Imidazolium-functionalized carbon nanotubes crosslinked with imidazole poly(ether ether ketone) for fabricating anion exchange membranes with high hydroxide conductivity and dimension stability

Abstract

Abstract Simultaneously improving the hydroxide conduction capacity and anti-swelling property of anion exchange membranes (AEM) is a big challenge in the field of fuel cells. In this work, the poly (vinyl imidazole) functionalized carbon nanotube (PVI@CNT) was synthesized as a dual functional nanofiller and introduced into the imidazole poly(ether ether ketone) (IPEEK) matrix. The imidazolium groups on the PVI@CNT offer additional ion conducting sites to improve the hydroxide conductivity. The imidazolium groups also react with the IPEEK to form a crosslinking structure along the nanotubes, thus ensuring favorable anti-swelling property. The nanohybrid membrane with 15 wt % PVI@CNT (IPEEK/PVI@CNT-15) shows a maximum conductivity of 121 mS cm -1 at 70 o C, 100% relative humidity (RH). Meanwhile, the crosslinking structure suppresses the swelling degree from 42.0% (pristine IPEEK) to 17.8% (IPEEK/PVI@CNT-15). The single H 2 /O 2 fuel cell performance of the membrane electrode assembly (MEA) with IPEEK/PVI@CNT-15 membrane reveals a high power density of 128.7 mW cm −2 . Moreover, the incorporation of the PVI@CNT also enhances the alkali stability and the thermal stability of the nanohybrid membranes.