A review on transport properties and performance of commercial and novel membranes for anion exchange membrane water electrolyser

Abstract

The growing demand for renewable-powered hydrogen drives interest in water electrolysis, making anion exchange membrane water electrolysis (AEMWE) an emerging technology. The anion exchange membrane (AEM) integrates the benefits of both the proton exchange membrane (PEMs) and alkaline water electrolysis (AWEs), enabling the use of cost-efficient transition metal catalysts instead of precious metals and operating in distilled water or low-concentration KOH electrolytes, thereby reducing corrosion issues. Like PEMWE, AEMWE offers high-purity hydrogen, broader material compatibility, and reduced system costs. Moreover, it offers a low-temperature alternative to solid oxide electrolysis (SOECs), simplifying system integration. Despite these benefits, large-scale adoption is limited by several challenges, including limited alkaline stability of membranes, trade-offs between ionic conductivity and durability, insufficient long-term stability of PGM-free catalysts, and elevated interfacial resistance at membrane electrode assembly (MEA) and porous transfer layer (PTL) junctions. These constraints are reflected in conventional AEMs, which typically exhibit limited conductivities of ∼100 mS/cm at 60–80 °C with lifetimes of under 1000 h. In contrast, commercial membranes demonstrate higher conductivities of ∼150 mS/cm, enabling improved performance, delivering current densities of 0.8–1.2 A/cm2 at voltages of 1.8–2.0 V. Recent developments in novel AEMs have further enhanced both current density and stability by 20–30 %, achieving >1.6 A/cm2 and >1500 h under optimised conditions. However, the long-term durability of PGM-free catalysts remains a critical limitation. In addition to technical performance, AEMWE also presents economic advantages over other electrolysis technologies. This review systematically evaluates commercial membranes, including Tokuyama, Fumatech, Orion, Aemion, Sustainion, and Piperion, alongside emerging alternatives. Key aspects such as chemical structures, ion transport properties, electrochemical performance, cost analysis of commercial membranes, degradation mechanisms, and advances in MEAs are examined. The role of PGM and PGM-free catalysts in improving efficiency and reducing costs is also highlighted. Several novel membranes demonstrate performance comparable to or exceeding commercial standards, indicating strong potential for future commercialisation. Finally, the review identifies critical research gaps, including the need for alkaline-stable polymers, durable PGM-free catalysts, optimised MEA/PTL architectures to mitigate interfacial resistance, and standardised long-term testing protocols, which are essential for transitioning AEMWE from laboratory studies to scalable, cost-effective hydrogen production systems. © 2025 Hydrogen Energy Publications LLC