Facilitating Rapid OH⁻/H₂O Transport in Anion Exchange Membranes via Ultra‐Stable Heteroatom‐Free Micropores

Abstract

Efficient OH^- conduction in anion exchange membranes (AEMs) is pivotal for the advancement and industrialization of sustainable electrochemical technologies in alkaline environments, including water electrolysis, fuel cells, and CO₂ electroreduction. We here designed AEMs with a novel class of rigid heteroatom-free micropores (HFMs), engineered at the molecular level to facilitate rapid ionic transport in an ultra-stable manner. By manipulating monomers, our design strategically controls the torsional angles and energy barriers within the polymeric backbones, creating sub-nanometer ionic channels that precisely regulate porosity. These hydrophilic micropores significantly enhance the mobility of OH^-/H₂O, achieving over a 150 % increase in self-diffusion coefficient compared to commercial AEMs and elevating OH^- conductivity to a leading 215 mS cm^-1 at 80 °C. Moreover, the robust carbon-carbon bond construction in HFMs offers the stability that is four orders of magnitude higher under severe alkaline conditions compared to existing wisdoms, with a demonstrated operational lifespan of over 4000 hours. The integration of HFM-AEMs into water electrolyzers not only supports the use of platinum group metal-free catalysts but also exhibits exceptional energy efficiency and extended durability, highlighting their substantial potential for wide-ranging applications in emerging electrochemical technologies.