Large electronegative hydrophobic side chain modified high conductive and stable polycarbazolyl anion exchange membrane for fuel cell application

As a core component of anion exchange membrane fuel cells (AEMFCs), the anion exchange membrane (AEM) has been severely affected by the “trade-off” effect between ionic conductivity and dimensional stability, as well as poor alkaline stability, which seriously limits the development of its commercialization. In this study, a novel polycarbazolyl AEM with large electronegative hydrophobic side chain (QPBC-HPO) was designed and prepared. The results demonstrated that the AEM QPBC-HPO showed a higher ionic conductivity of 156.8 mS cm −1 than that of the reference AEMs, which is attributed to the orientation of cationic groups driven by the large electronegative side chain, while this is conducive to the formation of a regular continuous ion transport channel in the membrane, supported by micromorphology characterization and theoretical calculation of molecular model. Additionally, the hydrophobic side chain contributed to proper water uptake and high dimensional stability in the AEM QPBC-HPO, mitigating the “trade-off” effect. Furthermore, the AEM QPBC-HPO exhibited higher alkaline stability with 85.5 % ionic conductivity retention after prolonged aging in 2 M NaOH solution at 80 °C for 1080 h. Fuel cell performance testing demonstrated a maximum power density of 532 mW cm −2 for the AEM QPBC-HPO with 100/200 mL min −1 of H 2 /O 2 flow and 100 % RH at 60 °C, while cell in-situ durability assessment at 100 mA cm −1 of constant current revealed a minimal voltage drop rate of only 0.12 mV h −1 after 72 h of operation, highlighting its promising potential in AEMFC.