Heterogeneous porosity distributions of polymer electrolyte membrane fuel cell gas diffusion layer materials with rib-channel compression

摘要

In this study, X-ray Computed Tomography (X-CT) is used to study the structure of the bilayered gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells. This work presents a unique, calibrated segmentation procedure developed in-house to identify the distinct components of the bi-layer GDL, isolating the carbon fibre, the microporous layer and the void regions as individual phases. The novel use of the areal mass and areal volume of the GDL facilitates calibrated, reliable and repeatable multi-component segmentation and removes the high degree of subjectivity that might otherwise be encountered in typical thresholding procedures. Samples with and without MPLs are studied for the impact of rib channel compression on porosity profiles. Under the channel, the porosity profile is nearly identical to the uncompressed profile. Under the land region, there is a significant decrease in the GDL thickness. It is also observed that the majority of the compression is exhibited by the substrate region while the MPL undergoes significantly reduced compression. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.