Tuning catalyst layer swelling via crown ether ionomers for stable alkaline water electrolysis

Anion exchange membrane water electrolysis (AEMWE), based on the membrane electrode assembly (MEA) structure, is a highly viable technology for hydrogen generation. However, systematic research on the effects of ionomer structure and content on electrolysis performance remain limited. Hence, a series of previously studied PDTP-x polymers and a control copolymer PDTP-30-15 (where 15 denotes the molar content of 2,2,2-trifluoroacetone (TFAp) monomer) were investigated as binders in the cathode catalytic layer for AEMWE. By optimizing the balance between water uptake/swelling ratio and electrochemical performance, the MEA based on PDTP-20-20 % ionomer achieved a current density of 2000 mA/cm 2 at 2.1 V during operation with 1 M KOH at 80 °C. For AEMWE durability, the MEA employing PDTP-30-15 ionomer exhibited superior stability, with the cell voltage increasing only from 1.68 V to 1.76 V over 110 h (decay rate: 0.73 mV/h) and a 30 % rise in high-frequency resistance (HFR). The enhanced performance of PDTP-30-15 over PDTP-20 is attributed to its exceptional alkaline stability and lower water uptake. Therefore, developing ionomer materials with minimal dimensional variation and high chemical stability constitutes a pivotal future research direction for AEMWE. • Crown ether ionomers were evaluated as binders for AEMWEs. • Binders with balanced SR and electrochemical properties boost AEMWE performance. • The PDTP-30-15-based cathode CL showed outstanding AEMWE durability.