ETFE-grafting ionomers for anion exchange membrane water electrolyzers with a current density of 11.2 A cm−2

Abstract

In the quest for efficient and sustainable hydrogen production, anion exchange membrane (AEM) water electrolyzers (AEMWEs) have gained significant attention. Development of AEMs has accelerated in the past few decades while the significance of the ionomer on AEMWE performance and durability is always unrecognized. In this study, we proposed a class of electrochemically durable ionomers by introducing the piperidinium group onto the ethylene tetrafluoroethylene (ETFE) backbone using a radiation grafting technology. To avoid disruption of the conformation of the piperidinium group during the functionalization process, we grafted the piperidinium group onto the polymer backbone at the gamma position of the N-piperidinium group using trifluoromethanesulfonic acid as a catalyst. The prepared ETFE-g-poly(styryl propyl piperidinium) ionomers exhibited outstanding electrochemical properties and enhanced alkaline stability. Most notably, the corresponding AEMWEs demonstrated an impressive current density of 11.2 A cm−2 at 2.0 V under 80 °C in 1 M KOH solution. Furthermore, they were continuously operated at a current density of 0.5 A cm−2 for over 300 h with a low voltage decay rate of 0.12 mV h−1. This study offers valuable insights into the development of robust solid-state ionomers through radiation grafting, paving the way for high-performance AEMWEs.