Toward a representative accelerated stress test for PEMFC stacks in automotive applications

An accelerated stress test at stack level was developed and validated to replicate the main aging mechanisms observed in automotive applications using a commercial Proton Exchange Membrane stack. The test achieved approximately 10 % voltage loss at 1.0 A.cm−2 after 130 h of operation. Electrochemical impedance spectroscopy and distribution of relaxation times analyses revealed a 30 % decrease in the proton transfer time constant at a current density of 0.2 A.cm−2, alongside an average increase in charge transfer resistance of 47 % at 0.2 A.cm−2 and 53 % at 0.5 A.cm−2, indicating degradation of key components—the membrane and catalyst layer. A reference test based on actual bus data was also used to validate the AST and to calculate the degradation acceleration factor. The accelerated stress test effectively accelerated degradation at the stack level by simulating operational conditions that replicate in-field aging mechanisms, providing a benchmark toward a viable stack durability assessment.