Development of low cross-over composite membrane composed of porous polyimide and polymer electrolyte for direct methanol fuel cells

摘要

Three kinds of proton conducting composite electrolyte membranes with three-dimensionally ordered macroporous (3DOM) polyimide were fabricated. Their performances for direct methanol fuel cells were compared. Poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS), sulfonated poly (1,4-phenylene ether ether sulfone) (SPEES), and sulfonated poly (1,4-phenilene ether ether ketone) (SPEEK) were employed as filling electrolytes. No swelling was observed in any composite membrane. The highest proton conductivity of 7.4 × 10~(-2) S cm~(-1) was obtained for composite membrane with PAMPS having the highest ion exchange capacity. On the other hand, the lowest methanol permeability of 1.3 × 10~(-8) cm~2 s~(-1) was obtained for composite membrane with SPEEK having the lowest water uptake. The contribution of 3D0M polyimide to the methanol permeability was larger than to the proton conductivity. Thus, nearly two orders of magnitude larger proton transfer selectivity of 1.1 × 10~6 S cm~3 s~(-1) compared to Nafion~® membrane was obtained in the SPEEK composite membrane.