A new insight into the effects of agglomerate parameters on internal dynamics of proton exchange membrane fuel cell by an advanced impedance dimension model

Abstract

The oxygen reduction reaction with a relatively slow reaction rate is critical for proton exchange membrane (PEM) fuel cell performance. At present, a substantial part of the previous numerical study respecting the optimization design of the cathode catalyst layer (CCL) mainly focuses on the polarization curve output and oxygen local transport. In this paper, for the first time, a two-dimensional multiphase PEM fuel cell impedance model coupled with an improved electrochemical kinetics model considering the cathode agglomerate construction is proposed, which can reproduce the measured electrochemical impedance spectroscopy (EIS) under different current densities, reactant stoichiometries and inlet humidity only with a single boundary set. Based on this, the effects of five CCL design parameters (Pt loading, carbon loading, catalyst layer thickness, ionomer volume fraction, and agglomerate radius) on the EIS and critical internal dynamics are comprehensively investigated. Meanwhile, each dynamics loss of simulated EIS is identified by the distribution of relaxation time and equivalent circuit model to support quantitative analysis. These works offer a deeper understanding and new insight into the effects of CCL parameters on PEM fuel cell internal dynamics, which can help material optimization and system controller design.