Microscopic Observation of Ice Distribution in PEM Fuel Cell at Cold Start

Abstract

In Polymer electrolyte membrane fuel cells (PEFCs), freezing of produced water induces the extreme deterioration of cell performance below zero. This phenomenon is a serious problem in cold regions and is needed to be solved to achieve the practical use of PEFCs. In this study, we investigated ice distribution at the cold start in a PEFC using an optical microscope and a CRYO-SEM to clarify the freezing mechanism. The observation results showed that the cold start at −10°C makes ice at the interface between the cathode catalyst layer (CL) and the micro porous layer of gas diffusion layer. Little ice was, however, observed in the cold start at −20°C, which indicated the ice formation inside the CL. The CRYO-SEM observation was conducted at −20°C to investigate the ice formation inside the CL, and this identified the effects of the current density and the cathode gas species on the ice distribution.