Imidazolium functionalized polysulfone anion exchange membrane for fuel cell application

Abstract

Alkaline anion exchange membrane (AEM) is the key material for anion exchange membrane fuel cells (AEMFC), which can potentially outperform proton exchange membrane fuel cells due to facile oxygen reduction kinetics and wide catalyst choices. Quaternary ammonium (QA) AEMs have been shown to be low in alkaline stability, and their fabrication often involves carcinogenic chemicals. Therefore, recent years have witnessed emerging research efforts in developing non-QA AEMs. As part of these efforts, this work reports imidazolium AEMs that were fabricated via functionalization of chloromethylated polysulfone with methylimidazole. The membrane exhibited ion exchange capacity, conductivity and thermal stability that are comparable or superior to those of conventional membranes. A H₂/O₂fuel cell using the synthesized membrane yielded a peak power density of 16 mW cm⁻². Although this result is not high and the membrane stability is still an issue, the potential of using imidazolium AEM in a fuel cell is seen. This work opens up a new route for non-QA AEM design and fabrication. Based on the chemistry involved, it is anticipated that different chloro- or bromomethylated aromatic polymers and imidazole derivatives may be used to optimize membrane conductivity and stability, thus offering the possibility to fabricate high performance AEM.