| Direct methanol fuel cells (DMFCs) have attracted considerable attention as an alternative to the present power sources, since they offer numerous benefits. However, at present, two major technology problems in DMFC still restrict their performance and applications. One problem is the crossover of methanol through the electrolyte membrane. The other is slow methanol oxidation kinetics on the anode catalyst. In this study, the membranes with high quality of proton conduction, thermal stability, and low methanol permeability were investigated.Based on the two groups of polymers, polyvinyl alcohol (PVA) and sulfonated poly(ether ether ketone) (SPEEK), several kinds of well-chosen-inorganic compounds, such as phosphotungstic acid (PWA), nano-alumina and 3A-molecular sieve (3A-MS) were mixed into the polymers. A series of inorganic-orgainc composite proton exchange membanes were prepared successfully. And the effects of the inorganic components on the composite membranes were studied.PWA are known to be one of the best inorganic proton conductors at room temperature. PWA doped PVA membranes with the highest conductivity of 22.0× 10-4S/cm-1 were prepared. The polyfunctioned PVA by oxalic acid showed good proton conductivity of 5.31 ×10-3S/cm-1, and its methanol permeability is 2.5× 10-7cm2/s-1 which is much lower than Nafion membrane whose methanol permeability is 13.0 × 10-7cm2/s-1 H2SO4 doped PVA membranes have much higher proton conductivity with the maximum value of 0.24S/cm-1SPEEK membranes with controlled degree of sulfonation (DS) were prepared and their feasibility for DMFC applications was studied. The influence of solvents of SPEEK membranes on their proton conductivity was studied. SPEEK-PWA-3A composite membrane didn't show improvement on proton conductivity, for 3A molecular sieve didn't cooperate with SPEEK. However, the nano-alumina and the active Bentonite intercalated by DMSO improved proton conductivity of SPEEK membranes.
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