Optimization of structure and design of membrane electrode assembly for DMFC

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30% enhancement in power output was successfully achieved by an employment of Pt thin film addition on to the electrode/electrolyte interface with a sputtering technique. The similar approach was conducted with Pt-Ru binary sputtering on the anode interface, and an optimum composition of the binary catalyst and also the optimum amount for higher power output were made clear. As a result of these investigations, DMFC power output with 0.22W/cm^2 was achieved. A condensed catalyst thin layer with Pt and Pt-Ru black catalyst on cathode and anode, respectively, was designed and prepared based on the above investigations, and we could successfully demonstrated a DMFC with a power output as high as 0.35W/cm^2.By employing a novel electrode structure with a porous carbon plate, reduction of the methanol crossover to 1/3-1/10 was successfully attained. And then, it made DMFC operation with high concentration methanol like 15-17M possible.For a practical MEA using Nafion 117 and 112, methanol crossover as a function of temperature, methanol concentration and current density was evaluated, and based on this, an empirical equation to calculate methanol crossover was proposed.The anode overvoltage was successfully reduced by the addition of TiO2, 8%, to the catalyst layer.As a novel solid electrolyte for high temperature, 200℃, and low humidity, Nafion impregnated with an ionic liquid, i.e., MPPTFSI etc., and a proton-containing inorganic compounds with NASICON-type structures were successfully prepared. The former showed electric conductivity 10^<-2> Scm^<-1> at 200℃, and suggested a proton conduction.A novel catalyst employing mesoporous carbon particles as support of Pt-Ru catalyst was prepared. It was succeeded to obtain fine particles with several nano-meter in size and highly distributed on the surface of the mesoporous carbon particles.