液冷式热管理对动力电池热失控阻隔性能

The effect of liquid-cooled thermal management on thermal runaway of power battery

锂离子动力电池作为新能源汽车的主流动力源,是由成百上千个单体电池串并后高度集成于有限空间内以提高电池系统的能量密度。然而,电池组内单体电池意外发生热失控时极易将热量迅速传递给周边电池,引起电池系统整体发生热失控,酿成事故,可见阻隔热失控蔓延对保障电池安全至关重要。本文基于蛇形波纹管液冷式热管理系统,以18650型动力电池组为研究对象,探讨对目标电池加热诱发其热失控时,采用冷却措施对电池组内热失控传播的有效性。结果表明,在未采取任何冷却措施的情况下,目标电池发生热失控后迅速蔓延至整个电池模组,导致整个模组发生热失控;而在相同滥用环境下,采用液冷措施的实验中,目标电池被加热后出现长达一个小时的温度平台,未发生热失控,通过增大加热功率加速其发生热失控后,周围电池均未发生热失控蔓延。这表明液冷式热管理系统能够及时带走电池反应产生的热量,从而延长了从电池材料开始发生放热副反应到热失控之间的时间,并减少热失控电池对周围电池传播的热量,避免了热蔓延的发生。

Lithium-ion power batteries are the primary power source of new energy vehicles.Hundreds of cells are placed together and highly integrated into a confined space to improve the energy density of the battery system of an electric vehicle.When thermal runaway(TR)occurs unexpectedly in a single battery pack,the heat is easily transferred to the surroundings rapidly,resulting in the TR of the entire battery system and causing severe results.Therefore,preventing thermal propagation is vital to ensure battery safety.In this paper,a multichannel liquid cooling system with a serpentine wavy configuration is utilized for cooling a 18650 type lithium-ion battery pack.Furthermore,we explore the effectiveness of cooling measures on TR propagation in the battery pack when the target battery is triggered by heat.The results show that the TR of the target battery rapidly propagates toward the whole battery module without cooling measures.However,a temperature platform appears in the target battery approximately one hour after it is heated,and the target battery with liquid cooling measures does not experience TR in the same thermal abuse situation.Increasing the heating power to accelerate the progress of TR of the target battery prevents the surrounding batteries from being triggered when TR occurs in the target battery.Compared to the case without cooling measures,the cooling water of the management system can timely dissipate the heat generated by the battery reaction,resulting in the prolongation of the time between the exothermic side reaction of the battery material and TR.As a result,this reduces the heat transfer from the triggered battery to the neighbor batteries,thereby avoiding thermal propagation.