Hydrocarbon Proton Exchange Membranes for Fuel Cells: An Antioxidant Study

In fuel cells, hydrocarbon proton exchange membranes (HC PEMs) suffer from insufficient chemical stability caused by oxidative aging, hampering their commercial viability. Using sulfonated poly(ether ether ketone) as a model HC PEM, we conduct a first-of-its-kind systematic screening of relevant antioxidants, combining ex situ Fenton tests and in situ fuel cell tests. Ionic additives based on cerium, as well as phosphonic-acid-derived (12-phosphonododecyl)phosphonic acid (PDPA), are found to significantly increase membrane lifetime. While ionic additives impart a performance penalty, PDPA proves to be not only an effective antioxidant but also benign regarding cell performance, revealing its potential for use in HC PEMs.