Block-branched poly(aryl piperidinium) anion exchange membrane for highly durable pure water electrolysis

Anion exchange membrane water electrolysis (AEMWE) has garnered significant attention due to its potential for low cost and high efficiency, with the anion exchange membrane (AEM) serving as its core component. However, the trade-off between stability and ionic conductivity remains a key challenge hindering the advancement of AEMs. In this work, we introduce a novel twisted multi-directional branching agent, hexaphenylbenzene (HPB), to poly(terphenyl piperidinium) (PTP) and employ a block-branching synthetic strategy. Specifically, the block poly(terphenyl-HBPB-piperidium) (B-PTHP) membrane achieved low swelling (14.2% at 80 °C) and high ionic conductivity (183.6 mS cm -1 at 80 °C), alongside excellent oxidative stability (retained 88.1% of its mass after 96 h in Fenton reagent) and alkaline stability (retaining 97.2% of OH - conductivity after 1500 h in 1 M KOH). Consequently, the B-PTHP membrane reached a current density of 1.06 A cm -2 at 2 V and running over 740 h at 0.25 A cm -2 in a pure-water-fed AEMWE. Meanwhile, it also achieved a current density of 8.26 A cm -2 at 2 V and stable operation for over 2500 h at 0.5 A cm -2 and 60 °C in a 1 M KOH-fed AEMWE. Therefore, our work contributes to addressing the critical challenges of oxidative stability and pure-water-fed AEMWE.