New Technologies of DMFC

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The fuel cells for liquid alcohol fuels are studied intensively. Alcohols are more suitable for fuels than hydrogen because we easily store and transport. In this project direct methanol fuel cells (DMFCs) and direct ethanol fuel cells are mainly investigated in order to support the efforts to develop their practical use. First the factors preventing the practical use of DMFCs are summarized as: (1) low efficiency for power generation, (2) low power density, (3) high material cost, (4) too large for portable applications, (5) toxicity of methanol. Then the basic 5 approaches were designed to solve the problems. They are : (1) reduction of the methanol cross over, (2) development of a high current density electrode and high temperature electrolyte materials, (3) reduction of the platinum loading on the DMFC electrodes, and development of new catalysis without containing precious metals, (4) development of MEMS fuel cells for miniaturization, (5) studying direct ethanol fuel cells.The fo … More llowing solutions for the 5 problems were obtained as the result of this project. (1) A new type of membrane namely the pore-filling membrane was developed, and its MEA gives high performance with high concentration methanol fuel (around 10M). (2) A novel DMFC with a porous carbon substrate was developed to reduce the methanol cross over, and the single cell showed a high I-V performance even at high methanol concentration (as high as 17M). (3) APt/SnOx catalyst was synthesized on a well controlled surface of carbon nano-tubes by self-organization. Such nano-structure is promising for the reduction of Pt loading in DMFCs. (4) Novel micro DMFCs based on MEMS technology were designed and fabricated. This technology reduces the number of the components in a DMFC and reduces the assembly cost as well as reduces their sizes. (5) A direct ethanol fuel cell is studied and the behavior of the acetaldehyde which is an intermediate product in the anode reaction was investigated. The knowledge obtained in this analysis contributes to the realization of direct ethanol fuel cells (DEFCs). Less