摘要:
A fuel cell including an electrode assembly, a cell assembly mounted to the electrode assembly forming an anode and at least one cathode channel, and a flow facilitator located within each cathode channel. The flow facilitator functions as a wick during the operation of the fuel cell to drain fluid from the cathode channels. It also provides resistance to water vapor flow within the cathode channels, thereby increasing humidification of the fuel cell. Moreover, the flow facilitator increases residence time of oxidant within the cathode channels. The flow facilitator is preferably a thread made of any one or any combination of cotton, silk, fiberglass, nylon or polyester, and may be coated with polytetraflouroethylene. The flow facilitator may be a single element that is weaved in specific patterns through the cathode channels or it can include a plurality of elements, one element for each of the cathode channels. A fuel cell stack includes a plurality of fuel cells, each fuel cell formed by a bipolar plate, an electrode assembly with an electrolyte, and an anode channel. Each bipolar plate includes at least one cathode channel. The flow facilitator is weaved between and into a subset of the plurality of cathode channels.
摘要:
This invention relates to a method for preventing or retarding microbial or calcareous fouling of a conducting or semi-conducting surface in an aqueous environment. This method produces an effective concentration of hydrogen peroxide at or near the surface to be protected by applying a sufficient cathodic voltage and a sufficient cathodic current to electrochemically generate an effective concentration of hydrogen peroxide. This effective concentration is preferably produced at very low current densities, i.e., at densities of less than about 100 microamperes per square centimeter. This effective concentration is further preferably produced at cathodic voltages less than that required to generate hydrogen gas at the cathode.
摘要:
A method for catalyzing a gas diffusion electrode (GDE) with a catalytic material mixed with a solubilized electrolyte, where the electrolyte preferably comprises a perfluorocarbon sulfonic acid copolymer. The catalytic material and solubilized electrolyte are mixed to form a paste or the slurry, which is then applied layer by layer onto the catalyzable side of the GDE while the electrode is kept on a hot plate at a temperature of approximately 80.degree.-100.degree. C. The electrode and the catalyst layers are then dried in an oven at a temperature of about 100.degree. C. for about 10 minutes. The catalytic material preferably comprises a metal, such as platinum, and is further mixed with a supporting material comprising a high surface area carbon, resulting in a platinum-on-carbon mixture. A method according to the present invention avoids exposure of the high surface area catalytic material to the high temperatures of the conventional method, thereby keeping the maximum surface area of the catalyst available for the electrochemical reaction. Such gas diffusion electrodes are preferably used in operation of proton exchange membrane fuel cells without external humidification.
摘要:
The solid polymer fuel cell (SPFC), also known as the solid polymer electrolyte (SPE.RTM.) fuel cell, sold by Hamilton Standard, a Division of United Technologies Corporation, of Hartford, Conn., needs simplification for the fuel to become commercially viable. A simplified design is thus sought that would avoid prior humidification of reactants and the membrane, i.e., the electrolyte. A proton conducting material, such as perfluorocarbon copolymer, is deposited as the electrolyte on top of the catalytic side of the porous gas diffusion electrodes acting as anode and cathode. With sufficient deposits on both electrodes, it is then possible to avoid the use of electrolyte membrane which is used in the state-of-the-art solid polymer fuel cell design. The system operates at near ambient temperatures, pressures and at near stoichiometric reactant flows without requiring extra humidification of the reactant gases and the electrolyte.
摘要:
Simplified and improved solid polymer fuel cells for operation at near ambient conditions of temperature and pressure and without humidification are disclosed. In a first embodiment, a fuel cell is disclosed having two electrodes with opposing surfaces and an electrolyte comprising a solution of a proton conducting material deposited at the central portion of the surface of each electrode leaving the outer periphery of each electrode surface exposed. A slightly oversized non-conducting plastic type film having a central hole is located between and in contact with the electrodes, where its central hole surrounds and contacts the electrolyte deposits. The film is bonded with the electrodes and acts as a barrier for reactant cross-overs. In a second embodiment, the electrolyte deposit is thinner and located along the entire surface of the electrodes. A slightly oversized solid polymer electrolyte membrane is located between and is in contact with the electrolyte deposits. The membrane has a low gram equivalent weight, or is thinner but has a higher gram equivalent weight. Thus, the membrane easily transfers protons at a reduced internal electrolyte resistance, making operations possible at mild conditions without humidification.