Reinforced composite anion exchange membranes with aligned ion transport pathways for enhanced alkaline water electrolysis

Anion exchange membrane water electrolysis (AEMWE) is emerging as a next-generation technology for hydrogen production due to its cost-effectiveness and high efficiency. However, a key challenge remains for anion exchange membranes (AEMs), which suffer from limited mechanical stability when the temperature of the feed solution fluctuates. One potential solution involves reinforcing AEMs with robust inorganic fillers, though issues related to interfacial compatibility and ionic conductivity still persist. In this study, we address these challenges by incorporating rigid dual-functional Fe 3 O 4 nanoparticles into soft poly(styrene- b -(ethylene- co -butylene)- b -styrene) (SEBS) polymers under a magnetic field. The chemical crosslinking between the chloromethylated Fe 3 O 4 with chloromethylated SEBS improves interfacial compatibility, facilitating better dissipation of mechanical stress. Additionally, the in-situ formation of quaternary ammonium functional groups at the crosslinking points imparts anion-conducting capabilities to the Fe 3 O 4 . The magnetic response of Fe 3 O 4 further promotes microphase separation, leading to the formation and alignment of ion-transporting hydrophilic channels. As a result, the hybrid membranes achieve a OH − conductivity of 75.9 mS cm −1  at 80 °C and exhibit a swelling ratio of 5.6% at the same temperature, along with enhanced mechanical strength (>11 MPa under fully-hydrated conditions). Furthermore, in AEMWE single-cell tests, the membranes enable a current density of 1070 mA cm −2  at 2.0 V, corresponding to a 1.6-fold increase compared to quaternized SEBS. This novel structural design offers promising solutions for the development of high-performance polyelectrolyte conductive membranes, with broad applications in AEMWE and beyond.