Quantification on degradation mechanisms of polymer exchange membrane fuel cell cathode catalyst layers during bus and stationary durability test protocols

Simulating bus and stationary protocols are designed to study the durability and degradation mechanisms of proton exchange membrane fuel cells. A quantitative method combined with characterization techniques, including electrochemical impedance spectroscopy, X-ray fluorescence spectroscopy and X-ray diffraction spectroscopy, is applied to distinguish performance degradation. Experimental results show that, for proton exchange membrane attenuation, chemical attenuation due to high cathode potential with long duration is more severe than mechanism attenuation due to dynamic load. For cathode catalyst layer decay, the principal reason under bus condition is particles growth (∼35%), followed by Pt dissolution (∼34%). In contrast,∼43% ECSA loss results from ionomer/catalyst interface loss under stationary condition. Such information indicates that the bus condition results in particles growth and Pt dissolution while the stationary condition induces ionomer/catalyst interface loss in the cathode catalyst layer. Combining more realistic protocols and quantitative analysis method can reveal the relationship between operating conditions of fuel cell in realistic road and MEA degradation. • Simulating stationary and bus protocols are used to study MEA degradation. • The attenuation mechanisms of MEA under these two protocols is proposed. • Chemical decay by durable high-potential affects severely PEM durability. • Particle growth and Pt dissolution cease CL decay under bus protocol. • Ionomer loss ceases CL degradation under stationary protocol.