Electrochemical model of lithium-ion battery for wide frequency range applications

The electrochemical model is widely studied because of its capability to accurately describe various reactions inside the lithium-ion battery. In this paper, the impedance from 10 mHz to 1 kHz of the Pseudo 2-Dimensional (P2D) model is analyzed, and it is found that the impedance characteristics of the P2D model only at low frequencies (below 0.5 Hz) are consistent with those of actual batteries. In order to improve the applicability of the electrochemical model, a model with good simulation accuracy under the excitation of 10 mHz to 1 kHz is established, by combining the P2D model with the theory of the double layer (DL) and the solid electrolyte interphase (SEI). In the frequency domain, the new model is decoupled, the separate impedance characteristic of each component described by the model is analyzed, and the contribution of each component to the total impedance characteristics at each frequency band is analyzed and described in detail. Meanwhile, the impedance of the new model under the excitation of 10 mHz to 1 kHz is compared with the EIS data of the actual lithium-ion batteries to verify the simulation accuracy of the impedance of the new model under all frequencies. In the time domain, the responses of the new model and the P2D model at different conditions are compared with measured datas, and the results shows that the new model is superior to the P2D model under high-frequency excitation and has good simulation accuracy over a wide frequency range (10 mHz-1 kHz). (C) 2020 Elsevier Ltd. All rights reserved.