Visualization of dynamic behavior of liquid water in the microporous layer of polymer electrolyte fuel cell during water injection by time-resolved X-ray computed tomography

Abstract

Liquid water behavior in the microporous layer (MPL) of a polymer electrolyte fuel cell (PEFC) was investigated using time-resolved X-ray computed micro-tomography (CT) to elucidate the unsteady flow during flooding. The water was injected into an MPL laminated on top of the substrate of a gas diffusion layer (GDL) to simulate the cathode in an operating PEFC. A CT scan time as high as 4.2 s was achieved, which enabled capture of the water motion in MPL pores with sizes of ca. 30 and 100 μm. Dynamic water transport from a hydrophobic MPL pore to the hydrophilic carbonaceous binder that bonds the substrate fibers was observed.