Durable Multiblock Poly(biphenyl alkylene) Anion Exchange Membranes with Microphase Separation for Hydrogen Energy Conversion

Abstract Anion exchange membrane fuel cells (AEMFCs) and water electrolysis (AEMWE) show great application potential in the field of hydrogen energy conversion technology. However, scalable anion exchange membranes (AEMs) with desirable properties are still lacking, which greatly hampers the commercialization of this technology. Herein, we propose a series of novel multiblock AEMs based on ether‐free poly(biphenyl ammonium‐b‐biphenyl phenyl)s (PBPA‐b‐BPPs) that are suitable for use in high performance AEMFC and AEMWE systems because of their well‐formed microphase separation structures. The developed AEMs achieved outstanding OH − conductivity (162.2 mS cm −1 at 80 °C) with a low swelling ratio, good alkaline stability, and excellent mechanical durability (tensile strength >31 MPa and elongation at break >147 % after treatment in 2 M NaOH at 80 °C for 3750 h). A PBPA‐b‐BPP‐based AEMFC demonstrated a remarkable peak power density of 2.41 W cm −2 and in situ durability for 330 h under 0.6 A cm −2 at 70 °C. An AEMWE device showed a promising performance (6.25 A cm −2 at 2 V, 80 °C) and outstanding in situ durability for 3250 h with a low voltage decay rate (<28 μV h −1 ). The newly developed PBPA‐b‐BPP AEMs thus show great application prospects for energy conversion devices.