On the Tuning of the MPL’s Cracked Area for Optimizing the Performance of Polymer Electrolyte Fuel Cells

The cracks in Micro Porous Layers (MPL) can have a significant impact on the performance of Polymer Electrolyte Fuel Cells (PEFCs) [1–4]. For such a reason, the interest in researching and understanding the crack formation processes, as well as studying their final morphology, is rapidly increasing [2-4]. In this contribution, we propose a method for tuning the MPL’s cracked area and an analysis of the superficial and intersected cracks through a combination of optical microscopy, XTM (X-ray Tomographic Microscopy), and image processing. An example of optical images of MPLs with different cracked areas and the results of the segmentation process applied to them is reported in the Figure. After segmentation, the calculation of the cracked area yields values of about 4.5%, 1%, and < 0.1%, respectively, for the images in the Figure. By having good control and thorough characterization of the cracked area, we target a conclusive correlation between the cracked area and fuel cell performance. This is made possible by testing the cells in dry and wet conditions and by analyzing how the polarization curve and the oxygen transport resistance vary for MPLs with different amounts of cracked areas. In such a way, we aim to answer two questions: “Are the cracks beneficial for fuel cell performance?”; and most importantly: “What is the amount and type of cracks that optimize the fuel cell performance?”. References: Z. Chen et al. “Crack evolution during the film drying process of fuel cell microporous layer ink.” In: Colloids and Surfaces A - Physicochemical and Engineering Aspects 650.129283 (2022). J. Dai et al. “Analysis on the influence of crack structure on MPL transmission properties.” In: Journal of Power Sources 562.232790 (2023). S. Wang et al. “Enhancing the properties of water and gas management for proton exchange membrane fuel cells via tailored intersected cracks in a microporous layer.” In: Journal of Power Sources 533.231402 (2022) Z. Chen et al. “Interrelation between ink viscoelasticity and crack structure of fuel cell microporous layer.” In: Fuel 360.130629 (2024). Figure 1