Study Of Temperature Effects On Lithium-ion Battery Performance With The Complex-parametered Equivalent Circuit Model

Development of new energy vehicles promotes the transformation and upgrading of the automobile industry.And it also promotes green development and cultivate new economic growth.With promotion of national policies,new energy vehicles industries have achieved great development.It is reported that China's new energy vehicle sales ranks first in the world for three consecutive years from 2016 to 2018.However,the new energy vehicle sale is highly dependent on national policies.The key technologies in new energy vehicles still need to be improved.the battery management system?BMS?is one of the key technologies in the new energy vehicles.It provides monitoring,diagnosis and protection functions,which ensure battery performance and safety.Therefore,a precise battery model is the basis of BMS management.Electrochemical Impedance Spectroscopy?EIS?battery model is one kind of equivalent circuit model.The structure is relatively simple and easy to understand.The modelling is based on the EIS tests and the battery chemistry,which makes EIS models more precise.The EIS battery model used in this paper is called complex-parametered model,which simulates dynamic loss in the batteries.In the practical applications,the temperature fluctuations are inevitable,which seriously affect the battery performance.Therefore,the temperature effects on the battery performance are investigated in this paper.The EIS of LiFePO₄ battery under different temperatures are tested.And the test data are used to analyze temperature effects on model parameters.The results showed that the inductance in high frequency part of the EIS was not affected by the temperature.Parameters including the ohmic resistance,the charge-transfer resistance,the diffusion,and especially the double-layer capacitance vary with the temperature,.The above battery model parameters values were obtained by curve fitting of the EIS data.And they changed with the temperature.Mathematical functions between battery model parameters and the temperature were obtained and explained with electrochemical theories.