石墨-石蜡复合相变材料的圆柱型动力电池组热管理性能

Thermal management performance of cylindrical power batteries made of graphite paraffin composite phase change materials

本工作以21700容量型NCM811锂离子动力电池为研究对象,设计了正六边形布置的电池模组,外覆圆柱型石墨-石蜡复合相变材料的结构。利用数值模拟方法探究了不同恒定倍率放电,以及相邻两电池不同间距对模组热特性的影响。结果表明,对于不同倍率,相邻电池间距对电池模组高倍率放电过程中的温度影响要远大于低倍率放电过程,而对于相同倍率,小间距模组从放电开始至结束的温升要高于中间距和大间距模组。电池温度的变化相对于热流量在时间上有一定滞后,通过监测热流量的数值,能够对电池热管理的失效做出提前预知,提高电池组的安全性。

A hexagonal cell module was designed based on the 21700 capacity NCM811 lithium-ion cell,and a cylindrical structure of graphite paraffin composite phase change material was used to cover the battery.The thermal characteristics of the module was investigated using numerical simulations by varying the discharge rate and distance between two adjacent batteries.The results show that the distance between adjacent batteries has a greater influence on the battery temperature for a high rate discharge process compared to a low rate discharge process.At a fixed discharge rate,the temperature rise of the small distance battery modules is higher than that of the middle distance and large distance battery modules.The change of battery temperature lags behind the thermal flow in time.By monitoring the thermal flow,the failure of battery thermal management can be predicted in advance to improve the safety of batteries.