Radiation-grafted anion-exchange membranes

Abstract

Tailored, radiation-induced grafted anion-exchange membranes (RIG-AEMs) are incorporated in anion-exchange membrane water electrolyzers. Fabrication parameters of the polymeric electrolyte directly impact the performance of electrochemical devices. The effect of radiation absorbed dose, polymer type (low-density polyethylene (LDPE) or ethylene-tetrafluoroethylene (ETFE)), and polymer film thickness on current-voltage characteristics is studied. The radiation absorbed doses and the polymer thickness influence the degree of grafting (DoG) and ion-exchange capacity (IEC) of the synthesized membranes, which are correlated to their ionic conductivity and dimensional stability. The in operando electrochemical characterization in single cell electrolyzers, utilizing stainless steel felt as a combined anode catalyst and porous transport layer, required voltages as low as 1.78 V at 1 A cm−2 in 1 M KOHaq at 60 °C. LDPE-based RIG-AEMs were found more durable than ETFE-based RIG-AEMs over a 100 h period at a constant current density of 0.5 A cm−2 (voltage increase of 71 μV h−1 for L-50-30 AEM vs. 300 μV h−1 for E-25-20 AEM). These results provide valuable insights into the tradeoff between performance and durability of AEM water electrolyzers to guide the development of RIG-AEMs for water electrolysis applications.