New method for acquisition of impedance spectra from charge/discharge curves of lithium-ion batteries

A new analytical method is proposed to acquire the electrochemical impedance spectra of lithium-ion batteries(LIBs) from charge/discharge curves. From the voltage response to the current step during a charging or discharging process, the three elements are firstly calculated to construct the equivalent circuit model (ECM), i.e. the stray inductance, the Ohmic resistance and the distribution of relaxation timescales (DRT) spectrum of the LIB. Then the constructed ECM is utilized to analyze the impedance spectrum. Though the experimental setup is simple, it is observed that the impedance spectra of the LIB determined by the proposed method agree well with that measured using the conventional electrochemical impedance spectroscopy (EIS) method. Besides, the proposed method has the capability to obtain the Ohmic resistance and charge transfer resistance of LIBs in as short time as 0.05s, which makes the fast examination in the manufacturing factories, the internal temperature monitoring and online states estimation in the battery management system (BMS) possible.