Highly conductive and robustly stable anion exchange membranes with a star-branched crosslinking structure

In order to improve the ionic conductivity and durability of anion exchange membranes (AEMs), novel ether free AEMs are prepared based on 6-bromo-1-hexanol quaternized poly(terphenyl piperidine)s by construction of a star-branched crosslinking structure via a crosslinker of 1,3,5-tris(bromomethyl)benzene. The star-branched crosslinking network enhances the dimensional stability and mechanical property without occupying the active sites for cation production. Suitable microphase separations with ionic cluster spacing within 19.68–20.72 nm are formed according to the SAXS results. The proposed AEMs exhibit hydroxide ion (OH‾) conductivity ranging from 118 to 136 mS cm−1 at 80 °C. The dense crosslinking structure and flexible side chains endow the AEMs with excellent resistance against the attack of OH‾ ions. About 80% of the conductivity retention rate is achieved after immersing the AEMs in 1 mol L−1 KOH aqueous solutions at 80 °C for 1600 h. A single H2/O2 fuel cell employing the prepared membrane as the electrolyte exhibits a peak power density of 639 mW cm−2 at 60 °C without back pressure.