Primary study on double-layer membranes for direct methanol fuel cell

The double-layer membranes consisting of sulfonated poly(ether ether ketone) (SPEEK) sub-layer and polyvinyl alcohol (PVA) sub-layer were investigated for direct methanol fuel cell (DMFC). The membranes with different prescriptions were prepared by two-step solvent casting. Swelling behavior in water and 2 M methanol solution, ion exchange capacity (IEC) and methanol permeability of the membranes were studied and discussed. In 2 M methanol solution, SP63 provided the planar swelling ratio of 8.16 % and zero at 80 °C and 25 °C, respectively. The low swelling behaviors in planar direction are expected to be useful in maintaining the tight contact between electrolyte membrane and catalyst layer. The double-layer membranes were assembled in DMFC, PVA sub-layer adhered to anode to block methanol crossover. Proton conductivities of the double-layer membranes are restricted by the lower conductivity of PVA sub-layer, which would be improved in our further research. The double-layer membranes are suggested to be ideal candidate proton exchange membrane for DMFC application.