Controllable physical-crosslinking poly(arylene 6-azaspiro[5.5] undecanium) for long-lifetime anion exchange membrane applications

Abstract

Responding to the insufficient durability and mechanical stability of anion exchange membranes (AEMs) used in alkaline membrane fuel cells (AMFCs), a series of poly(biphenyl 6-azaspiro[5.5] undecanium) (PB-ASU) membranes were prepared by strong-acid condensation. For improving the comprehensive performance of the PB-ASU membrane, a profitably-crosslinked poly(biphenyl piperidinium) (PBP) segment was introduced to the PB-ASU backbone to fabricate a physical-crosslinked PB-ASU-PBP copolymer. The crosslinked PBP segment improves the dimensional stability and film-forming properties of PB-ASU-PBP membrane, but sacrifices a part of alkaline stability. As expected, all of the PB-ASU and PB-ASU-PBP membranes show superb alkaline stability, only tiny degradations of the PB-ASU (<6%) and PB-ASU-PBP (<9%) were detected by 1HNMR spectroscopy after alkaline treatment in 3 M NaOHaq at 80 °C for 2000 h. Besides, these PB-ASU-PBP membranes show good OH− conductivity of 116.1 mS/cm, and realize a maximum power density of 87 mW/cm2 at 80 °C. All these results point out that these long-lifetime PB-ASU-PBP membranes are promising for AEM applications.