Abstract: A catalyst layer including: a catalyst-supported carbon including a catalyst including platinum supported on a carbon carrier; and an ionomer, in which the catalyst-supported carbon has a mesopore having a pore diameter of from 2 nm to less than 10 nm in a pore distribution obtained by a nitrogen adsorption method, at least a part of the ionomer exists in the mesopore having a pore diameter of from 2 nm to less than 10 nm, a content of the ionomer with respect to 100 parts by mass of the carbon carrier is 100 parts by mass or more, and an occupancy rate of the ionomer in a total volume of the mesopore having a pore diameter of from 2 nm to less than 10 nm is 50% by volume or less.

Abstract: To provide methods for producing a liquid composition, a coating liquid for a catalyst layer and a membrane electrode assembly, capable of making cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer. A copolymer having a structural unit represented by —[CF2—CF{(OCF2CFX)mOp(CF2)nSO3H}]— (wherein X: F or CF3, m: 1 to 3, p: 0 or 1, and n: an integer of 1 to 12) and a structural unit derived from tetrafluoroethylene, is dispersed in a medium containing water and a hydrocarbon-type alcohol (but not including a fluorinated solvent) to prepare a dispersion wherein the concentration of the copolymer is from 13 to 26 mass %, and the dispersion and a fluorinated solvent are mixed so that the sum of the concentration of the copolymer and the concentration of the fluorinated solvent becomes to be from 17 to 35 mass %, to prepare a liquid composition.

Abstract: To provide a polymer electrolyte fuel cell having a high cell voltage. A polymer electrolyte fuel cell 1 comprising a membrane/electrode assembly 10 having a cathode catalyst layer 20, an anode catalyst layer 22 and a polymer electrolyte membrane 24 disposed between the cathode catalyst layer 20 and the anode catalyst layer 22, a porous first separator 12 disposed on the cathode catalyst layer 20 side of the membrane/electrode assembly 10, a second separator 18 disposed on the anode catalyst layer 22 side of the membrane/electrode assembly 10; and a cathode interlayer 14 disposed between the cathode catalyst layer 20 and the first separator 12 so as to be in direct contact with them, wherein the cathode interlayer 14 contains carbon fibers having an average fiber diameter of from 30 to 300 nm and an ion exchange resin.

Abstract: To provide a method for producing a liquid composition or a coating liquid for forming a catalyst layer, which can make cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer; and a method for producing a membrane electrode assembly, which can make cracking less likely to occur at the time of forming the catalyst layer or the solid polymer electrolyte membrane.

Abstract: To provide methods for producing a liquid composition, a coating liquid for a catalyst layer and a membrane electrode assembly, capable of making cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer. A copolymer having a structural unit represented by —[CF2—CF{(OCF2CFX)mOp(CF2)nSO3H}]— (wherein X: F or CF3, m: 1 to 3, p: 0 or 1, and n: an integer of 1 to 12) and a structural unit derived from tetrafluoroethylene, is dispersed in a medium containing water and a hydrocarbon-type alcohol (but not including a fluorinated solvent) to prepare a dispersion wherein the concentration of the copolymer is from 13 to 26 mass %, and the dispersion and a fluorinated solvent are mixed so that the sum of the concentration of the copolymer and the concentration of the fluorinated solvent becomes to be from 17 to 35 mass %, to prepare a liquid composition.

Abstract: To provide a method for producing a liquid composition or a coating liquid for forming a catalyst layer, which can make cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer; and a method for producing a membrane electrode assembly, which can make cracking less likely to occur at the time of forming the catalyst layer or the solid polymer electrolyte membrane.

Abstract: To provide a process for producing a membrane/electrode assembly for a polymer electrolyte fuel cell, by which the effect of improving power generation performance by providing an interlayer between a catalyst layer and a gas diffusion layer is sufficiently exhibited, and a paste for forming an interlayer suitable for the production process. A process for producing a membrane/electrode assembly for a polymer electrolyte fuel cell, comprising (a) a step of forming a first wet film 134 by coating the surface of a first carrier film 50 with a paste for forming an interlayer, said paste comprising a carbon material, a polymer and a liquid medium and having a viscosity of from 250 to 450 mPa·s at a shear rate of 200 (1/s) as measured at 25° C. by using an RE550 viscometer (manufactured by TOKI SANGYO CO., LTD.

Abstract: A process is provided whereby a membrane/electrode assembly for polymer electrolyte fuel cells whereby a high output voltage is obtainable within a wide range of current densities.

Abstract: To provide a polymer electrolyte fuel cell having a high cell voltage. A polymer electrolyte fuel cell 1 comprising a membrane/electrode assembly 10 having a cathode catalyst layer 20, an anode catalyst layer 22 and a polymer electrolyte membrane 24 disposed between the cathode catalyst layer 20 and the anode catalyst layer 22, a porous first separator 12 disposed on the cathode catalyst layer 20 side of the membrane/electrode assembly 10, a second separator 18 disposed on the anode catalyst layer 22 side of the membrane/electrode assembly 10; and a cathode interlayer 14 disposed between the cathode catalyst layer 20 and the first separator 12 so as to be in direct contact with them, wherein the cathode interlayer 14 contains carbon fibers having an average fiber diameter of from 30 to 300 nm and an ion exchange resin.

Abstract: A membrane electrode assembly less susceptible to flooding or shortcircuiting caused by piercing of carbon fibers of a gas diffusion layer to a polymer electrolyte membrane is provided, containing a cathode having a catalyst layer and a gas diffusion layer, an anode having a catalyst layer and a gas diffusion layer, and a polymer electrolyte membrane interposed between the catalyst layer of the cathode and the catalyst layer of the anode, wherein each of the cathode and the anode further has a protective layer containing carbon fibers having an average fiber diameter of from 1 to 30 ?m and a fluorinated ion exchange resin, between the catalyst layer and the gas diffusion layer, and the mass ratio (F/C) of the fluorinated ion exchange resin (F) to the carbon fibers (C) contained in the protective layer is from 0.05 to 0.30.

Abstract: To provide a membrane/electrode assembly for polymer electrolyte fuel cells, capable of achieving high power generation performance under low or no humidity operation conditions, and a process for producing a cathode for polymer electrolyte fuel cells. A membrane/electrode assembly 10, comprising: an anode 20 having a catalyst layer 22 and a gas diffusion layer 28, a cathode 30 having a catalyst layer 32 and a gas diffusion layer 38, and a polymer electrolyte membrane 40 interposed between the catalyst layer 22 of the anode 20 and the catalyst layer 32 of the cathode, wherein the cathode 30 has, between the catalyst layer 32 and the gas diffusion layer 38, a first interlayer 36 comprising carbon fibers (C1) and a fluorinated ion exchange resin (F1), and a second interlayer 34 comprising carbon fibers (C2) and a fluorinated ion exchange resin (F2), in this order from the gas diffusion layer 38 side.

Abstract: A solid polymer electrolyte material made of a copolymer comprising a repeating unit based on a fluoromonomer A which gives a polymer having an alicyclic structure in its main chain by radical polymerization, and a repeating unit based on a fluoromonomer B of the following formula (1): CF2?CF(Rf)jSO2X??(1) wherein j is 0 or 1, X is a fluorine atom, a chlorine atom or OM {wherein M is a hydrogen atom, an alkali metal atom or a group of NR1R2R3R4 (wherein each of R1, R2, R3 and R4 which may be the same or different, is a hydrogen atom or a monovalent organic group)}, and Rf is a C1-20 polyfluoroalkylene group having a straight chain or branched structure which may contain ether oxygen atoms.

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: To provide a membrane/electrode assembly for polymer electrolyte fuel cells, capable of achieving high-power generation performance under low or no humidity operation conditions, and a process for producing a cathode for polymer electrolyte fuel cells. A membrane/electrode assembly 10, comprising: an anode 20 having a catalyst layer 22 and a gas diffusion layer 28, a cathode 30 having a catalyst layer 32 and a gas diffusion layer 38, and a polymer electrolyte membrane 40 interposed between the catalyst layer 22 of the anode 20 and the catalyst layer 32 of the cathode, wherein the cathode 30 has, between the catalyst layer 32 and the gas diffusion layer 38, a first interlayer 36 comprising carbon fibers (C1) and a fluorinated ion exchange resin (F1), and a second interlayer 34 comprising carbon fibers (C2) and a fluorinated ion exchange resin (F2), in this order from the gas diffusion layer 38 side.

Abstract: A solid polymer electrolyte material made of a s copolymer comprising a repeating unit based on a fluoromonomer A which gives a polymer having an alicyclic structure in its main chain by radical polymerization, and a repeating unit based on a fluoromonomer B of the following formula (1): CF2?CF(Rf)jSO2X??(1) wherein j is 0 or 1, X is a fluorine atom, a chlorine atom or OM {wherein M is a hydrogen atom, an alkali metal atom or a group of NR1R2R3R4 (wherein each of R1, R2, R3 and R4 which may be the same or different, is a hydrogen atom or a monovalent organic group)}, and Rf is a C1-20 polyfluoroalkylene group having a straight chain or branched structure which may contain ether oxygen atoms.

Abstract: A solid polymer electrolyte material made of a copolymer comprising a repeating unit based on a fluoromonomer A which gives a polymer having an alicyclic structure in its main chain by radical polymerization, and a repeating unit based on a fluoromonomer B of the following formula (1): CF2?CF(Rf)jSO2X??(1) wherein j is 0 or 1, X is a fluorine atom, a chlorine atom or OM {wherein M is a hydrogen atom, an alkali metal atom or a group of NR1R2R3R4 (wherein each of R1, R2, R3 and R4 which may be the same or different, is a hydrogen atom or a monovalent organic group)}, and Rf is a C1-20 polyfluoroalkylene group having a straight chain or branched structure which may contain ether oxygen atoms.

Abstract: In the production of a membrane/electrode assembly 10, a first catalyst layer 22 (a second catalyst layer 34) is formed by a process comprising steps (a) and (b). (a) A step of applying a coating fluid comprising a catalyst and an ion-exchange resin, on a substrate to form a coating fluid layer. (b) A step of disposing a reinforcing layer 24 (34) on the coating fluid layer formed in the step (a) and then, drying the coating fluid layer to form a first catalyst layer 22 (a second catalyst layer 34) The process provides a catalyst layer whereby defects such as cracks are scarcely formed in the catalyst layer, and the bond strength is high at the interface between the catalyst layer and a reinforcing layer and at the interface between the catalyst layer and a polymer electrolyte membrane.

Abstract: Provided are a process for producing a membrane/electrode assembly for a polymer electrolyte fuel cell and a process for producing a polymer electrolyte fuel cell, capable of achieving a high output voltage in a wide current density range. At least one of an anode and a cathode in a membrane/electrode assembly for a polymer electrolyte fuel cell is formed through a catalyst layer forming step of applying a first coating fluid containing a catalyst and an ion exchange resin, onto a substrate to form a catalyst layer; a gas diffusion layer forming step of applying a second coating fluid containing carbon fibers and an ion exchange resin, onto the catalyst layer to form a gas diffusion layer to serve as an outermost layer of the membrane/electrode assembly for the polymer electrolyte fuel cell; and a peeling step of peeling the substrate off from the catalyst layer.

Abstract: A solid polymer electrolyte material made of a copolymer comprising a repeating unit based on a fluoromonomer A which gives a polymer having an alicyclic structure in its main chain by radical polymerization, and a repeating unit based on a fluoromonomer B of the following formula (1): CF2?CF(Rf)jSO2X ??(1) wherein j is 0 or 1, X is a fluorine atom, a chlorine atom or OM {wherein M is a hydrogen atom, an alkali metal atom or a group of NR1R2R3R4 (wherein each of R1, R2, R3 and R4 which may be the same or different, is a hydrogen atom or a monovalent organic group)}, and Rf is a C1-20 polyfluoroalkylene group having a straight chain or branched structure which may contain ether oxygen atoms.

Abstract: A solid polymer electrolyte material made of a copolymer comprising a repeating unit based on a fluoromonomer A which gives a polymer having an alicyclic structure in its main chain by radical polymerization, and a repeating unit based on a fluoromonomer B of the following formula (1): CF2?CF(Rf)jSO2X??(1) wherein j is 0 or 1, X is a fluorine atom, a chlorine atom or OM {wherein M is a hydrogen atom, an alkali metal atom or a group of NR1R2R3R4 (wherein each of R1, R2, R3 and R4 which may be the same or different, is a hydrogen atom or a monovalent organic group)}, and Rf is a C1-20 polyfluoroalkylene group having a straight chain or branched structure which may contain ether oxygen atoms.