Properties and DMFC Performance of Nafion/mordenite Composite Membrane Fabricated by Solution-casting Method with Different Solvent Ratio

The effect of alcohol ratio in solution casting of composite membranes is one of the important factors to their good properties for direct methanol fuel cell (DMFC). The investigation was focused on the effect of alcohol ratio (methanol/ethanol mixture) during the fabrication process on the membrane properties, morphology, chemical resistance, water uptake, proton conductivity and methanol permeability. Alcohol mixture with proportion of 0 – 5 volume ratio was varied in order to prepare the composite membranes. It was found that the alcohol ratio had insignificant effect on the homogeneity of the composite membranes as the layers of polymer rich and mordenite rich were formed. The ratio had insignificant effect on proton conductivity of the composite membranes. Reducing alcohol ratio from five to three, however, led to 80% chemical resistance reduction and 70% higher methanol permeability. Finally, these composite membranes with five volume ratio of alcohol were used in membrane electrode assembly and tested in a DMFC compared to recast Nafion membrane. The composite membranes gave a maximum power density of 11.5 mW·cm-2 at 343.15 K, which was 58% higher than that of recast membrane.