抄録
The effect of Nafion content and loading method in the catalyst layer of cathode for Direct Methanol Fuel Cell (DMFC) was investigated. The impedance of full cell and cathode are determined by ac impedance spectroscopy. The Nafion content improved the current density at cell voltage of 0.4 V up to 258 mA/cm2 at a content of 1.0 mg/cm2 in comparison with 128 mA/cm2 at a content of 0.5 mg/cm2. The increase in Nafion content was decreased the diameter of arc at the low frequency. The optimum value of Nafion content was 1.0mg/cm2. For the spray method electrode (SME), the cell performance and cathode performance using a dynamic hydrogen electrode (DHE) as a reference electrode was improved in comparison with those of the PME electrode by decreasing cathode potential. From the cathode ac impedance measurements, the diffusion resistance of the SME electrode was decreased compared with that of the PME electrode. The higher cell performance was mostly dependent on the diffusion resistance. The SME with porous structure and thin catalyst layer were showed by SEM and BET adsorption measurement. In addition, the structural model of cathode has been developed and experimentally verified with which fundamental calculations of the DMFC were carried out. The model provides information concerning on the influence of the operating and structural parameters.
