Highly conductive anion exchange membranes with long flexible multication spacer

Abstract

Poly(ether ketone)s bearing multication side chains are synthesized via nucleophilic polycondensation, demethylation and the Williamson reaction to prepare high performance anion exchange membranes (AEMs). The introduction of multication side chains is found to promote the formation of hydrophilic/hydrophobic phase segregated morphology, as confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The TQAPEK-0.5 membrane with ionic exchange capacity (IEC) of 1.94 meq g−1 shows the highest hydroxide conductivity of 132.8 mS cm−1 at 80 °C. The first cationic group on the side chain is linked to the backbone via hexyleneoxy groups to render the AEM a good alkaline stability. As a result, TQAPEK-0.5 has only a 22.4% decrease in the conductivity after immersed in a 2 M aqueous KOH solution at 60 °C for 600 h. Besides, the peak power density of a single cell using the TQAPEK-0.5 membrane is observed to be 206 mW cm−2 at a current density of 400 mA cm−2. Furthermore, the as-prepared AEMs also exhibit good mechanical property and thermal stability, and hold promise for application in fuel cells.