An impedance-based electro-thermal model integrated with in-situ lithium-plating criterion for AC heating at low temperatures

AC-based preheating is a promising method to realize extremely quick temperature rise of lithium-ion batteries and improve their performance at low temperatures. There are two core issues for this method. One is the accurate calculation of battery parameters during heating, and the other is the prediction of lithium-plating. In this paper, an impedance-based thermal model is proposed and coupled with the second-order R-CPE model to predict battery electrical and thermal parameters during AC heating. Based on the charge transfer voltage calculated by the battery model, an in-situ lithium plating criterion is proposed. With the consideration of the AC frequency and process in which the charge goes through the SEI film, the proposed electro-thermal model can accurately predict the evolution of battery parameters during heating and its error is lower than popular equivalent circuit models such as second-order RC, first-order R-CPE and first-order RC model. Under the test conditions with AC of constant frequency and altitude, the error for the terminal voltage reached by the proposed battery model is below 44 mV and that for the temperature is smaller than 0.65 °C. When it is applied to the AC heating strategy with variable frequency and altitude, the maximum errors are 159.71 mV for the voltage and 1.03 °C for the temperature. Moreover, to verify the lithium-plating criterion, heating cycling experiment is performed. According to the test results of capacity, anode appearance, SEM and EDS for the battery, the proposed criterion can accurately predict the lithium plating in the battery.