An electrochemical-thermal coupling model based on two-factor parameter modification for Li-ion battery

Abstract

The accurate establishment of battery model can improve the design reliability and reduce the design risk, which provides an important basis for the research of battery. Firstly, the key parameters of the Li-ion battery model were identified by the least square method based on the full-cell equivalent circuit model of single-particle impedance spectrum, and the diffusion coefficient and exchange current density under different temperature and SOC conditions were calculated. At the same time, the one-dimension thermal rate model is used as the heat source of the three-dimensional model, and the mean temperature T of the three-dimensional model is calculated by using Fourier's law, and T is fed back to the one-dimensional model as the key parameter to modify the conductivity, diffusion coefficient and exchange current density, and a semi-empirical electrochemical-thermal coupling model with two-factor parameter modification is established. Finally, the model is verified by the temperature field distribution and discharge voltage curve at different discharge rates. The maximum temperature difference is less than 3.1 °C, and the maximum voltage difference error is less than 0.131V. The results show that the improved model can accurately reflect the influence of temperature on the model parameters, and has high accuracy in the estimation of battery terminal voltage and SOC.