Lithium-ion batteries suffer from a free-fall drop in available capacity and accelerated ageing under extremely cold climates. Therefore, they must be preheated before normal operations. Internal heating schemes using direct current (DC) or alternating current (AC) are more promising than traditional conductive and convective approaches owing to their superiorities in terms of high efficiency, rapid speed, and uniform temperature distribution. The internal heating method is popular in research, but whether it is suitable for modern battery cells is still an open question.
This work mainly aims to establish the general electro-thermal model for battery temperature prediction of internal heating under cold climates for different battery types. It can help implement internal heating techniques in real applications.
Traditional equivalent circuit models (ECMs) are lumped models suitable for battery management. At the same time, they are short for interpreting critical electrochemical states of cells during internal heating, especially in a lack of high-frequency information. To bridge this gap, full-frequency range electrochemical impedance spectroscopy (EIS) can help understand the inherent mechanism of ECMs related to electrochemical processes.
In this work, first, full-frequency range EIS is done, and enhanced ECMs based on EIS data are established for different types of cells. Then, battery internal heating tests using AC for cells are done. Next, a lumped thermal model based on the available thermal parameters is established. Finally, the combined electro-thermal model is validated for predicting battery surface temperature under cold climates.
With this general electro-thermal modelling method, the relationship between the internal heating under full frequency heating current and the battery temperature prediction for battery cells can be established.