Alkyl Imidazolium Cation-Supported Poly(terphenyl- co -fluorene isatin) Anion Exchange Membrane for Anion Exchange Membrane Fuel Cells

Abstract Anion exchange membrane (AEM) is the core component of alkaline fuel cells. Current research still faces bottlenecks such as the difficulty in synergizing ion conductivity and alkali stability, and the inhibition of reaction kinetics by adsorption of ionomer catalysts. In this work, a new ether-free poly(terphenyl-co-fluorene isatin) polymer backbone was developed. Alkyl imidazole with a unique π-conjugated delocalized structure was selected as a cation to develop a series of imidazole cation-loaded comb-shaped poly(terphenyl-co-fluorene isatin) polyelectrolytes (PTFI-IZ-n). The additional hydrophobic structure on the imidazole cation provides a driving force for the self-assembly of ion clusters. PTFI-IZ-8 AEM exhibits the most developed phase separation morphology and exhibits a high OH– conductivity of 140.61 mS/cm at 80 °C. The long comb-like alkyl chain in PTFI-IZ-8 AEM effectively protects the stability of the cation. After 1200 h in 2 M NaOH at 80 °C, the ion conductivity only decreased by 10.32% and the tensile strength decreased by 11.05%. The peak power density of H2–O2 AEMFC based on PTFI-IZ-8 can reach 1.03 W/cm2 at 80 °C, providing a new strategy for the design of high-performance anion exchange membranes.