Quantifying Acceleration Factors for Electrode Degradation in Membrane Electrode Assembly Stress Tests for Heavy-Duty Fuel Cells

This study evaluates accelerated stress test (AST) protocols and introduces a framework for translating AST-derived degradation metrics into electrode lifetime predictions for heavy-duty vehicle fuel cells. Catalyst stability across ASTs of varying durations is compared using the electrochemically active surface area (ECSA) loss rate, which remains broadly consistent across catalyst systems and Pt loadings but is extremely sensitive to protocol design and exposure conditions. The corresponding cell performance decay is captured through ECSA loss and its impact on exchange current density and oxygen transport resistance. These degradation pathways are further shaped by catalyst particle size and composition, catalyst–support interactions, the catalyst–ionomer interface, and electrode microstructure. Building on these relationships, a practical procedure is developed to estimate electrode lifetime using the allowable ECSA loss predicted by the degradation model, the measured AST ECSA loss rate, and the duty-cycle lifetime of a reference catalyst with matching Pt loading. To generalize AST outcomes, an acceleration (loss) factor, ALF, is defined as the ratio of electrode lifetime to the AST duration required to reach an equivalent end-of-life ECSA loss. The ALF is uniquely determined by catalyst formulation, Pt loading, AST protocol, duty-cycle characteristics, end-of-life definition, and system-level mitigation strategies.