Impact of Porosity Gradients within Catalyst Layer and MPL of a PEM Fuel Cell on the Water Management and Performance: A Neutron Radiography Investigation

Abstract

The influence of porosity modification of both the cathode microporous layer (MPL) and catalyst layer (CL) of a low temperature polymer electrolyte membrane fuel cell (PEMFC) is studied with a neutron radiography technique to determine the water distribution and transport inside the cell. Three types of cathode MPLs with varying porosity distributions are made by introducing Chemisnow® monodisperse spherical polymer particles with 1.5 μm and 30 μm diameters inside the MPL slurry. CLs with three different porosities are manufactured by incorporation of 0 to 10 wt.% polystyrene particles with 0.5 μm diameters. Water thicknesses are measured inside the cell components at relative humidity of 120% with an increasing current density up to 1 A/cm². The results indicate that introducing micro pores into the structure of the MPL and CL may lead to the extraction of the excess water through these pores, leaving smaller pores accessible for the reaction gases and better cell performance.