Effects of water accumulation in the proton exchange membrane and the gas diffusion layer on the power generation performance of PEFC

Abstract

Water management in a polymer electrolyte fuel cell (PEFC) is a key topic for the PEFC operation. It is well known that the water accumulation in the gas diffusion layer (GDL) increases the polarization resistance, whereas the increases of the water content, λ, in the proton exchange membrane (PEM) decreases the proton conductivity. In this study, neutron radiography and the electrochemical impedance spectroscopy (EIS) were employed simultaneously for evaluating the effect of the water accumulation in the GDL and the PEM on the performances. Water accumulation in the channel disturbed the air supply resulting in the rapid increase of the polarization resistance. Relation between the water contents and the polarization losses in a PEFC with and without MPL was examined. Ionic conductivity can be evaluated as a function of the water content in the PEM regardless of the with or without MPL and geometries of the gas channel. However, the effect of the water contents on the ionic conductivity was less at low λ than a correlation proposed by Springer et al. for λ > 1.