The effect of temperature and load as a stressor for proton exchange membrane fuel cells durability at intermediate temperatures

To improve the Proton Exchange Membrane Fuel Cells (PEMFCs) suitability for heavy-duty vehicles a higher operating temperature is required. However, a higher operating temperature is often associated with higher degradation rates. In this work we investigate the effects of temperature and load on the degradation of commercial state-of-the-art membrane electrode assemblies (MEAs) operating at intermediate temperatures (IT) between 80 and 120 °C during galvanostatic holds. Thorough electrochemical analysis was made together with transmission electron microscopy and modelling. As expected, a more rapid decrease in performance is observed at an increased operating temperature. The main loss in performance is linked to changes in the membrane and ionomer in the membrane electrode assembly. In particular, the membranes fail due to pinhole formation, resulting in higher hydrogen crossover. It is also seen that the ionomer in the cathode degrades faster at elevated temperatures, and that a lower applied load reduces the rate. Further analysis shows small and similar changes in the electrode thickness and particle sizes for all temperatures. Although an elevated temperature reduces the lifetime of a fuel cell, operation at elevated temperatures for shorter durations can be feasible, but the polymer electrolytes must be designed for higher temperatures. • Ageing of PEMFCs at intermediate temperature (80–120 °C) and high load. • Accelerated ageing at elevated temperatures. • Main cause of performance loss is the polymer in membrane and ionomer.