Electrochemical Behavior of Direct Methanol Fuel Cells based on acidic Silica - Sulfonated Polysulfone Composite Membranes

This paper reports on the research and development of polymer electrolyte membranes based on sulfonated polysulfone and acidic silica materials for application in DMFCs at different operating temperatures. The sulfonated polysulfone (SPSf) was synthesized using trimethyl silyl chlorosulfonate as the sulfonating agent, whereas silica was modified by treatment with chlorosulfonic acid at room temperature. The composite membranes based on sulfonated polysulfone and acidic silica were prepared by using a casting method from dimethylacetamide solutions. The membranes were characterized in terms of ion exchange capacity, methanol/water uptake, proton conductivity and DMFC performance. The membrane containing 10 wt.% of acidic silica showed a promising performance in DMFC investigations at temperatures comprised between 30 degrees C and 60 degrees C. A maximum power density of 60 mW cm(-2) was obtained at 60 degrees C feeding 1M methanol solution at the anode and dry air at the cathode, both at atmospheric pressure.