Post-Mortem Analysis on Low Temperature Proton Exchange Membrane Fuel Cells (LT-PEMFC) after Small and High Frequencies Current Ripple Solicitations

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Understanding the durability of proton exchange membrane fuel cells (PEMFCs) is essential to ensure their long-term viability in energy applications, driving to reliable performance and minimal environmental impact. At the system level, static converters play a crucial role as these electronic devices convert the electrical energy produced by PEMFCs into a usable form for a variety of applications. However, they generate undesired high and low frequencies current harmonics, possibly introducing PEMFC further degradation. Previous studies on LT-PEMFCs have shown that low-frequency current harmonics have a more significant impact on accelerated aging than high-frequencies ones [1–3]. Notably, this accelerated aging is associated with an increase in catalyst nanoparticle size, agglomeration of particles, and a loss of platinum [1]. In this study, electrical current profiles If(t) = 0.8 ± 0.16sin(2πft) A.cm-2 where f = 0, 1, 10 and 10,000 Hz were applied on individual commercial 25 cm2 membrane electrode assemblies (MEAs) for several hundreds of hours. Performance monitoring was achieved via periodical polarization curves. Post-mortem analyses were conducted on each MEA after aging, involving disassembly and separation of the various layers. (Micro)structural characterizations (by SEM, TEM and XRD) and chemical analyses (by using FTIR or Raman spectroscopy) were conducted to establish correlations with degradation observed through electrochemical measurements, including ECSA-losses and increase in cross-over current determined by cyclic voltammetry (Figure 1). Conclusions regarding the switching frequency at which static converters that will have or not an impact on the PEMFC long-term performances will be presented. This work is supported and financed by the Occitanie region via le pôle de recherche et d’innovation sur l’hydrogène en Occitanie (RHyO) and by the IRT Saint-Exupéry with the HeMoWHy project (financing from industrial members: Airbus, Flying Whales, Liebherr Aerospace and Aerostack GmbH). This project has received government funding managed by the Agence Nationale de la Recherche (ANR) under the France 2030 future investment program, under reference ANR-10-AIRT-01. M. Uno and K. Tanaka, Journal of Power Sources, 196, 9884–9889 (2011). J.-H. Kim et al., Journal of Power Electronics, 11, 82–89 (2011). B. Wahdame et al., 2008 IEEE International Symposium on Industrial Electronics, 1495–1500 (2008). D. Rohendi et al., International Journal of Hydrogen Energy, 40, 10960–10968 (2015). Figure 1: Analysis of catalyst degradation as a function of the applied frequency: (a) XRD patterns4, (b) Rietveld refinement result on Fresh sample (c) determination of Pt crystallite size via Rietveld refinement, (d) Catalyst ElectroChemical Surface Area (ECSA) measurements using cyclic voltammetry, and (e) cross-sectional observations of MEA layers using SEM. Figure 1

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