Direct oxidation fuel cell operating with direct feed of concentrated fuel under passive water management

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.

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.

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.

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.

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.

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.

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.

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.

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.