Abstract: A fuel cell, such as a polymer electrolyte fuel cell, includes an anode reactant supply plate, an anode current collector, a cathode reactant supply plate, and a cathode current collector. At least one of the anode reactant supply plate, the cathode reactant supply plate, the anode current collector and the cathode current collector is electrically separated into a number of segments, wherein each segment of at least a subgroup of segments is separately connected to an electronic drive and analysis circuitry which performs in parallel impedance measurement in a frequency range of 0.1 mHz to 50 kHz of the respective segments.

Abstract: A membrane electrode assembly includes a cathode layer, an anode layer, and a polymer electrolyte sandwiched between the cathode layer and the anode layer. The polymer electrolyte layer is a polymer film having a plurality of sections. The sections are radiation grafted and sulfonated, wherein the sections are separated from each other by separation bands. The separation bands are untreated sections of the polymer electrolyte layer.

Abstract: A fuel cell, such as a polymer electrolyte fuel cell, includes an anode reactant supply plate, an anode current collector, a cathode reactant supply plate, and a cathode current collector. At least one of the anode reactant supply plate, the cathode reactant supply plate, the anode current collector and the cathode current collector is electrically separated into a number of segments, wherein each segment of at least a subgroup of segments is separately connected to an electronic drive and analysis circuitry which performs in parallel impedance measurement in a frequency range of 0.1 mHz to 50 kHz of the respective segments.

Abstract: In a method for preparing a membrane to be assembled in a membrane electrode assembly, such as a polymer electrolyte membrane fuel cell, a base polymer film is irradiated with at least one of electromagnetic and particle radiation in order to form reactive centers within the polymer film. The irradiated film is exposed to a mixture of monomers amenable to radical polymerization to form a graft copolymer in the irradiated film. The mixture includes ?-methylstyrene and methacrylonitrile. The grafted film is sulfonated to introduce sulfonic acid sites providing ionic conductivity of the material.

Abstract: A block copolymer for use as a solid polymer electrolyte, said block copolymer having at least first and second segments, the first segments being hydrophilic segments provided with acidic substituents for proton transport and the second segments being hydrophobic segments having substantially no acidic substituents and serving for the mechanical integrity of the solid polymer electrolyte. Also described and claimed are an ion-conductive membrane made from block copolymers of the aforementioned kind as well as methods of preparing such block copolymers and membranes based thereon. The membranes have improved proton conductivity and improved mechanical properties in the presence of water making them particularly suitable for use in fuel cells.