Compression Modeling and Transport Characterization of the PEM Fuel Cell Diffusion Medium

Despite tremendous progress in recent years, a pivotal performance limitation in PEM fuel cells manifests in terms of mass transport loss owing to liquid water transport and resulting flooding. A key contributor to the mass transport loss is the cathode gas diffusion layer (GDL) due to the blockage of available pore space by liquid water thus rendering hindered oxygen transport to the active reaction sites in the electrode. The GDL, typically a non-woven carbon paper or woven carbon cloth, thus plays an important role in the overall water management in PEM fuel cells. The underlying pore-morphology and the pore wetting characteristics have significant influence on the flooding dynamics in the GDL. Another important factor is the role of cell compression on the GDL microstructural change. In this work, we investigate the influence of GDL microstructure change under compression on the transport behavior. We will present an improved compression model based on the micro finite element approach. The compression of reconstructed GDL microstructures along with effective property estimation and transport characterization are elucidated.