Polymer-ceramic proton exchange membranes for direct methanol fuel cells

Abstract

Proton-exchange composite membranes based on poly(vinyl alcohol)/BEA zeolite for direct methanol fuel cell were obtained. Poly(vinyl alcohol) was crosslinked with sulfosuccinic acid and doped with BEA zeolite. Proton conductivity, ion-exchange capacity, water uptake, swelling ratio, methanol permeability and mechanical properties of membranes were tested. An increase in the zeolite content leads to an increase in ion-exchange capacity and a decrease in water uptake and methanol permeability of membranes. The proton conductivity temperature dependence of composite membranes in the range from 30 to 80 °C and a 100% of relative humidity was studied. The best result was demonstrated by the membrane containing 25% BEA (proton conductivity −23.2 mS cm−1, the activation energy −26 kJ mol−1 K−1). The tensile strength increases with the addition of zeolite in 4 times, and the elongation at break decreases in more than 5 times (25% BEA sample) as compared to the membrane without additives.