Developing an electro-thermal model to determine heat generation and thermal properties in a lithium-ion battery

Lithium-ion batteries should continuously be operated at the optimum temperature range \(\left( {15 \sim 40 \,^\circ C} \right)\) for the best performance. Surface temperature monitoring is critical for the safe and efficient operation of the battery. In this study, initially, the electrical parameters of the battery are determined by applying a second-order equivalent circuit model. This model then is integrated with a thermal model based on the temperature dependent behavior of the electrical parameters and the heat generated. The input parameters to the electro-thermal model include the current, the ambient fluid temperature and the output parameters include the terminal voltage, state of charge, cell core temperature and cell surface temperature. In this research, the entropic coefficient and battery thermal parameters have been taken into consideration concurrently, which will lead to both saving plenty of time and cost compared to other methods. The accuracy of the suggested analytical approach for estimating the surface temperature and the amount of heat generation is validated with the pulse-rest tests of an 18,650 cylindrical lithium-ion battery with a nominal capacity of 2600 mAh at three different ambient temperatures and three charge/discharge current rates. The comparison of results indicate that the maximum error of the proposed algorithm is about 0.6 K under a wide range of test conditions.