Microscale X-ray tomographic investigation of the interfacial morphology between the CL and MPL in PEMFCs Prass, Sebastian; Hasanpour, Sadegh; Sow, Pradeep Kumar; Merida, Walter; Phillion, André
The interfacial morphology between the catalyst layer (CL) and micro porous layer (MPL) influences the properties and performance of proton exchange membrane fuel cells (PEMFCs). Here we report a direct method to investigate the CL-MPL interfacial morphology of stacked and compressed gas diffusion layer (GDL with MPL)-catalyst coated membrane (CCM) assemblies. The area, origin and dimensions of interfacial gaps are studied with high-resolution X-ray micro computed tomography (X-μCT). The interfacial gap area (fraction of the CL-MPL interface separated by gaps) is higher for GDL-CCM assemblies with large differences in the surface roughness between the CL and MPL but reduces with increasing compression and with increased similarity in roughness. Relatively large continuous gaps are found in proximity to cracks in the MPL. These are hypothesized to form due to the presence of large pores on the surface of the GDL. Relatively small gaps are induced by the surface roughness features throughout the CL-MPL interface. From the results, smaller pores on the GDL surface serving as substrate for the MPL could reduce the number of MPL crack-induced gaps. Moreover, adjusting the CL and MPL surface roughness parameters to achieve similar orders of roughness can improve the surface mating characteristics of these two critical fuel cell components.
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