Membrane Integrity in the Presence of Foreign Particles in the Membrane Electrode Assembly

Cost-effective, large-scale production of reliable proton exchange membrane fuel cells (PEMFCs) is crucial to meet growing green energy demands. High-throughput production of PEMFCs relies on heavy machinery, which may inadvertently introduce foreign particles into the membrane electrode assembly (MEA) and affect PEMFC durability and performance 1–3 . A wide variety of particles could conceivably be introduced into the MEA and may or may not be detected. Thus, understanding the potential impacts of these particles is essential. The objective of the present work is to determine the impacts of foreign particle dimensions, shape, hardness, and chemical composition on membrane integrity and durability in PEMFCs. To accommodate a suitably wide range of particles for testing, the study focuses on assessing the nature and extent of membrane damage upon fuel cell assembly, conditioning, and initial operation as well as the prospects of mitigation. Composite material (CM) spheres with diameters of 5, 15, 60, and 100 µm along with 500 µm spherical glass beads, 50 µm slightly oxidized iron (Fe) particles, and stainless steel 316L particles of 50 and 500 µm were selected for this research. The particles were strategically placed between a mechanically reinforced GORE-SELECT® membrane (MemA) and the cathode catalyst layer. An MEA was fabricated using the particle-laden catalyst coated membrane (CCM) and assembled within a small-scale fixture (SSF) fuel cell. Non-invasive 3D characterization through X-ray computed tomography 4 imaging revealed that CM particles completely dissolved when measuring up to 15 µm in diameter, creating pinhole-like voids in the CCM. Additionally, a slightly oxidized Fe particle of approximately 55±5 µm also showed complete dissolution, demonstrating that the dissolution of particles was mainly determined by their chemical composition and, to a lesser extent, their size. Larger particles, specifically those measuring 100 µm or more, caused damage in the MEA structure, including deformation of the gas diffusion layer (GDL) and a torus-shaped void in the catalyst layer. Early fabrication damage during the decal transfer process was commonly noted, especially as the surface features of the particles became increasingly random. Additionally, as the size and hardness of the particles increased, especially the SS316L 500 µm particles, significant permanent membrane rupture, GDL damage, and cavities in the MEA were observed. Figure 1 illustrates the types of observed MEA damage associated with particle sizes. As the particle size increased, the prevalence of some damage types also rose, highlighting the importance of mitigating damage from larger particles. Performance analysis indicated that cyclic voltammetry and polarization curve data could effectively identify early cell failures caused by damage incurred by the particles. Different shapes and surface morphologies of SS316L particles were further tested with a thinner chemically and mechanically reinforced GORE-SELECT® membrane (MemB) for mitigation purposes, as they caused the maximum damage to the MemA MEA. It was found that MemB could accommodate all four selected particles, despite varying degrees of surface randomness, without any membrane ruptures after the decal transfer phase. However, significant permanent damage to other MEA components remained evident. Keywords: Quality control, cost reduction, X-ray computed tomography, foreign particles Acknowledgments This research was supported by the Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, Western Economic Diversification Canada, Ballard Power Systems, and W.L. Gore & Associates. This research was undertaken, in part, thanks to funding from the Canada Research Chairs program. References J. Chen, H. Liu, Y. A. Huang, and Z. Yin, J. Manuf. Process. , 23 , 175–182 (2016). M. Bahrami et al., J. Electrochem. Soc., 170 , 114527 (2023). N. Kumar et al., J. Electrochem. Soc. , 171 , 074513 (2024) Y. Singh, F. P. Orfino, M. Dutta, and E. Kjeang, J. Electrochem. Soc. , 164 , F1331–F1341 (2017). Figure 1

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