Simulation of chemical degradation of reinforced fuel cell membranes in the presence of Fe and Ce cations

An extended lifetime of thin ionomer membranes in the presence of Fenton’s cations [iron (Fe n+ )] and chemical reinforcement additives [cerium (Ce m+ )] without performance loss is essential for the successful commercialization of proton exchange membrane fuel cells. Therefore, the role of these influential cations needs to be comprehensively investigated through both experimental and simulation approaches. In the present work, a transient 1D reaction-transport model of the membrane electrode assembly is used to simulate the chemical degradation mechanism of mechanically reinforced fuel cell membranes with and without chemical reinforcement. The model is used to determine temporal membrane thinning and validated with experimental data. Subsequently, the critical threshold limits of the Fe and Ce cation concentrations are determined, beyond which they are detrimental to the fuel cell durability and/or performance. Based on the results, the critical threshold for Fe-ions, regardless of membrane thickness, should be below 50 ppm for an unmitigated membrane to ensure durability. In the presence of Ce ions, the rate of chemical degradation is significantly reduced due to radical scavenging across a wide range of Fe-ion concentrations. A nominal Ce-ion loading of 0.8±0.2% of the sulfonic acid group concentration is adequate to extend fuel cell lifetime without compromising performance.