Effects of heating film and phase change material on preheating performance of the lithium-ion battery pack with large capacity under low temperature environment

In this work, a preheating management system for large-capacity ternary lithium battery is designed, where a novel coupling preheating method of heating film and phase change material (PCM) is employed to preheat. In order to make the preheating system meet the preheating requirements of the battery pack, effects of four influencing factors (heating film power, heating film power difference, cell spacing and PCM thickness) on preheating of the battery pack are studied numerically. Then, the relationship between four factors and preheating time and temperature difference is found, and the optimum parameters in the coupled preheating management system are obtained based on simulation. Finally, the preheating schemes of conventional preheating and rapid preheating under low ambient temperature are determined and investigated. The results show that rapid preheating takes much less preheating time than conventional preheating, where the temperature difference is about 1.48 K and the time consumption is 602 s, 518 s and 394 s under the low temperatures of 253.15 K, 263.15 K and 273.15 K, respectively. In addition, this preheating scheme also prove the feasibility of the designed battery pack thermal management system, which can meet the actual use of electric vehicles.