Dimensionally stable multication-crosslinked poly(arylene piperidinium) membranes for water electrolysis

Cross-linking is a widely employed process to improve the dimensional stability of anion exchange membranes (AEMs). However, crosslinking often comes at the expense of ion exchange capacity and ionic conductivity. To address this “trade-off” problem, we introduce a multication crosslinker composed of two piperidinium groups and a flexible alkyl chain to fabricate novel crosslinked poly(arylene piperidinium)-based AEMs (C-IL-x). It is found that multication crosslinkers can promote the fabrication of micro-phase separated morphology and construct highly efficient ion conducting pathways inside the membrane. Compared to the non-crosslinked AEM, the conductivity and dimensional stability of crosslinked C-IL-x AEMs were improved simultaneously. The highest ionic conductivity of the crosslinked C-IL-x AEMs reaches up to 95 mS cm−2 at 80 °C. In addition, alkaline water electrolysis using the C-IL-100 AEM (100 refers to the expected crosslinking degree) exhibits a high current density of 880 mA cm−2 at 2.2 V in 1 M KOH solution with Ni-based catalysts, which confirms that multication crosslinked AEMs are promising for application in alkaline water electrolysis.