Thermal-electric modelling and multi-state joint parameter identification of lithium-ion batteries

Abstract This paper proposes a model for the characterization of thermal-electric properties of lithium-ion batteries. The model achieves high accuracy estimation of the temperature and voltage-current characteristics of the battery considering thermal electric coupling. A second-order equivalent circuit model and a lumped-parameters thermal model are developed to capture the electric and temperature characteristics of the cell separately. A polynomial product equation is proposed to capture the relationship between battery temperature and state of charge for the purpose of describing the interactions of thermal and electric parameters during the charging/discharging processes. Experimental data of an NCR18650B lithium-ion battery cell are gathered in laboratory tests and used for parameter estimation of the model built in the paper. Compared with the existing thermal-electric coupling models that rely on a look-up table, the model proposed achieves better accuracy in terms of temperature and voltage-current characteristics estimation.