Fast State of Charge Estimation for Lithium-ion Battery Based on Electrochemical Impedance Spectroscopy Frequency Feature Extraction

A fast SOC estimation method based on electrochemical impedance spectroscopy (EIS) dataset combined with a simplified electrochemical model is proposed in this paper. Firstly, the solution-phase lithium-ion diffusion model is stripped from the simplified electrochemical model to characterize the lithium-ion concentration change. Then, the key frequency feature for SOC estimation is extracted based on the correlation analysis between the solution-phase lithium-ion concentration and the EIS data. Finally, the proposed SOC estimation method is expanded to consider the influences of ambient temperature. Experimental study indicates that the integration of lithium-ion diffusion can significantly improve the accuracy and reduce the computational time compared with the traditional broadband domain method and the fractional order equivalent circuit model (FOECM).