Robust poly(aryl piperidinium)/N-spirocyclic poly(2,6-dimethyl-1,4-phenyl) for hydroxide-exchange membranes

Herein, for realizing the high efficiency and long lifetime of hydroxide exchange membranes (HEMs) for alkaline membrane fuel cell (AMFC) applications, a series of robust poly(biphenyl piperidinium) (PBP)/6-azaspiro[5.5] undecane (ASU)-functionalized polyphenyl ether (ASU-PPO) membranes were prepared by a crosslinked strategy. Crosslinked PBP-ASU-PPO membrane combines the advantage of PBP and ASU-PPO membranes as well as addresses the problem of high water uptake of PBP and the insufficient film-forming property of ASU-PPO. As expected, these crosslinked PBP-ASU-PPO membranes exhibit commendably comprehensive performances, such as good ion conductivity, durability, and mechanical properties. The crosslinked PBP-ASU-PPO membrane reaches a maximum OH− conductivity of 128 mS/cm at 80 °C, accompanying with a 15.7% membrane swelling. Besides, only 13.6% degradation in Cl− conductivity was observed in PBP-ASU-PPO after alkaline treatment in 1 M NaOH at 80 °C for 2000 h. Besides, the selected PBP-ASU-PPO membrane achieves a maximum power density of 324 mW/cm2 at current density of 750 mA/cm2.