Fast Charging Control of Lithium-ion Batteries Based on Electrochemical- thermal Coupling Model

The existing electrochemical mechanism models of lithium-ion batteries do not consider the coupling relationship between heat generation and chemical reactions in the fast charging control process. As a result, the model cannot accurately describe the internal reaction and state of the battery. In order to further enhance the predictive ability of the model, it is necessary to couple the heat generation model on the basis of isothermal model. Therefore, a fast charging control model based on electrochemical-thermal coupling is proposed in this paper. Firstly, the parameters of electrochemical-thermal coupling model are classified, various parameter acquisition methods are analyzed, and accurate measurement and parameter identification are performed. The model is built, with its accuracy verified. The results show that the results of terminal voltage, cathode potential and temperature output from the model achieve high accuracy under different thermal conditions, meaning the model is suitable for fast charging simulation in a wide range of temperature. Meanwhile, sensitivity analysis is carried out on the reaction rate constant and ambient temperature parameters in the model. Then, a fast charging control simulation is conducted on the model with PID controller, the charging current is adjusted real-time according to the estimated cathode potential, achieving fast charging current simulation without lithium plating in a wide range of temperature. Finally, the results of model simulation and the comparative verification of constant-current charging indicate that the fast charging strategy proposed enables fast charging of the battery while avoiding the side reaction of lithium deposition. © 2022, Society of Automotive Engineers of China. All right reserved.