Observation of dynamic liquid water transport in the microporous layer and gas diffusion layer of an operating PEM fuel cell by high-resolution soft X-ray radiography

In-situ observation of liquid water transport in the microporous layer (MPL) and gas diffusion layer (GDL) of an operating proton exchange membrane fuel cell (PEMFC) was performed using high-resolution soft X-ray radiography. The amount of liquid water accumulated in the MPL and GDL increases with increasing in current density. The amount of liquid water in the MPL is low near the catalyst layer and higher toward the GDL side. The liquid water is transported to the GDL mainly through the cracks in the MPL. The dynamic liquid water transport from the cracks in the MPL to the interconnected pores in the GDL was observed.

► In-situ observation of liquid water transport in a PEMFC's MPL and GDL is performed.
► High-resolution soft X-ray radiography is used to observe the liquid water.
► The liquid water in the MPL and GDL increases with increasing in current density.
► The liquid water in the MPL is low near the CL and higher toward the GDL side.
► The dynamic liquid water transport from the MPL cracks to the GDL pores is observed.