Durable and high-performance perfluorinated anion exchange membrane for pure-water-fed electrolysis

Durable and efficient anion exchange membranes (AEMs) are essential for the sustained functioning of costeffective anion exchange membrane water electrolyzes (AEMWEs). Herein, perfluoropiperazine (PFDMP-OH) and perfluoropiperidine (PFMEP-OH) AEMs for water electrolysis were successfully synthesized by a simple grafting reaction. The perfluorinated backbone and hydrophilic piperidinium and piperazinium end-group side- chain structures enhances phase separation to construct interconnected hydrophilic channels for anion transport. As a result, these AEMs demonstrated exceptional hydroxide conductivity (>90 mS cm-1 at 80 C-degrees) and remarkable dimensional stability (<50% volume swelling at 80 degrees C C-degrees). On the one hand, the chemically robust perfluoroalkyl backbone can resist the attack of hydroxide ions. On the other hand, the conformational constraints imposed by the cation's low loop strain and loop structure can effectively weaken nucleophilic substitution and Hoffmann elimination reactions. Consequently, the conductivity retention of PFDMP-OH AEMs attained 98.4% after immersion in a 1 M KOH solution at 80 C-degrees for 240 h. Impressively, the PFDMP-OH-based membrane electrode assembly (MEA) exhibited a current density of 387 mA cm(-2 )at 1.9 V in the AEMWE with pure water feed, which was 3.3 times higher than the commercial FAA-3-50 alkaline membrane. This work provides a viable strategy to achieve durable and high-performance AEMs, which are promising candidates for AEMWE applications.