Suppression of methanol cross-over in novel composite membranes for direct methanol fuel cells

A series of novel composite membranes was prepared by using poly(vinyl alcohol) (PVA) with polyimide (PI) as base material and 8-trimethoxysilylpropyl glycerine ether-1,3,6-pyrenetrisulfonic acid (TSGEPS) as proton conductor for direct methanol fuel cells (DMFCs). The parameters of membranes, including water sorption, hydrolysis stability, dimensional stability, proton conductivity, and methanol permeability were studied. The proton conductivity of the membranes is in the order of 10 –2 S/cm, and the membranes show better resistance to methanol permeability (1.51 × 10 –7 cm 2 s –1 ) and better selectivity (20.6 × 10 4 S cm –3 s) than those of Nafion115 under the same measurement conditions.