Performance Degradation of High-Temperature PEM Fuel Cells under Anode Gas Contamination

Kurzfassung

During natural disasters, maintaining the operation of critical infrastructure, including healthcare, energy, and food systems, requires reliable and uninterrupted power supply. High-temperature proton exchange membrane fuel cells (HT-PEMFCs) represent a promising technology for resilient power generation, particularly due to their higher tolerance to impurities in reformate fuel streams [1]. When fuels are derived from processes such as methanol reforming or ammonia cracking, trace contaminants such as CO, NH₃, and H₂S may be present and can affect catalyst performance and long-term stability. Within this context, the EU Clean Hydrogen project RESCUE is developing a containerized HT-PEM fuel cell system with dual-fuel capability, using methanol or hydrogen. Long-term measurements were planned at the single-cell level over 500 hours of operation at 0.3 A cm⁻² to better understand the fundamental degradation mechanisms associated with such contaminants. Electrochemical characterization methods—including polarization curves, linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS)—were performed before (BoT) and after (EoT) the 500h operation. To establish the benchmark, reference measurements were conducted at the single-cell level under contamination-free conditions using PBI and Ion Pair MEAs from Advent Technologies. The voltage response to the applied current during the polarization curves in the case of PBI MEA remained comparable (Figure 1a) despite a drop in electrochemically active surface area (ECSA) and ohmic resistance of the PBI MEA over the 500h operation. In contrast, the Ion Pair MEA exhibited improved performance (Figure 1b), owing to reductions in charge-transfer and oxygen transport resistances. The higher peak power density of the PBI MEA can be attributed to the Pt-alloy catalyst used in the cathode, which yields a higher ECSA, whereas the Ion Pair MEA employs a Pt-only cathode catalyst. Further experiments will investigate the influence of catalyst contaminants—including NH₃, H₂S, and CO - as well as inert gases such as Ar, He, and N₂, to evaluate their impact on HT-PEMFC performance and long-term operational robustness under reformate fuel conditions. Particular attention will be given to changes in EIS characteristics and cyclic voltammetry, supported by evidences from ex-situ analysis.