Abstract: A fuel cell system including a gas recycling and re-pressurizing assembly. In one embodiment, the fuel cell system includes a fuel cell stack, the stack having an oxygen outlet and an oxygen inlet. The fuel cell system additionally includes two gas/water separator tanks, each of the tanks containing a quantity of water and a quantity of oxygen gas. Both tanks are capable of being fluidly connected to either the oxygen inlet or the oxygen outlet of the fuel cell stack. In addition, the two tanks are connected to one another so that water may be transferred back and forth between the two tanks. The system also includes a pump for transferring water back and forth between the tanks.

Abstract: A fuel cell system including a gas recycling and re-pressurizing assembly. In one embodiment, the fuel cell system includes a fuel cell stack, the stack having an oxygen outlet and an oxygen inlet. The fuel cell system additionally includes two gas/water separator tanks, each of the tanks containing a quantity of water and a quantity of oxygen gas. Both tanks are capable of being fluidly connected to either the oxygen inlet or the oxygen outlet of the fuel cell stack. In addition, the two tanks are connected to one another so that water may be transferred back and forth between the two tanks. The system also includes a pump for transferring water back and forth between the tanks. In use, water is pumped from one of the tanks to the other until all of the oxygen gas present within the water-receiving tank is forced out of that tank and is conducted back to the oxygen inlet of the fuel cell stack.

Abstract: A fuel cell and method using the same. The fuel cell comprises a membrane electrode assembly, the membrane electrode assembly comprising a proton exchange membrane having a front face and a rear face. An anode is coupled to the front face of the proton exchange membrane, and a cathode is coupled to the rear face of the proton exchange membrane. A vapor diffusion chamber is positioned in the front of the anode, and a vapor transport member is positioned in front of the vapor diffusion chamber. The vapor transport member is substantially impermeable to an organic fuel/water mixture in a liquid phase but is permeable to the organic fuel/water mixture in a vapor phase. In operation, a liquid fuel mixture delivered to the vapor transport member evaporates from the vapor transport member and is delivered to the anode in vapor form.

Abstract: A corrosion resistant, electrically conductive, non-porous bipolar plate is made from titanium carbide for use in an eletrochemical device. The process involves blending titanium carbide powder with a suitable binder material, and molding the mixture, at an elevated temperature and pressure.

Abstract: Cation exchange membranes incorporating a thin layer of polymer having having a high ratio of backbone carbon atoms to cation exchange groups provide improved performance in direct methanol fuel cells.

Abstract: A gas sensor including an electrochemical sensor cell which has a anion-eange solid polymer electrolyte membrane with three attached electrodes is provided. The sensor cell contains no liquid electrolyte and is operated in the potentiostatic as well as the potentiodynamic modes to detect alkaline reactive gases, including vapors, such as hydrazines and derivatives thereof and ammonia. These sensor cells together with electronic circuitry, a pump and a power supply, fit into a compact, pocket-sized container to define the gas sensor of the invention which can detect traces of the above gases including 10 ppb of hydrazine and its derivatives and 10 ppm of ammonia. The invention includes the above gas sensor and the methods of operating same.

Abstract: A direct methanol fuel cell (DMFC) contains a membrane electrode assembly (MEA) including an anode porous electrode structure which can operate on a liquid or vapor methanol/water feed in the absence of a liquid electrolyte such as sulfuric acid, a proton-exchange membrane electrolyte, and a porous gas-diffusion cathode. The anode porous electrode structure includes a three-dimensional reduced (Pt--Ru)O.sub.x catalyst particle-ionomer composite structure, whereby the ionomer coats the individual particles and provides a mechanism for continuous proton transport throughout the composite structure, eliminating the need for a liquid acidic electrolyte. The partially reduced (Pt--Ru)O.sub.x particles are individually ionomer coated prior to anode fabrication. The anode porous electrode structure is subsequently bonded to one side of a thin sheet of a solid proton-conducting ionomer membrane and a cathode structure bonded to the opposite side of the membrane, to form a MEA.