Preparation and Characterization of Composite Membrane for Low Temperature Direct Methanol Fuel Cells

Preparation and Characterization of Composite Membrane for Low Temperature Direct Methanol Fuel Cells

A series of H₃PO₄-doped composite membranes based on poly(vinyl alcohol)(PVA) and silica have been prepared by sol-gel process. The proton conductivity, as well as properties of swelling, methanol permeation, was measured in this study. The proton conductivity increased with the molar ratio of H₃PO₄ to silica. With the silica content increasing, swelling degree decreased and methanol permeability showed a slight increase. It suggested that the former was mainly determined by hydrophilicity of the membrane, while the latter was dominated by the interconnectivity of matrix. According to the value of on, the optimal conformations of these composite membranes were 60, 70, 80 wt.% of PS-x in membranes, where x were 1.5, 1.0, and 0.5, respectively. These composite membranes were thermal stability up to 200℃.