Breakthrough/drainage pressures and X-ray water visualization in gas diffusion layer of PEMFC

The primary role of the gas diffusion layers (GDLs) in polymer electrolyte membrane fuel cells (PEMFC) is to maintain the delicate balance between water retention and removal in GDLs. Water management in the fuel cell is related to the breakthrough pressure at which water starts to pass through GDL, and the drainage pressure, which is maintained after the breakthrough. These pressures are both related to water management in fuel cells. Here we measured these pressures for two different GDLs and used X-ray tomography to visualize the water distributions within them. We then relate the variations in liquid pressures to the visualization and discuss water management in PEMFC.

► Breakthrough and drainage pressures of the GDL were measured.
► Water distributions were observed by X-ray tomography, under controlled pressure.
► Microporous layers dominantly control the water behavior in the GDL.