Abstract: A composite membrane is provided in which a porous substrate is impregnated with a polymeric composition comprising various combinations of .alpha.,.beta.,.beta.-trifluorostyrene, substituted .alpha.,.beta.,.beta.-trifluorostyrene and ethylene-based monomeric units. Where the polymeric composition includes ion-exchange moieties, the resultant composite membranes are useful in electrochemical applications, particularly as membrane electrolytes in electrochemical fuel cells.

Abstract: An electrochemical fuel cell assembly comprises a pair of separator layers and a membrane electrode assembly interposed between the separator layers. The membrane electrode assembly comprises a pair of electrodes and an ion exchange membrane interposed therebetween, the electrodes having electrocatalyst associated therewith defining an electrochemically active area. Each of the separator layers comprises one or more reactant stream passages in fluid communication with one of the electrodes. At least one of the separator layers further comprises one or more coolant stream passages which do not superpose the electrochemically active area of the adjacent membrane electrode assembly, and are fluidly isolated from the reactant stream passages.

Abstract: A method and apparatus are provided for starting and operating an electric power generation system comprising an electrochemical fuel cell stack for supplying electric current to an external electrical circuit. The stack comprises at least one fuel cell comprising a membrane electrode assembly comprising an anode, a cathode, and a water permeable ion exchange membrane interposed between the anode and the cathode. A fuel stream and an oxidant stream are each flowable to the fuel cell. At least a portion of the membrane electrode assembly has a temperature below the freezing temperature of water. The supply of electric current to the external circuit from the fuel cell stack is commenced such that the temperature of the membrane electrode assembly exceeds the freezing temperature of water.

Abstract: An electrode comprises a first catalytic component active at gas-phase reaction sites and a second catalytic component active at electrochemical reaction sites wherein each catalytic component is present either as a separate layer, or a single mixed layer or a combination of a separate layer and a single mixed layer. The electrode has an improved tolerance to poisons such as carbon monoxide and carbon dioxide.

Abstract: An electrochemical fuel cell stack includes a plurality of fuel cell assemblies interposed between a pair of end plate assemblies. The mechanism for securing the stack in its compressed, assembled state includes at least one compression band which circumscribes the end plate assemblies and interposed fuel cell assemblies of the stack. Preferably, at least one of the end plate assemblies comprises a resilient member which cooperates with each compression band to urge the first end plate assembly toward the second end plate assembly, thereby applying compressive force to the fuel cell assemblies to promote sealing and electrical contact between the layers forming the fuel cell stack.

Abstract: Polymeric compositions are derived from copolymers of .alpha.,.beta.,.beta.-trifluorostyrene with a variety of substituted .alpha.,.beta.,.beta.-trifluorostyrenes. These compositions are suitable for use as membranes, particularly as ion-exchange membranes, and most particularly as solid polymer electrolytes in electrochemical applications, such as, for example, electrochemical fuel cells.

Abstract: A fuel cell assembly within an electrochemical fuel cell stack has an anode layer and a cathode layer. A cooling layer is disposed adjacent the fuel cell assembly. Each layer comprises channels for directing a fluid stream from an inlet to a an outlet. The coolant stream channels extend such that, in operation, the coolest region of the cooling layer coincides with the region of the cathode layer having the highest concentration of oxygen (and/or the lowest water content), and the warmest region of the cooling layer coincides with the region of the cathode layer having the lowest concentration of oxygen (and/or the highest water content).

Abstract: A method and apparatus detects and locates perforations in membranes used in electrochemical cells. The membrane has first and second oppositely facing major planar surfaces. The first surface is exposed to a first reactant fluid, preferably a gaseous mixture comprising hydrogen, while the second surface is exposed to a second reactant fluid, preferably ambient air comprising oxygen. The first and second reactant fluids are substantially fluidly isolated from each other by the membrane when no perforations are present in the membrane. The first reactant fluid contacts the second reactant fluid when at least one perforation is present in the membrane. The first and second reactant fluids exothermically react upon contact, preferably in the presence of a catalyst, to generate heat, which is then detected using an infrared thermal detector or thermal imaging device or a layer of thermally sensitive film positioned in proximity with the membrane.

Abstract: An edge manifold assembly conducts, introduces and receives reactant and coolant streams to and from an electrochemical fuel cell stack. The assembly comprises a plurality of manifold plates. Each of the fuel cells has a single manifold plate or at least three manifold plates attached thereto. Each of the manifold plates has at least one manifold opening formed therein for containing a fluid and at least one channel formed therein for effecting fluid communication between the manifold opening and the fuel cell to which the manifold plate is attached.

Abstract: An apparatus for the two-stage selective oxidation of carbon monoxide to carbon dioxide in a fuel stream comprising hydrogen and carbon monoxide. The apparatus includes primary and secondary reaction chambers, which deliver a hydrogen-rich outlet gas stream having a carbon monoxide concentration of less than about 5 ppm. When an increase in the carbon monoxide concentration in the outlet stream of the primary reaction chamber is detected, then the flow through the primary reaction chamber is reversed. The selective oxidizer employs a temperature-based control strategy as an oxygen-containing gas stream flow rate adjustment around the flow rate initially set in direct proportion to the fuel gas stream flow rate. The control strategy regulates the amount of oxygen-containing gas mixed with the gaseous fuel stream as a function of the difference between the temperature at a location at or near the end of the primary reaction chamber and the temperature at the outlet of the primary reaction chamber.

Abstract: An electrochemical fuel cell assembly with compliant compression mechanism includes a first plate, a second plate, and at least one membrane electrode assembly disposed between the first and second plates. Compliant compression members, such as twisted wire springs or ribbon springs, extend between the first and second plates such that the compression members urge the first plate toward said second plate to compress each membrane electrode assembly interposed between the plates. In operation, compressive force is applied by the compression members to each membrane electrode assembly to maintain electrical conductivity.

Abstract: Sulfonyl fluoride substituted .alpha.,.beta.,.beta.-trifluorostyrene monomers are disclosed. The monomers are incorporated into polymeric compositions which are conveniently hydrolyzed to produce polymeric compositions which include ion-exchange moieties. The resulting compositions which include ion-exchange moieties are particularly suitable for use as solid polymer electrolytes in electrochemical applications, such as, for example, electrochemical fuel cells.

Abstract: In an electrochemical fuel cell, a sufficient quantity of catalyst, effective for promoting the reaction of reactant supplied to an electrode, is disposed within the volume of the electrode so that a reactant introduced at a first major surface of the electrode is substantially completely reacted upon contacting the second major surface. Crossover of reactant from one electrode to the other electrode through the electrolyte in an electrochemical fuel cell is thereby reduced.

Abstract: Sulfonyl fluoride substituted .alpha.,.beta.,.beta.-trifluorostyrene monomers are disclosed. The monomers are incorporated into polymeric compositions which are conveniently hydrolyzed to produce polymeric compositions which include ion-exchange moieties. The resulting compositions which include ion-exchange moieties are particularly suitable for use as solid polymer electrolytes in electrochemical applications, such as, for example, electrochemical fuel cells.

Abstract: A fuel cell assembly within an electrochemical fuel cell stack has a cooling jacket disposed adjacent the cathode layer. The cooling layer comprises a coolant stream inlet, a coolant stream outlet, and at least one channel for directing a coolant stream from the coolant stream inlet to the coolant stream outlet. The coolant stream channels extend such that the coolest region of the cooling layer substantially coincides with the region of the adjacent cathode layer having the highest concentration of oxygen (and also the lowest water content), and the warmest region of the cooling layer substantially coincides with the region of the adjacent cathode layer having the lowest concentration of oxygen (and also the highest water content).

Abstract: An embossed fluid flow field plate for electrochemical cells comprises two sheets of compressible, electrically conductive material. Each sheet has two oppositely facing major surfaces. At least one of the major surfaces has an embossed surface which has a fluid inlet formed therein. The embossed surface has at least one open-faced channel embossed therein extending from the fluid inlet for conducting pressurized fluid introduced at the fluid inlet. A metal sheet is interposed between each of the compressible sheets. The compressible, electrically conductive sheet preferably comprises graphite foil. A method of fabricating an embossed separator plate for use in conjunction with an electrochemical fuel cell comprises (1) providing two sheets of compressible, electrically conductive sheet material, (2) interposing a metal sheet between each of the compressible sheets, and (3) embossing an open-faced channel in at least one of the surfaces of the sheets facing away from the metal sheet.

Abstract: An embossed fluid flow field plate for electrochemical cells comprises two sheets of compressible, electrically conductive material. Each sheet has two oppositely facing major surfaces. At least one of the major surfaces has an embossed surface which has a fluid inlet formed therein. The embossed surface has at least one open-faced channel embossed therein extending from the fluid inlet for conducting pressurized fluid introduced at the fluid inlet. A metal sheet is interposed between each of the compressible sheets. The compressible, electrically conductive sheet preferably comprises graphite foil.

Abstract: An apparatus and method are provided for the two-stage selective oxidation of carbon monoxide to carbon dioxide in a fuel stream comprising hydrogen and carbon monoxide. The apparatus includes primary and secondary reaction chambers, which deliver a hydrogen-rich outlet gas stream having a carbon monoxide concentration of less than about 5 ppm. When an increase in the carbon monoxide concentration in the outlet stream of the primary reaction chamber is detected, then the flow through the primary reaction chamber is reversed. The selective oxidizer employs a temperature-based control strategy as an oxygen-containing gas stream flow rate adjustment around the flow rate initially set in direct proportion to the fuel gas stream flow rate.

Abstract: An edge manifold assembly conducts, introduces and receives reactant and coolant streams to and from an electrochemical fuel cell stack. The assembly comprises a plurality of manifold plates. Each of the fuel cells has a pair of manifold plates attached thereto. Each of the manifold plates has at least one manifold opening formed therein for containing a fluid and at least one channel formed therein for effecting fluid communication between the manifold opening and the fuel cell to which the manifold plate is attached.

Abstract: Polymeric compositions are derived from copolymers of .alpha.,.beta., .beta.-trifluorostyrene with a variety of substituted .alpha.,.beta.,.beta.-trifluorostyrenes. These compositions are suitable for use as membranes, particularly as ion-exchange membranes, and most particularly as solid polymer electrolytes in electrochemical applications, such as, for example, electrochemical fuel cells.