X-Ray Tomography of Water in Operating Fuel Cell
Polymer electrolyte fuel cells (PEFC) convert the chemical energy of hydrogen with a high efficiency (40-70 %) directly into electricity. The product of the overall reaction is water, produced at the cathode of the cell. The interaction of liquid water with the porous structures of the cell is one of the mechanisms in the PEFC that are commonly believed to be key for further optimization with regard to performance, durability and cost. Synchrotron based X-ray tomographic microscopy (XTM) allows for the simultaneous in situ visualization of the water and carbonaceous structures in the gas diffusion layer (GDL) on the pore scale level [1, 2]. In-situ XTM scans of operating PEFC are performed within a few seconds per scan and pixel sizes of 2 - 3 µm. Experiments are made at the TOMCAT beamline of the Swiss Light Source (SLS).
The figure shows XTM surface renderings of the cathode channel with flow field plate, GDL, liquid water and catalyst layer.