Cold start cycling durability of fuel cell stacks for commercial automotive applications

System durability is crucial for the successful commercialization of polymer electrolyte fuel cells (PEFCs) in fuel cell electric vehicles (FCEVs). Besides conventional electrochemical cycling durability during long-term operation, the effect of operation in cold climates must also be considered. Ice formation during start up in sub-zero conditions may result in damage to the electrocatalyst layer and the polymer electrolyte membrane (PEM). Here, we conduct accelerated cold start cycling tests on prototype fuel cell stacks intended for incorporation into commercial FCEVs. The effect of this on the stack performance is evaluated, the resulting mechanical damage is investigated, and degradation mechanisms are proposed. Overall, only a small voltage drop is observed after the durability tests, only minor damage occurs in the electrocatalyst layer, and no increase in gas crossover is observed. This indicates that these prototype fuel cell stacks successfully meet the cold start durability targets for automotive applications in FCEVs.