water supply from cathode to anode through said membrane wherein water management in said fuel cell is achieved without water transport from the cathode to the anode external to the active volume of the fuel cell. 78. A method of operating a direct oxidation fuel cell, comprising: providing a direct oxidation fuel cell with a membrane that is sufficiently thin to allow a rate of internal supply of water from a cathode side to an anode side of the fuel cell to be enhanced, said membrane interfacing with a catalyst on each of the membranes' major surfaces; controlled feeding fuel to an anode aspect of said membrane, to a level that is about 1.0 to 1.5 times higher than the rate of anodic consumption of methanol in the fuel cell; and spontaneous flow of water back from the cathode aspect to the anode aspect across said membrane within said fuel cell whereby water management in said fuel cell is achieved without recirculation from the cathode to the anode external to the active volume of the fuel cell. 79. The method of operating a direct oxidation fuel cell as defined in claim 78, wherein said feeding of fuel is provided to achieve a predetermined limiting current density, while ensuring uniform current distribution. 80. The method as defined in claim 79, wherein said predetermined limiting current density is determined by at least one of the following: about 100-200 mA/cm2 at cell operation temperature of about 30-40 deg.C; on the order of about 150-300 mA/cm2 at cell operation temperature of about 40-60 deg.C; and about 200-400 mA/cm2 at cell operation temperature of 60-80 deg.C. 81. A direct oxidation fuel cell system comprising: (A) membrane means intimately interfacing with a catalyst layer along each of the major surfaces of said membrane means, having an anode aspect and a cathode aspect; (B) means for enclosing said membrane means in a fuel cell housing having no liquid outlet in an anode chamber being defined between said anode aspect of the membrane means and an exterior portion of said cell housping; (C) means for dosing said anode aspect with neat (100%) or high concentration methanol with zero or substantially zero water content such that said methanol is face fed to the anode aspect and is consumed at a rate of fuel delivery that is 1.0 to 1.5 times higher than a rate of anodic consumption of methanol; and (D) means for supplying water generated in a cathodic reaction across said membrane means to said anode chamber by providing a robust dense cathode backing and a sufficiently thin membrane which allows substantially all of said water generated in said cathode reaction to be transported from cathode to anode without requiring water transport external to an active volume of the fuel cell. 82. The direct oxidation fuel cell as defined in claim 81 wherein said membrane is a thickness of about 50 micrometers and is substantially comprised of polyperfluorosulfonic acid.
