Simultaneous neutron imaging of six operating PEFCs: Experimental set-up and study of the MPL effect

A new experimental set-up was developed to perform simultaneous high resolution in-plane neutron imaging of six differential polymer electrolyte fuel cells (PEFCs). Beyond offering the major advantage of using the neutron beam time more efficiently, this set-up allows applying identical operation conditions to all cells (e.g. temperature, relative humidity, gas composition, and gas flow) and is therefore dedicated to the systematic study of different design parameters (e.g. materials, geometry, and compression).A first set of experiments demonstrated the influence of the microporous layer (MPL) of the gas diffusion layer (GDL) on the performance and on the liquid water distribution in the porous media by means of four cells (MPL on anode, on cathode, on both sides and no MPL). The mass transport losses observed in absence of MPL on cathode side are attributed to flooding in the cathode catalyst layer (CL) and/or water film formation at the CL/GDL interface. The presence of MPL has no major influence on the saturation level of the GDLs. In particular, the insertion of a MPL on cathode side does not reduce the saturation level of the cathode GDL.

► A set-up is realized for high-resolution simultaneous neutron imaging of six cells.
► The effect of the presence of a microporous layer (MPL) is shown.
► MPLs do not change the average water content of the gas diffusion layers (GDLs).
► Absence of cathode MPL shifts the water accumulation peak towards the electrode.
► Absence of cathode MPL leads to electrode flooding and/or to water film formation.