Macromolecular crosslinked poly(aryl piperidinium)-based anion exchange membranes with enhanced ion conduction for water electrolysis

Anion exchange membranes (AEMs) are essential in AEM water electrolysis, providing a cost-effective alternative to proton exchange membranes through the use of noble metal-free electrocatalysts. However, the "trade-off" between conductivity and dimensional stability in AEMs still hinders the development of high-performance water electrolysis. Herein, partially functionalized poly(phenylene oxide) (QPPO) is combined with poly(aryl piperidinium) (QPAP) to fabricate novel crosslinked AEMs (C-QPAP-x-QPPO), addressing the conductivity-stability issue. The crosslinked C-QPAP-x-QPPO AEMs show lower water swelling compared to their non-crosslinked QPAP membrane, mainly due to increased chain entanglements from the crosslinking process. C-QPAP-2-QPPO AEM exhibits a high conductivity of 139.4 mS cm−1 at 80 °C, attributed to the well-defined microphase separation structure. In addition, C-QPAP-2-QPPO AEM demonstrates exceptional alkaline durability, retaining over 86% conductivity and showing slight degradation after 2400 h in 1 M KOH at 60 °C. A water electrolyzer using the C-QPAP-2-QPPO achieves a maximum current density of 1440 mA cm−2 at 80 °C (2.0 V). These findings demonstrate the potential applications of crosslinked C-QPAP-x-QPPO AEMs in electrochemical devices.