Fast Characterization of Lithium-Ion Battery Impedance and Nonlinearity Using Optimized Multisine Perturbation Signal

Battery impedance and nonlinearity yield critical insights into dynamic response and electrochemical behavior, which are advantageous for state estimation and degradation diagnostics. However, the characterization method, which can simultaneously provide these two coupled indicators, has yet to be efficiently implemented. In this study, a novel fast characterization method for capturing battery impedance and nonlinearity, which is based on an odd multisine signal with optimized phase configuration, is proposed. A model-based comparative study across four broadband perturbation signals is undertaken to assess the viability of the proposed multisine signal in battery characterization. Furthermore, experimental investigations are conducted on the three-electrode experimental and commercial cylindrical cells to validate the efficacy and reproducibility of the proposed method. The findings demonstrate that the proposed optimized multisine signal, which features a crest factor reduced by 62.4%, achieves an acceptable impedance measurement comparable to the labor-intensive electrochemical impedance spectroscopy, while efficiently capturing battery nonlinearity within a hundred seconds of testing. The SOC dependency of battery characterization indicates that the proposed method is applicable for onboard state estimation and degradation diagnostics through the usage of impedance and nonlinearity.