Processing of proton exchange membrane for direct methanol fuel cell

Abstract

Proton exchange membrane (PEM) is a polymeric electrolyte to be applied in direct methanol fuel cells (DMFC). The membrane supports proton transport and divides fuel of cathode and anode. Nafion is widely used as the membrane in DMFC because of its high proton conductivity and mechanical strength. Nevertheless, it is high methanol permeability and very expensive. The high methanol permeability leads to a decrease in DMFC performance. Therefore, alternate polymer membranes were developed. Polysulfone and polyvinylidene fluoride were used as PEMs in this work. The polymer membranes were characterized for the degree of sulfonation, ion exchange capacity, proton conductivity, water uptake, and mechanical strength. The degree of sulfonation was improved with increasing ratio of acid per polymer and affected both proton conductivity and water uptake. The properties of membranes were directly compared with a commercial membrane Nafion.