加热引发三元18650型锂离子电池组的燃烧特性

Burning characteristics of the 18650-type lithium-ion ternary battery pack induced by heating

为研究动力锂电池组的燃烧特性,本工作以三元18650型锂离子电池组为研究对象,在受限空间中开展了加热引发电池组热失控实验,通过温度数据采集及高清摄像的方法,对不同受热位置和不同受热功率时的锂电池组的典型特征参数进行了试验研究,包括着火时间、火焰形态、临界热失控温度等,此外还开展了水雾灭火试验。结果表明:三元锂电池组热失控温度介于120~139℃,最大燃烧温度会随着热源功率的增大而增加,最高温度可达800℃。侧面过热时锂电池组燃烧剧烈程度会随着与热源距离的增加而减弱,出现多次断续复燃现象。相比侧面过热,锂电池组底面负极过热时燃烧程度更剧烈,电池会连续喷射燃烧,同时外部热源功率的增大会缩短着火时间并加剧燃烧强度。此时采用水雾对着火的锂电池组灭火,可以对燃烧中的锂电池组进行有效的抑火降温,使电池内部温度降低到临界温度以下,从而有效防止复燃。

In this study,the 18650-type lithium-ion ternary battery pack was selected as a research object to investigate the burning characteristics of power lithium battery packs.A series of experiments with thermal runaway induced by heating was conducted in a confined space.Some typical characteristic parameters were studied at various heating locations and varying power by measuring temperature data and recording a high-digital video,including the ignition time,flame shape,and critical temperature of thermal runaway.Besides,a fire extinguishing test with water mist was conducted to test the effect of fire suppression and cooling.Results demonstrated that the thermal runaway temperature was at 120—139℃for the lithium ternary battery pack.The maximum burning temperature increased with increased heating power,and peak value was up to 800℃.The burning intensity of the lithium battery weakened as spacing between the battery and heating source increased when the battery pack was heated from the side.In such cases,several intermittent reburning instances occurred.We observed that the burning intensity of the battery pack with bottom overheating was stronger than that with side overheating.Unlike in side overheating,the batteries were continuously burned by spraying in bottom overheating.Meanwhile,ignition time was reduced,and burning intensity was increased with increased external heat source power.Herein,the burning batteries were effectively suppressed and cooled using water mist.The main reason was that internal temperature in the battery pack was reduced below the critical value so that reburning was prevented effectively.However,we noted that secondary damage caused by water pollution and short-circuit discharge must be carefully considered according to fire suppression needs although water mist can be used as an effective fire-fighting method for lithium battery fire exhaustion.