Abstract: Lithium-ion batteries are widely used in electric vehicles due to their high energy density, long cycle life, and excellent stability. However, the significant heat generation caused by power fluctuations under dynamic driving conditions poses substantial challenges to the safety and longevity of the battery. These temperature variations, especially during rapid acceleration or deceleration, can accelerate battery degradation and even thermal runaway. Most existing research focuses on the thermal behavior of batteries under fixed ambient temperatures or constant discharge rates, which fail to fully replicate the diverse and fluctuating conditions that batteries experience in real-world dynamic operations. To address this gap, this study investigates the thermal performance of a battery pack under three typical dynamic operating conditions: steady operation, alternating load operation, and progressive acceleration operations. The experimental results show that at an ambient temperature of 35℃, the direct cooling thermal management system meets the temperature control requirements during steady operation and alternating load operation. However, under progressive acceleration operations, the battery pack's maximum surface temperature reaches 49.8℃, accompanied by a significant temperature difference of 16.5℃, both of which pose risks to battery safety and performance. After the installation of fins, the maximum temperature is reduced to 40.9℃, and the temperature difference drops to 5.0℃. The longitudinal temperature difference decreases from 11.2℃ to 4.6℃, and the transverse temperature difference decreases from 5.9℃ to 1.2℃. The addition of fins not only enhances longitudinal heat conduction but also helpes mitigate the transverse temperature imbalance. These findings underscore the importance of optimizing thermal management strategies. This study provides valuable experimental data to guide the development of more effective thermal management systems for lithium-ion batteries in electric vehicles, ultimately contributing to improved battery safety and longevity under real-world driving conditions.

Key words: dynamic operating conditions, electric vehicles, direct cooling battery thermal management system, homogeneity, fins

摘要： 锂离子电池因其高能量密度、长寿命和高稳定性而广泛应用于电动汽车。但其在动态工况下因功率波动导致的发热激增，对电池安全性和寿命构成挑战，尤其是在连续变速中可能导致电池老化，甚至引发热失控。现有研究多聚焦于固定环境温度或单一放电倍率下的热行为评估，难以反映实际复杂情况。本研究测试了三种典型动态工况(匀速运行、交替变载运行和连续加速工况)下的温控效能。结果表明，在35℃环境下，直冷电池热管理系统能够满足匀速运行和交替变载工况下电池组的温控要求；但连续加速工况下电池组表面的最高温度高达49.8℃，温差达16.5℃。增设翅片后电池组最高温度和温差分别降至40.9和5.0℃，纵向温差从11.2℃减小至4.6℃，横向温差由5.9℃降低至1.2℃。翅片不仅利于解决纵向导热不佳问题，而且一定程度缓解了电池组的横向温度不均问题。本研究可为开发直冷热管理系统提供实验依据。

关键词: 动态工况, 电动汽车, 直冷电池热管理系统, 均温性, 翅片