Impact of Reinforced Polymer Electrolyte Membrane Scratch on Fuel Cell Durability Using 4D X-Ray Computed Tomography Technique

Abstract

PEMFCs, or Polymer Electrolyte Membrane Fuel Cells, can be used in both stationary power and transportation applications and are promising for use in heavy duty electric vehicles due to their high energy density, ability to be refueled quickly, and extended range, which are key challenges for battery-powered vehicles [1]. Despite these advantages, there are still obstacles preventing the widespread commercialization of PEMFCs, one of which is production cost [2]. To reduce manufacturing costs, it is imperative to ensure that quality control rejects and scraps are minimized. Moreover, enhancing component integration defect detection would ensure the durability of the fuel cell and enhance its operational lifetime. However, robust quality control requires a thorough understanding of potential non-uniformities and their effects on fuel cell performance and operational degradation.Non-uniformities of the membrane electrolyte assembly (MEA) can result in durability issues by damaging the membrane and making it more vulnerable to mechanical and chemical stress during the operation [3]. Several studies have been done on cation contamination and membrane pinholes and their effect on fuel cell performance and durability [4,5] but little attention has been paid to other types of non-uniformities such as membrane scratches and foreign particles, which may also conceivably affect durability [6]. By implementing 4D in-situ X-ray computed tomography (XCT) [7,8], the current work aims to track the evolution of scratches that appear on a reinforced membrane surface during fabrication and its specific objective is to determine the impacts of membrane scratches on membrane durability in fuel cells.The study was conducted by using small-scale fuel cells with GORE-SELECT® membranes that were intentionally scratched with a razor blade, subjecting them to combined chemomechanical membrane accelerated stress test (AST), and monitoring the membrane degradation and evolution of the scratches using 4D-XCT throughout the AST. During the fabrication step, the depth of scratches was regulated by a weak bond between the reinforcement layer and the perfluorosulfonic acid (PFSA) layer, i.e., the scratches did not tear through the reinforcement. Furthermore, the scratches did not adversely impact the initial cell performance. However, during AST operation the evolution of the scratched region was affected by several factors, including the friction between the layers of the membrane electrode assembly, the width of the scratch (Figure 1), the presence of membrane debris, and the extent of membrane strain. Additionally, it was observed that changes in the quality of catalyst layer transfer onto the scratched region can alter the degradation pattern and potentially create a self-mitigating mechanism. These findings may be used to develop more optimized quality control measures for membrane scratches in fuel cell production. Acknowledgements 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. Keywords: fuel cell; membrane durability; X-ray computed tomography; membrane scratch; manufacturing References [1] Cullen DA, Neyerlin KC, Ahluwalia RK, Mukundan R, More KL, Borup RL, et al. New roads and challenges for fuel cells in heavy-duty transportation. Nat Energy 2021;6:462–74. https://doi.org/10.1038/s41560-021-00775-z.[2] Whiston MM, Azevedo IL, Litster S, Whitefoot KS, Samaras C, Whitacre JF. Expert assessments of the cost and expected future performance of proton exchange membrane fuel cells for vehicles. Proc Natl Acad Sci U S A 2019;116:4899–904.[3] De Bruijn FA, Dam VAT, Janssen GJM. Review: Durability and degradation issues of PEM fuel cell components. Fuel Cells 2008;8:3–22.[4] Tavassoli A, Lim C, Kolodziej J, Lauritzen M, Knights S, Wang GG, et al. Effect of catalyst layer defects on local membrane degradation in polymer electrolyte fuel cells. J Power Sources 2016;322:17–25.[5] Lü W, Liu Z, Wang C, Mao Z, Zhang M. The effects of pinholes on proton exchange membrane fuel cell performance. Int J Energy Res 2011;35:24–30.[6] Kundu S, Fowler MW, Simon LC, Grot S. Morphological features (defects) in fuel cell membrane electrode assemblies. J Power Sources 2006;157:650–6.[7] Ramani D, Singh Y, White RT, Wegener M, Orfino FP, Dutta M, et al. 4D in situ visualization of mechanical degradation evolution in reinforced fuel cell membranes. Int J Hydrogen Energy 2020;45:10089–103.[8] White RT, Eberhardt SH, Singh Y, Haddow T, Dutta M, Orfino FP, et al. Four-dimensional joint visualization of electrode degradation and liquid water distribution inside operating polymer electrolyte fuel cells. Sci Rep 2019;9:1–12. Figure 1