Imidazole-Functionalized Multiquaternary Side-Chain Polyethersulfone Anion-Exchange Membrane for Fuel Cell Applications

A series of rPES­(x/y)-MI membranes with different rigid side chains and high-density imidazole cationic groups have been prepared for anion-exchange membrane (AEM) fuel cells (AEMFC). These AEM rPES­(x/y)-MIs with IEC values of 1.91–2.31 mequiv g^–1 exhibit high conductivities of 92.92–142.69 mS cm^–1 at 80 °C, acceptable water uptake, and dimensional change. Density functional theory (DFT) was used to demonstrate the excellent alkali stability of this class of copolymers, which is consistent with experimental results. In addition, the degradation mechanism of this type of AEM has also been investigated. Significantly, rPES­(1/4)-MI-based AEMFC has the maximum power density of 195 mW cm^–2 at a current density of 525 mA cm^–2, which is much higher than commercial reference membrane FAS-30 measured in the same environment.