Assessment of degradation in Ion pair membrane high temperature PEM fuel cells using commercial and customized catalysts under varied operating conditions

Abstract

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) present considerable advantages, such as high energy efficiency and tolerance to fuel impurities; however, durability issues and catalyst costs remain major barriers to commercial adoption. This study systematically investigates the degradation behaviors in Ion pair membrane-based HT-PEMFCs under realistic operational conditions, specifically steady-state operation and dynamic start-stop cycling operation. Membrane electrode assemblies (MEAs) employing standard and customized recycled platinum (Pt)-based catalysts were critically evaluated. Electrochemical characterization techniques, including polarization curves, electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV), were employed to monitor the performance degradation and identify underlying electrochemical mechanisms. Post-mortem analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD) were also employed to identify the structural degradation pathways inside the MEAs. The results demonstrated that customized recycled catalysts performed comparably or better than fresh catalysts under steady-state conditions, with a degradation rate of approximately −21 μ V h −1 compared to −24 μ V h −1 for standard catalysts. However, customized recycled catalysts exhibited significantly higher accelerated degradation under dynamic cycling, with voltage degradation rates of −236 and −656 μ V h −1 , compared to −75 and −370 μ V h −1 for standard catalysts. Moreover, the post-mortem results showed that the Pt particle agglomeration and membrane thinning phenomenon were more pronounced for the MEAs with customized recycled catalysts, indicating more severe degradation.