Abstract: New proton exchange membranes of sulfonated poly(ether ether ketone)(SPEEK) and sulfonated phenolphthalein poly(ether sulfone)(SPES-C) were prepared and their proton conductivity and methanol permeability were investigated. The new membranes show a high proton conductivity, which is close to that of Nafion especially at high temperature. Methanol permeability of the new membranes is 1～2 order lower than that of Nafion and the SPEEK membrane has the lowest methanol permeability. Direct methanol fuel cell (DMFC) performances of the new PEMs were also studied and the result demonstrates that the membranes with low methanol permeability show a high open circuit voltage. However, the performance of the DMFC is mainly controlled by the proton conductivity of the membranes at high current density.

Key words: Direct methanol fuel cell(DMFC), Proton exchange membrane, Membrane electrode assemble (MEA), Proton conductivity, Methanol permeability