C2 and N3 substituted imidazolium functionalized poly(arylene ether ketone) anion exchange membrane for water electrolysis with improved chemical stability

Abstract

The effect of substituents at C2 and N3 positions of imidazolium functional group on various properties of the poly(arylene ether) ketone based anion electrolyte membranes was studied. The synthesized membranes were applied for alkaline water electrolysis using zero gap designed cell in order to evaluate their cell performances. All of the membranes exhibited better ionic conductivity and electrochemical performance than the commercial Fumasep FAA-3 membrane. The C2 methyl and N3 butyl substituted imidazolium-based membrane (PAEK-APMBI) specifically showed quite high ionic conductivity of 0.0154 S cm−1 and the voltage of 2.53 V at the current density of 2 A cm−2 (in 10 wt% KOH solution) at 60 °C, while those of Fumasep FAA-3 membrane were 0.013 S cm−1 and 2.63 V, respectively. Especially, the PAEK-APMBI membrane exhibited the excellent alkaline stability with the 96% IEC retention after long-term treatment in alkaline environment, while the Fumasep FAA-3 membrane illustrated a significant reduction in IEC to 38%. Based on those results, the PAEK-APMBI membrane would be a promising candidate for application in anion exchange membrane electrolysis system.