Impedance analysis of a lithium-ion battery using the electrochemical impedance spectroscopy

This paper analyzes the lithium-ion (Li-ion) batteries impedance using electrochemical impedance spectroscopy (EIS) technique. Firstly, the influence of the temperature, state of charge (SOC) and number of charging/discharging cycles on the impedance spectrum was studied. Nyquist graphs were used to perform this analysis. Subsequently, an equivalent electrical model was used to characterize the battery behavior under study at different operating conditions. Specifically, the model parameters were estimated using a non-linear least square method, allowing the consequent estimation of the impedance spectra obtained by the EIS technique. The experimental study included three temperature levels, five SOCs and different number of charging/discharging cycles. The results showed that the impedance depends considerably on the factors under consideration. Furthermore, the model used accurately estimated different impedance spectra.