Chemo-stable poly(quinquephenylene-co-diphenylene piperidinium) ionomers for anion exchange membrane fuel cells

Anion exchange membrane (AEM) is a key component of polyelectrolyte electrochemical devices that operates under alkaline conditions. AEMs that can endure in harsh caustic and oxidative environments while exhibiting mechanical robustness and high ion conductivities are highly desired. In this study, we present a series of poly(quinquephenylene-co-diphenylene piperidinium) (PQDP) AEMs that have excellent alkaline and oxidative stabilities. Specifically, this membrane can retain its conductivity after 30 days aging in 1 M NaOH solution at 80 °C as well as over 95% of the initial mass after treatment in Fenton's reagent at 80 °C for 5 h. Moreover, the excellent mechanical properties (Young's modulus ~ 1 GPa, tensile strength > 40 MPa) are also observed for PQDP membranes. The heteroatom linkage-free backbone as well as the high contents of arylene units are responsible for the chemically and mechanically stable PQDP membranes. A PQDP membrane with the highest IEC (PQDP-3, 2.44 mmol g−1) demonstrate a high anion conductivity in Cl− form (73 mS cm−1 at 90 °C). Based on the high performance of PQDP membranes, a fuel cell prototype using PQDP-3 shows a high peak power density of 507 mW cm−2 at 80 °C with a current density of 0.97 A cm−2.