Synergistic effect and ionic conductivity of crosslinked imidazole ionic liquids and piperidine cations on poly(biphenyl-piperidine) anion exchange membranes

Abstract

In order to prepare anion exchange membranes with good performance, and we prepared ether-free bonded poly(biphenyl-piperidine) anion exchange membranes (CQPBP-M-x, x is degree of crosslinking) by introducing cross-linked imidazolium ionic liquids. The introduction of cross-linked imidazolium ionic liquids increases multiple OH− transport sites and establishes a more pronounced microphase-separated structure with the backbone, while acting synergistically with piperidinium cations, resulting in improved membrane conductivity. Meanwhile, the introduction of an ether-free backbone and the construction of a cross-linked structure could promote the chemical stability of the membrane and effectively inhibit membrane swelling. The prepared cross-linked imidazole ionic liquid poly(biphenyl-piperidine) (CQPBP-M-30 %) membrane exhibited relatively good ionic conductivity (88.03 mS/cm), and low swelling (11.75 %) at 80 °C. The H2–O2 fuel cell performance test conducted at 80 °C without back pressure showed a peak power density of 125.7 mW/cm2. Therefore, it is a worthwhile direction to explore to improve the performance of anion exchange membranes by adopting an ether-free backbone and constructing a cross-linked structure contain multiple cationic groups.