The Distribution of Relaxation Time for Variable Temperature Cycle Aging of Electric Vehicle Power Battery

Changes in the ambient temperature of batteries in the use of electric vehicles accelerate the aging and attenuation resulting in increased internal resistance and performance degradation. The in situ electrochemical impedance measurement method is an effective tool for detecting electrochemical reactions on multiple time scales inside the battery. In this paper, the relaxation time distribution method is used to investigate the electrochemical impedance of the battery to reveal the aging mechanism during the temperature changes. In order to solve the problem of low frequency resolution of existing impedance spectrum analysis methods, the quantity and actual impedance in electrochemical reaction process are effectively analyzed. Gaussian process regression and regularization are an efficient tool for obtaining the distribution of functions and the minimization parameter. It is proved that through the conversion analysis of the frequency domain impedance data, it is helpful to obtain the true state of the battery more accurately. It lays a theoretical foundation for the further research of battery fault diagnosis, state estimation, life prediction and other methods.