Effect of branching degree of quaternized poly(p-terphenyl isatin) on the performance of anion exchange membrane water electrolyzers

Anion exchange membrane (AEM) is a vital component of an anion exchange membrane water electrolyser (AEMWE). Herein, we reported a series of quaternized poly(p-terphenyl isatin) (Q-PPI-bx) AEMs with the branching architecture and microporous structure by incorporating bulky rigid 1,3,5-triphenyl monomer through a superacid polycondensation reaction. It was found that the introduction of branching and microporous structures provided the membranes with a larger free volume and distinct microphase separation morphology, thus resulting in a higher OH− ionic conductivity (158.7 mS cm−1 at 80 °C). At the same time, the AEMs exhibited good mechanical properties and good alkaline stability (retention of 85 % for 1500 h in 1 M KOH at 80 °C). In addition, the current density of Q-PPI-b10 AEM was 1.14 A cm−2 at 2 V in AEMWE. During the in-situ endurance experiment at current density of 0.2 A cm−2, the voltage remained stable for 170 h. These findings underscore the potential of novel branched AEMs for application in AEMWE systems with enhanced performance and durability, thus contributing to the advancement of efficient and sustainable water electrolysis technology.