Abstract: An electrolyte membrane is prepared from a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer with a cation-exchange group. The liquid composition is preferably one containing water, a carbonate of cerium or manganese, and a polymer with a cation-exchange group, and a cast film thereof is used as an electrolyte membrane to prepare a membrane-electrode assembly. The present invention successfully provides a membrane-electrode assembly for polymer electrolyte fuel cells being capable of generating the electric power in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas, and being capable of stably generating the electric power over a long period of time.

Abstract: A process comprising: providing a substrate with a catalyst layer thereon; depositing a first ionomer overcoat layer over the catalyst layer, the first ionomer overcoat layer comprising an ionomer and a first solvent; drying the first ionomer overcoat layer to provide a first electrode ionomer overcoat layer; depositing a second ionomer overcoat layer over the first electrode ionomer overcoat layer, and wherein the second ionomer overcoat layer comprises an ionomer and a second solvent.

Abstract: An electrolyte membrane which comprises a cation exchange membrane made of a polymer having cation exchange groups and contains cerium ions is used as an electrolyte membrane for a polymer electrolyte fuel cell. In a case where the cation exchange membrane has sulfonic acid groups, the sulfonic acid groups are ion-exchanged, for example, with cerium ions so that cerium ions are contained preferably in an amount of from 0.3 to 20% of —SO3? groups contained in the cation exchange membrane. A membrane for a polymer electrolyte fuel cell capable of power generation in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas and capable of stable power generation over a long period of time, can be provided.

Abstract: An electrolyte membrane is prepared from a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer with a cation-exchange group. The liquid composition is preferably one containing water, a carbonate of cerium or manganese, and a polymer with a cation-exchange group, and a cast film thereof is used as an electrolyte membrane to prepare a membrane-electrode assembly. The present invention successfully provides a membrane-electrode assembly for polymer electrolyte fuel cells being capable of generating the electric power in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas, and being capable of stably generating the electric power over a long period of time.

Abstract: An electrolyte membrane is prepared from a liquid composition comprising at least one member selected from the group consisting of trivalent cerium, tetravalent cerium, bivalent manganese and trivalent manganese; and a polymer with a cation-exchange group. The liquid composition is preferably one containing water, a carbonate of cerium or manganese, and a polymer with a cation-exchange group, and a cast film thereof is used as an electrolyte membrane to prepare a membrane-electrode assembly. The present invention successfully provides a membrane-electrode assembly for polymer electrolyte fuel cells being capable of generating the electric power in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas, and being capable of stably generating the electric power over a long period of time.

Abstract: To provide a membrane/electrode assembly and a method for operating a polymer electrolyte fuel cell, whereby power generation will not be terminated even when the power generation is initiated in such an environment that the temperature of the membrane/electrode assembly is at most 0° C. A membrane/electrode assembly 10 for polymer electrolyte fuel cells, which comprises an anode 13 and a cathode 14 each having a catalyst layer 11 containing a proton-conductive fluoropolymer (A), and a polymer electrolyte membrane 15 containing a proton-conductive fluoropolymer (B), disposed between the anode 13 and the cathode 14, wherein each of the above proton-conductive fluoropolymer (A) and the above proton-conductive fluoropolymer (B) has an ion exchange capacity of from 1.4 to 1.8 meq/g dry resin, and each of the above proton-conductive fluoropolymer (A) and the above proton-conductive fluoropolymer (B) has a water content of at most 150 mass %.

Abstract: To provide a membrane/electrode assembly for a polymer electrolyte fuel cell which has a high power generation performance in an environment ranging from a low humidity to a high humidity and is scarcely susceptible to deterioration in the performance of the electrode even when fuel becomes deficient.

Abstract: To provide a membrane/electrode assembly and a method for operating a polymer electrolyte fuel cell, whereby power generation will not be terminated even when the power generation is initiated in such an environment that the temperature of the membrane/electrode assembly is at most 0° C. A membrane/electrode assembly 10 for polymer electrolyte fuel cells, which comprises an anode 13 and a cathode 14 each having a catalyst layer 11 containing a proton-conductive fluoropolymer (A), and a polymer electrolyte membrane 15 containing a proton-conductive fluoropolymer (B), disposed between the anode 13 and the cathode 14, wherein each of the above proton-conductive fluoropolymer (A) and the above proton-conductive fluoropolymer (B) has an ion exchange capacity of from 1.4 to 1.8 meq/g dry resin, and each of the above proton-conductive fluoropolymer (A) and the above proton-conductive fluoropolymer (B) has a water content of at most 150 mass %.

Abstract: A process comprising: providing a substrate with a catalyst layer thereon; depositing a first ionomer overcoat layer over the catalyst layer, the first ionomer overcoat layer comprising an ionomer and a first solvent; drying the first ionomer overcoat layer to provide a first electrode ionomer overcoat layer; depositing a second ionomer overcoat layer over the first electrode ionomer overcoat layer, and wherein the second ionomer overcoat layer comprises an ionomer and a second solvent.

Abstract: An electrolyte membrane which comprises a cation exchange membrane made of a polymer having cation exchange groups and contains cerium ions is used as an electrolyte membrane for a polymer electrolyte fuel cell. In a case where the cation exchange membrane has sulfonic acid groups, the sulfonic acid groups are ion-exchanged, for example, with cerium ions so that cerium ions are contained preferably in an amount of from 0.3 to 20% of —SO3? groups contained in the cation exchange membrane. A membrane for a polymer electrolyte fuel cell capable of power generation in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas and capable of stable power generation over a long period of time, can be provided.

Abstract: A membrane-electrode assembly for a polymer electrolyte fuel cell, which comprises an anode and a cathode each having a catalyst layer containing a catalyst powder and an ion exchange resin, and an electrolyte membrane made of an ion exchange membrane disposed between the anode and the cathode, characterized in that the catalyst layer of the anode contains a catalyst powder having a platinum-cobalt alloy supported on a carbon carrier.

Abstract: An electrode for a polymer electrolyte fuel cell, which is a porous gas diffusion electrode comprising a catalyst powder and an ion exchange resin, wherein a solvent-soluble fluorine-containing polymer having substantially no ion exchange groups exists at least at a part of the inner surface of pores of the electrode.

Abstract: An electrode for a polymer electrolyte fuel cell, which is a porous gas diffusion electrode comprising a catalyst powder and an ion exchange resin, wherein a solvent-soluble fluorine-containing polymer having substantially no ion exchange groups exists at least at a part of the inner surface of pores of the electrode.

Abstract: An electrode for a polymer electrolyte fuel cell, which is a porous gas diffusion electrode comprising a catalyst powder and an ion exchange resin, wherein a solvent-soluble fluorine-containing polymer having substantially no ion exchange groups exists at least at a part of the inner surface of pores of the electrode.

Abstract: A polymer electrolyte fuel cell comprising an ion exchange membrane, and a cathode and an anode facing each other via the ion exchange membrane, wherein the cathode comprises an ion exchange resin and an electrode catalyst having platinum or a platinum alloy deposited on a carbon support which has an average lattice spacing of (002) d002 calculated by the X-ray diffraction data, of from 0.340 to 0.362 nm, a microcrystallite size Lc of from 0.6 to 4 nm and a specific surface area of from 260 to 800 m2/g.

Abstract: A polymer electrolyte fuel cell comprising a membrane-form solid polymer electrolyte, a fuel electrode disposed on one side of the polymer electrolyte, and an air electrode disposed on the other side of the polymer electrolyte, wherein each of the fuel electrode and the air electrode is made of a gas diffusion electrode having a catalyst covered with a fluorocarbon ion exchange resin, and the ion exchange capacity of the ion exchange resin of the fuel electrode is larger than the ion exchange capacity of the ion exchange resin of the air electrode.