Hydrogen‐Bonding Enhanced Anion Exchange Membrane for High Performance Alkaline Water Electrolysis

Abstract

Anion exchange membranes (AEMs) are critical for alkaline water electrolysis but face challenges related to low hydroxide ion (OH−) conductivity and poor chemical stability. Herein, an AEM design strategy is presented that integrates frontier molecular orbital engineering with hydrogen‐bonding network construction. HOMO energy level as a descriptor is first introduced to evaluate oxidative stability of AEMs, particularly their backbones, while LUMO energy level is used to evaluate alkaline stability of cation groups. Density functional theory (DFT) calculations show that benzothiazole (BT) features a high LUMO energy and low HOMO energy level, suggesting good stability. Incorporating BT into poly(terphenyl‐benzothiazole‐piperidinium) membrane (P‐B‐x) enables the formation of enhanced continuous hydrogen‐bonding networks, where BT's nitrogen and sulfur heteroatoms act as dual hydrogen‐bonding acceptors, facilitating OH− transport of Grotthuss‐type. The optimized P‐B‐15 membrane with a moderate ion exchange capacity achieves the high OH− conductivity of 168.7 ± 1.0 mS cm−1 at 80 °C and sustains stable operation for over 500 h at 1.0 A cm−2 with minimal voltage decay (32 µV h−1) in 1.0 m KOH. This work proposes a promising strategy for the development of next‐generation AEMs with enhanced OH− conductivity and chemical stability.