全气候自热锂离子电池及低温极速加热策略研究

The performance and available capacity of lithium-ion batteries deteriorate rapidly at low temperature, which seriously restricts the popularization application of new energy vehicles in cold areas. Therefore, low-temperature heating has become a feasible measure to improve the adaptability of batteries in low-temperature environment. Based on the 18650 cylindrical battery structure, a new type of all-climate self-heating lithium-ion battery is designed. With the core shaft as the heating element, it achieves extreme temperature rise from inside to outside at low temperature by means of electric trigger heating method. The experiments show that the self-heating battery can charge and discharge normally, and the core shaft as the heating element is effective. The electrochemical-thermal coupling model of self-heating lithium-ion battery is established, in which the traditional electrochemical model is modified to match the working characteristics of the self-heating battery. The distribution and variation of internal temperature of the self-heating battery during heating process is investigated, and the results show that the heating method reduces the hysteresis of the surface temperature rise of the battery. NSGA-II (Non-dominated sorting genetic algorithm Ⅱ) is used to establish a multi-objective optimization framework with heating rate and energy consumption rate as optimization objectives, and the optimal heating strategy is obtained, namely 33.80 mΩ protection resistance and 55.16% duty ratio. Simulation results show that the heating rate can reach 25.53 ℃/min, while the energy consumption rate is only 6.27%.