A Comparison of Laboratory Based and Synchrotron Based Nano X-ray CT for PEFC Micro Porous Layer

The nano-structure of micro porous layers (MPLs) used in polymer electrolyte fuel cells (PEFCs) has introduced new challenges to existing tomography techniques. X-ray Microscopy (XRM) has fundamental abilities such as: 1) non-destructive 3D tomography, 2) high energy, enabling deeper penetration and internal imaging, and 3) strong absorption and phase contrast dependence to elemental composition. The nanostructure of an MPL was analyzed by two nano-scale XRM techniques: 1) Xradia Ultra XRM-L200 laboratory based X-ray microscope, and 2) synchrotron based transmission X-ray microscope (TXM) at beamline 32-ID C of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The synchrotron X-ray CT resulted in better resolution and edge sharpness at the solid/pore boundary. Additional comparison between these techniques is performed by obtaining the key MPL nanostructural parameters and transport property such as bulk porosity, pore size distribution, tortuosity, and effective oxygen diffusivity.