Highly Conductive and Dimensionally Stable Anion Exchange Membranes Based on Poly(dimethoxybenzene-co-methyl 4-formylbenzoate) Ionomers

The chemical stability of anion exchange membranes (AEMs) greatly affects their practical applications in alkaline membrane fuel cells. Here, highly conductive and dimensionally stable AEMs based on a copolymer with a triphenylmethane backbone (without aryl ether linkages) were prepared via Friedel–Crafts polycondensation. The as-prepared AEMs showed a high hydroxide conductivity (124.2 mS cm–1 at 80 °C) and good alkaline stability in 2 M KOH solution at 60 °C. Furthermore, the AEMs with high ion exchange capacity (IEC: 2.17 mmol g–1) displayed high mechanical properties and good dimensional stability. The single H2/O2 fuel cell utilizing the PDMB-Pi-0.7 membrane showed a maximum power density of 212.8 mW cm–2 at a current density of 425.5 mA cm–2 at 60 °C. This study provides a general synthesis strategy for the preparation of stable AEMs with high hydroxide ion conductivity and good dimensional stability for alkaline membrane fuel cells.