Thermal Performance of Reverse‐Layered Air‐Cooled Cylindrical Lithium Battery Pack Integrated with Staggered Battery Arrangement and Spoiler

Abstract

In recent years, with the influence of the current energy shortage and massive environmental pollution, the development of new energy electric vehicles has become a global focus. Lithiumion battery pack is one of the vital components of electric vehicles (EVs). Compared with other types of battery, with the advantages of high energy density, low self-discharge, and long cycle life, lithium-ion battery is extensively used in electric vehicles. [1][2][3][4] However, there is a phenomenon of heat accumulation in the process of the charge and discharge of lithium-ion batteries. The accumulated heat will have a significant impact on the performance and safety of the module of the battery pack, so it is necessary to take appropriate cooling measures. [5,6] Generally, the temperature range that lithium-ion batteries can work effectively is 10-50 C, and the maximum temperature difference of the battery module ought to be controlled within 5 C. To make the battery have a better working environment, the operating temperature of the battery pack ought to be limited between 20 and 40 C. [7,8] Consequently, to ensure it works in a suitable temperature environment, the design of a battery thermal management system is particularly important.At present, the common battery thermal management strategies include liquid cooling, [9,10] air cooling, [11,12] phase change materials (PCM) cooling, [13,14] heat pipe cooling, [15,16] hybrid cooling, [17,18] etc. Compared with other battery thermal management strategies, the air cooling system has been widely used on account of its advantages of lightweight, simple structure, and low cost. [19] However, in the existing air-cooled system, large temperature difference often occurs inside the battery pack. Therefore, for enhancing the heat dissipation performance of air-cooled battery thermal management system (BTMS) and making the temperature distribution of the battery more uniform, scholars have done depth research on the structural design, battery arrangement, adding spoiler, and airflow control.In terms of structural design, Chen et al. [20] researched the symmetrical and asymmetrical air-cooled BTMS system, it was found that the symmetrical system had better heat dissipation performance than the asymmetrical system. And with a small number of batteries in BTMS, the temperature distribution of the batteries was more uniform. Liu et al. [21] proposed a new and original battery thermal management system of J-type, which had one more outlet than the traditional U-type and Z-type BTMS. With different operating conditions, the control valve was used to adjust the opening of the two outlets, which greatly improved the controllability and flexibility of battery thermal management. In terms of battery arrangement, Zhu et al. [22] considered three typical battery arrangements in the same battery module: equal arrangement, increasing arrangement, and decreasing arrangement. Then the study found that the temperature uniformity of the battery module in decreasing