Construction of electrochemical model for high C-rate conditions in lithium-ion battery based on experimental analogy method

Abstract

Lithium-ion batteries (LIBs) modeling is critical for the safe and efficient operation of electric vehicles (EVs) and energy storage systems (BESSs). Most electrochemical models are mainly suitable for normal temperature or low C-rate conditions (≤2 C). Meanwhile, the electrochemical model parameters are usually obtained by the half-cell testing method. This method has difficulty in disassembling batteries and obtaining model parameters quickly. To solve this problem, the internal electrochemical behavior of LIBs under high-C rate conditions is first studied in this paper. Through the above theoretical analysis, the relationship between the solid phase diffusion coefficient, the reaction rate constant and temperature/concentration must be considered under high C-rate conditions. Then a fast calibration method for electrochemical model parameters is proposed, and a variable parameter high C-rate model is established. Finally, the variable parameter high C-rate model is validated at different rates of 5 °C, 25 °C and 55 °C. The results show that the mean absolute errors (MAE) of the variable parameter high C-rate model are within 13 mV under low C-rate conditions. Under the high C-rate condition (≤6 C), the MAEs of the model are within 50 mV.