Preheating Performance by Heating Film for the Safe Application of Cylindrical Lithium-ion Battery at Low Temperature

The conductivity of the electrolyte and the kinetics of Li+ inside lithium-ion batteries (LIBs) will decrease at low temperatures, which may promote the formation of lithium dendrite. The growing of lithium dendrites will penetrate the separator, and cause the internal short circuits and thermal runaway of cells. Thus, battery preheating is essential to improve the safety of LIBs. To investigate the temperature changes of battery during discharging and preheating at low temperatures, the electro-thermal model and the preheating model of LIBs at low temperature are established and verified based on the second-order equivalent circuit model. The internal resistance of battery decreases with the increase of temperature. Moreover, a battery module with polyimide flexible heating film is proposed, and the heating films are arranged on both sides of the battery symmetrically. When the power of heating films is 1 W, 3 W, and 5 W, it takes 395 s, 190 s and 126 s to preheat the battery temperature from - 10 degrees C to 25 degrees C, respectively. Additionally, different heating powers can be arranged in the heating process to reduce the heating time and temperature difference of battery. The research in this study contributes to the preheating of LIBs in cold regions, and has certain reference value.