Hybrid Hydrotalcite−Sulfonated Poly(ether ether ketone) Cation-Exchange Membranes Prepared by in situ Sulfonation

Abstract

Direct methanol fuel cells (DMFC), which operate using methanol as a fuel, are attracting considerable attention recently. However, DMFC face a major technical hurdle, namely, methanol crossover through the polymer electrolyte membrane. For example, the commercial Nafion membranes, in addition to being expensive, also often allow more than 40% of the methanol to be lost through crossover during fuel cell operation. Our study’s goal, therefore, was to develop a new, cost-effective membrane with superior methanol barrier properties to Nafion but which also maintains reasonable proton conductivity. We have prepared membranes by in situ sulfonation of hybrid poly(ether ether ketone) (PEEK) and hydrotalcite (HT) films. These composite HT−SPEEK polymer membranes show high conductivity and low methanol diffusivity and are comparable in their performance with commercial Nafion membranes. Their properties depend strongly on the sulfonation reaction time and the fraction of hydrotalcite contained in the original po...