Simulation of EIS spectra and polarization curves based on Ni/YSZ patterned anode elementary reaction models

Abstract

Analysis of recent experimental impedance spectra and polarization curves of nickel/yttria-stabilized zirconia (Ni/YSZ) patterned anode of a solid oxide fuel cell (SOFC) are used to interpret the CO electrochemical oxidation processes. A one dimensional (1D) comprehensive electrochemical oxidation model is proposed for the prediction of both the polarization curve and EIS spectra of a patterned anode SOFC. The model incorporates the ionic/electronic conductor microstructure, CO charge transfer steps, adsorption/desorption kinetics and surface diffusion processes. The model is used for the quantitative investigation of the cell performance as well as electrochemical impedance, and can bring a bridge for the experimental results and elementary reactions. The results indicated that the CO charge transfer mechanism is applicable to different temperature and polarization voltages. The concentration distribution of surface species near the three-phase boundary (TPB) is predicted. The surface concentration gradient is larger at lower temperatures and higher polarization voltages. Thus, surface diffusion may be one of the important limiting steps at lower temperature and higher polarization voltage.