Ice Formation and Current Distribution in the Catalyst Layer of PEM Fuel Cell at Cold Start

In polymer electrolyte fuel cells (PEFCs), the freezing of produced water induces the extreme deterioration of the cell performance below zero. This phenomenon is serious problem in cold regions and is needed to be solved to achieve the practical use of PEFCs. In this study, we investigated the ice formation and the reaction rate in the cathode catalyst layer (CL) using a CRYO-SEM and a three-phase boundary model to clarify the freezing mechanism in the cold start at -20oC. The observation results showed that the ice distribution formed in the CL is changed by the operation time and the current density. In particular, in a case of large current density, it was shown that ice grows from the membrane side to the gas diffusion layer (GDL) side. This process can also be analyzed in detail by the model that calculates the reaction rate in the CL.