Phase-contrast X-ray imaging of the gas diffusion layer of fuel cells.

The understanding of and in situ observation of the transport and distribution of water in carbon-paper gas diffusion layers (GDLs) using non-destructive imaging techniques is critical for achieving high performance in polymer electrolyte fuel cells (PEFCs). To investigate the behavior of water in GDLs of PEFCs, phase-contrast X-ray imaging via X-ray interferometric imaging (XII) and diffraction-enhanced imaging (DEI) were performed using 35 keV X-rays. The XII technique is useful for the radiographic imaging of GDLs and in situ observations of water evolution processes in operating PEFCs. DEI provides a way for tomographic imaging of GDLs in PEFCs. Because high-energy X-rays are applicable to the imaging of both carbon papers and heavy materials, which make up PEFCs, phase-contrast X-ray imaging techniques have proven to be valuable for investigation of GDLs.