Towards high conductivity and stability diblock poly(norbornene)s-based anion exchange membranes crosslinked with alkyl quaternary ammonium cationic clusters

Anion exchange membranes (AEMs) with exceptional comprehensive performance, combining high conductivity, alkaline and dimensional stability, have been indispensable for the practical application in fuel cells. Herein, a robust addition poly(norbornene)s-based AEMs with an all-carbon-hydrogen bicyclic skeleton were fabricated by cross-linking of alkyl quaternary ammonium cationic clusters and further quaternization. The partially crosslinked AEMs adopt a synergistic strategy that combines diblock copolymer backbone, cationic cluster crosslinking structure, and long flexible spacer suspended with cationic head groups. Benefiting from these structural design advantages, the prepared AEMs possessed excellent hydroxide conductivity (133.9-146.9 mS cm-1) and low swelling ratio (SR <= 20%) at 80 degrees C. The robust crosslinked AEMs exhibited good mechanical properties and high thermostability, with onset of decomposition temperatures up to 240 degrees C. Furthermore, after 44 days treatment in 1 M NaOH solution at 80 degrees C, the hydroxide conductivity of AEMs maintained at 79.4-85.7% of the initial value depending on the crosslinking degree, demonstrating excellent alkaline stability. In addition, the H2/ O2 single cell equipped with CL20-aPNB-TAT-QA-1.75 achieved a peak power density of 338.0 mW cm-2 at 80 degrees C. The study provided a meaningful insight to exploit the practical application of multi-cation clusters crosslinked addition poly(norbornene)s-based AEMs in fuel cells.