Improving performance of poly(carbazole)-based anion exchange membrane for fuel cells by reinforced cation-dipole interaction

To develop the anion exchange membranes (AEMs) with enhanced alkaline stability and superior performance, a series of high-density hydrophilic segment poly(carbazole)-based AEMs (designated as PBOMC-R) incorporating cation-dipole interaction were synthesized via step-feeding polymerization in this work. Among them, the comparison of different cationic groups in cation-dipole interaction for properties of the AEMs were emphatically discussed. The results indicated that the PBOMC-R (IEC = 1.90–2.19 mequiv. g −1 ) possessed appropriate water uptake and excellent dimensional stability. Theoretical simulations revealed that the cation-dipole interaction resulted from different cation type varied with an order TMA > PYR > DMI > PIP, and a reinforced cation-dipole interaction could be obtained through choosing a proper cationic group. While a stronger interaction force could more readily gather cationic groups to form a larger hydrophilic region for ion transport, which is consistent with the rule of microscopic morphology. Thus, the AEM PBOMC-TMA with the most potent cation-dipole interaction displayed the highest ionic conductivity, reaching 188.2 mS cm −1 at 80 °C. After the alkaline aging test (2 M NaOH, 80 °C, 1080 h), the membranes retained 85.1–95.1 % ionic conductivity, validating exceptional alkaline durability. Fuel cell tests demonstrated that PBOMC-TMA attains 779 mW cm −2 peak power density and a sustained 100 h operation at 0.03 mV h −1 voltage decay rate, thereby suggesting significant technological potential for alkaline fuel cell applications.