Crosslinked polynorbornene-based anion exchange membranes with regionally intensive ion clusters: Effect of the polymer backbones

Abstract

The anion exchange membranes (AEMs) serving as the pivotal component exert crucial influences on anion exchange membrane fuel cells (AEMFCs). However, the “trade-off” between conductivity, dimensional stability, and alkaline stability of AEMs remains a formidable challenge. Herein, a series of crosslinked polynorbornene-based AEMs with regional intensive ion clusters were prepared through the introduction of 1,3,5-tris [3-(dimethylamino)propyl] hexahydro-1,3,5-triazine (PHT). The rational molecular structure design that combines all-carbon hydrogen block copolymer backbones, long flexible alkoxy spacers and cationic cluster crosslinking structures contributed to regulation of the functional cation content, ion transport channels and the stability of the AEMs. It was found that the prepared AEMs exhibited the anticipated characteristics of superior hydroxide conductivity (145.3 mS cm⁻¹) and low swelling ratio (SR ≤ 18.27 %) at 80 °C. Furthermore, after treatment in 1 M NaOH solution at 80 °C for 960 h, the hydroxide conductivity of AEMs was maintained at 80.52–88.93 % of the original conductivity, indicating that these membranes possess excellent alkaline stability. In addition, the peak power density of H₂/O₂ fuel cell equipped with aPNB-PHT-QA-1.93 and rPNB-PHT-QA-1.89 achieved 317.6 mW cm⁻² and 245.3 mW cm⁻² at 80 °C, respectively. This work provides an effective approach to prepare high-performance AEMs and shows potential application in fuel cells.