A Stitching Algorithm to Identify Wide-Bandwidth Electrochemical Impedance Spectra for Li-Ion Batteries Using Binary Perturbations

Abstract

A battery’s electrochemical impedance response provides great insight about its internal electrochemical dynamics and state-of-health. This paper presents a method to efficiently obtain wide-bandwidth electrochemical impedance spectra using two-level (binary) perturbation sequences. In this study, a physically based battery model’s current-voltage response is captured with state-space models using system-identification methods. However, any single identified model is accurate only within a specific, limited frequency range. A stitching procedure combines several state-space models to establish a composite state-space model that is accurate over a wide frequency range. A validation study shows excellent agreement between the impedance of the stitched state-space model and the original physically based battery model. The approach is equally applicable to extracting electrochemical impedance spectra from simulation models as for experimental investigations. © 2018 The Electrochemical Society.