A health-aware AC heating strategy with lithium plating criterion for batteries at low temperatures

Lithium-ion batteries are crucial power sources in many industries. When they are used at low temperatures, their performance decreases greatly. Thus, heating is required. This paper proposes a health-aware heating strategy based on the AC current. The strategy combines the use of the electro-thermal model for predicting the temperature increment in the battery caused by the AC current and a diagnostic method for lithium plating based on the charging transfer impedance. To obtain an accurate electro-thermal model for AC heating, various equivalent circuit models (ECMs) are tested at pulses with different frequencies and amplitudes, and the second-order ECM with a constant phase element (CPE) is found to obtain the smallest error. Then, the model and the lithium plating criterion are used to establish the boundary map of the lithium plating and voltage limitations. Based on the map, the optimal AC frequency and amplitude are selected for the heating strategy. Finally, an AC heating experiment is implemented to verify the strategy. The results show that the strategy not only increases the battery temperature at a maximum rate of 5.25 degrees C/min, but also achieves a capacity decrease of 0.3% in 80 heating cycles. Moreover, according to the battery disassembly results, there is no lithium plating on the electrode. These results prove that the proposed heating strategy can prevent lithium plating and achieve a high heating efficiency.