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Fabrication of mDMFC and Effect of Methanol Modification on its PerformanceLu, Chang-Wei 21 August 2012 (has links)
Direct methanol fuel cell (DMFC) were characterized with low operation temperature, high energy density, rapid activation, easy to obtain, easy to carry, safety, stability and low pollution. Therefore, DMFCs were thought as the next generation of power suppliers to replace lithium battery in the future. In order to meet the miniaturization demand of portable electronic devices, this research tried to fabricate a £gDMFC, simplify component, and lower cost by using MEMS technique. This research used TMAH etching, PEACE, and KOH etching, CNT growth technique to fabricate the hill-like diffusion layer (HDL) electrode which combined the channel structure and through-hole silicon (THS) electrode.
Another emphasis of this research was to improve the bubble cover problem for £gDMFCs. The bubble cover problem resulted from the CO2 bubble generated in methanol oxidation reaction difficultly removed and resulted in adverse effect for reaction. This research tried to use the surfactants which used in electroforming to improve the bubble cover problem by improvement surface tension of fuel.
Experiments show that using the HDL electrode in anode and the THS electrode in cathode would get the maximum power density (0.186 mW/cm2). The powder density of the design £gDMFC is 10 and 2.5 times larger than the one with pure carbon paper electrodes and the HDL electrodes. Surfactant MA was suitable as a wetting of methanol. Bubble size could reduce 1/2 to 1/3 and bubble cover area could reduce 20% by adding MA. Add MA in the fuel cell could help the bubbles remove to avoid the bubble cover problem. Though MA addition would have the adverse effect for methanol reaction, could get the stabile voltage and extend the discharge time.
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