A novel anion exchange membrane comprised of three aromatic units for fuel cells

Anion exchange membrane fuel cell (AEMFC) has made great progress recently due to the continuous improvement of anion exchange membrane (AEM). Aryl ether bond-free membranes are considered to be promising for improving the overall performance of AEMs. Here, we present a copolymer consisting of m-terphenyl, diphenyl ethane and biphenyl (PMDBP) to further enhance the microphase separation structure by introducing a third structural unit, biphenyl. Meanwhile, the more compact biphenyl structure enhances the mechanical strength of AEMs. Specifically, PMDBP AEMs possess superior OH^- conductivity (up to 113 mS cm⁻¹) and excellent mechanical properties (tensile strength up to 42 MPa). Furthermore, the PMDBP has an outstanding single-cell performance with a peak power density (PPD) of up to 95 mW cm⁻² with a platinum-carbon (Pt/C) catalyst at 80°C in H₂-air. In addition, PMDBP is provided with excellent durability, including NMR spectral consistency and over 90% ion conductivity retention in 1 M NaOH at 60°C for 720 h. This study provided a copolymer structure suitable for anion exchange membrane that can provide excellent performance for fuel cells and electrolyzers.