Degradation of polymer-electrolyte membrane fuel cells tested at 80 and 95 °C using stack hardware

To overcome heat rejection limitations, especially in transport applications, polymer-electrolyte-membrane fuel cells (PEMFCs) are required to operate at elevated temperature > 80 °C. However, higher temperatures accelerate degradation of PEMFC stack components. To evaluate the impact of operation temperature on durability of PEMFCs, state-of-the-art membrane-electrode-assemblies (MEAs) were investigated in single-cell configuration using stack hardware. Two tests, consisting of 500 h constant-load operation at 80 °C and at 95 °C, also including electrochemical diagnostics along with local current density and temperature distributions monitorization, were performed and compared systematically. Irreversible performance and ECSA losses are respectively 27% and 7% higher at 95 °C than at 80 °C. However, due to drier conditions, reversible performance losses are 13% lower at 95 °C. Current density and temperature distributions are less homogeneous at 95 °C, and areas sustaining higher local currents and temperatures correlate with local catalyst-layer thinning. Contaminations of MEA by silicone due to degradation of gasket material at 95 °C deteriorate the water management increasing mass-transport losses at high current densities and impacting the cell response to dynamic load. The results highlight that improving PEMFC durability for operation at 95 °C requires not only robust MEAs but also adapted stack-hardware materials.