An electrochemical–thermal model of lithium-ion battery and state of health estimation

The performance of lithium-ion batteries deteriorates with the passage of time, estimating State-of-Health of batteries correctly is important. In this paper, an electrochemical-thermal model including the electric double layer model is developed. In the frequency domain, sensitivity analysis of the electrochemical processes during battery aging are carried out based on electrochemical impedance spectroscopy and distribution of relaxation time method. In the time domain, single parameter sensitivity analyses are performed. Methods of obtaining different types of parameters in the model are studied, and the electrochemical parameter values of the battery under different cycles are obtained. Finally, some key parameters with higher correlation with State-of-Health are selected to achieve State-of-Health estimation of the battery.