Abstract:
Battery state of health(SOH) is the key to ensure the safe and stable operation of the system, and inaccurate state of health estimation will affect the performance of the battery, and even lead to problems such as battery abuse. Electrochemical impedance spectroscopy has become a powerful tool for analyzing the performance of lithium-ion batteries because it reflects the internal electrochemical processes through the impedance characteristics of the battery in a wide frequency range, which contains a large amount of information about the aging of batteries. However, the traditional impedance spectroscopy testing method is time-consuming and costly.Therefore, to achieve the fine detection and rapid assessment of the health state of lithium-ion batteries, this paper focuses on the battery state of health estimation method based on electrochemical impedance spectroscopy reconstruction technology. Based on the inverse repetitive maximum length sequence design of multi-frequency current excitation signal,the rapid test of battery impedance spectroscopy is achieved.The impedance spectroscopy reconstruction is carried out by continuous wavelet transform, and the battery impedance information within the target frequency range is obtained, and the whole process consumes less than 4.5 min. An empirical model is established by the amplitude of reconstructed impedance of batteries with different aging states at special frequency points, and a rapid and accurate evaluation of the battery state of health is realized.