Anion exchange membranes composed of poly(m-terphenylene)s and pendant ammonium head groups for anion exchange membrane water electrolyzers

Abstract

The development of high-performance anion exchange membranes (AEMs) is essential for advancing alkaline water electrolysis technology. Achieving a balance between ionic conductivity, chemical stability, and long-term durability under harsh alkaline conditions is critical for optimizing membrane performance. In this work, we designed AEMs featuring meta-kinked terphenylene in the backbone and hexyl spacer-tethered ammonium head groups to enhance both ion conductivity and chemical stability. The synthesized membranes demonstrated a high ionic conductivity, up to 144 mS cm -1 at 80 o C. Long-term ex-situ stability testing in 8 M KOH at 80 o C revealed that the membranes retained over 43% of their initial conductivity after 1,000 hours, with the mT-QAF-2.50 membrane retaining 54%. An AEM water electrolyzer (AEMWE) single cell using an mT-QAF-2.50 membrane delivered outstanding electrochemical performance with a cell voltage of 1.58 V (94% voltage efficiency) at a current density of 1.0 A cm -2 . The cell maintained stable performance, with a minimal voltage decay of 2.4 µV h -1 from 100 to 1,000 hours at 1.0 A cm -2 at 80 o C, highlighting the membrane's exceptional durability.This study showcases the potential of terphenyl-based AEMs with ammonium cations as a promising material for high-performance, durable, and efficient applications in alkaline water electrolysis, advancing the development of next-generation hydrogen production technologies.