Rapid Impedance Spectroscopy Reconstruction Based on M Sequence for SOH Estimation of Lithium-Ion Battery

The longer measurement time and high equipment cost of traditional electrochemical impedance spectroscopy (EIS) testing techniques make it difficult to be applied to engineering practice. To address the above issues, firstly, this paper proposes a rapid impedance spectroscopy testing method based on M sequence. Three sets of M sequences with different frequencies and orders are applied to the battery in turn as current excitation signals to get the corresponding voltage response signals, and then the impedance information of batteries at each frequency is obtained using the continuous wavelet transform algorithm, which greatly reduces test time. Secondly, according to the characteristics of the impedance spectroscopy of LiCoO2 batteries, a third-order fractional-order equivalent circuit model is established, and the impedance spectroscopy of each aging state is fitted to obtain the corresponding model parameters. After the correlation analysis of parameters, this paper builds a multiple linear regression equation between internal resistance parameters and state of health (SOH) for SOH estimation. Finally, it has been verified that the error of the proposed SOH estimation algorithm is within 0.3%.