Analytical transfer function to simulate the dynamic response of the finite-length Warburg impedance in the time-domain
Samuel Cruz-Manzo, Paul Greenwood
Abstract
Based on fundamental electrode theory, an analytical transfer function to simulate the frequency impedance spectrum of the finite-length Warburg (FLW) impedance and the dynamic potential response of the FLW impedance in the time-domain has been developed in this study. Parameters reported in the literature estimated from experimental measurements carried out in polymer electrolyte fuel cells (PEFCs) have been considered to validate the new analytical transfer function. The analytical transfer function representing the FLW impedance can be considered in different equivalent electrical circuit configurations to simulate a more accurate dynamic output voltage of an electrochemical power system under the effect of diffusion phenomena. A Simulink model based on the Randles circuit and the new transfer function representing the FLW impedance is constructed to simulate the dynamic output voltage of a PEFC during a current-interrupt incident. In addition, a Simulink model based on an electrical circuit configuration and the new transfer function representing the FLW impedance is constructed to simulate the dynamic output voltage of a Li-ion battery. This study establishes a wider scope to relate the electrochemical impedance spectroscopy to the dynamic output voltage response of electrochemical power systems.