圆柱形锂离子电池在针刺条件下的安全性研究

Study on the safety of cylindrical lithium-ion batteries under nail penetration conditions

动力电池受到尖锐物体挤压是汽车碰撞引发的主要损伤形式,也是一种十分严峻的工况,严重时锂离子电池会发生燃爆导致电动车损毁甚至是人身伤害。为了揭示锂离子电池在针刺工况下的安全性能,本工作采用自制搭建的针刺实验平台为基础,利用直径5 mm的平头钨钢针刺入18650圆柱形锂离子电池,讨论了4个参数(荷电状态、针刺速度、针刺深度和针刺位置)对锂离子电池安全性能的影响,利用红外摄像仪观测锂离子电池热失控现象,并记录锂离子电池在实验前后的温度、开路电压和载荷等表征数据。实验结果表明,锂离子电池在针刺工况下表现出明显的演变规律。锂离子电池在针刺失效后,并不会立即发生热失控,而是存在一定的反应时间;荷电状态越高,针刺深度越深,锂离子电池越容易发生热失控且与热失控剧烈程度成正相关;越靠近锂离子电池正负极两端,反应越剧烈;针刺速度与是否发生热失控没有明显的相关性。最后根据实验结果,为锂离子电池包的运输、安全使用和早期预警算法设计提供了建议。

Sharp object intrusion,particularly during automobile collisions,represents a significant risk to power batteries,potentially causing serious damage including ignition or explosion of lithium-ion batteries.This can lead to catastrophic outcomes for electric vehicles and pose risks to personal safety.This study aims to elucidate the safety performance of lithium-ion batteries under nail penetration conditions.Utilizing a custom-built experimental platform,we examined the effects of four parameters on battery safety:state of charge,penetration speed,penetration depth,and penetration location.Cylindrical 18650 lithium-ion batteries were subjected to penetration tests using a 5 mm diameter flat tungsten steel nail.The thermal runaway phenomenon was monitored using an infrared camera,and data such as temperature,open-circuit voltage,and load were recorded before and after the tests.Our findings indicate a clear pattern in the batteries'response to nail penetration;they do not immediately undergo thermal runaway but exhibit a delayed reaction.Factors such as higher states of charge and greater penetration depths significantly increase the likelihood of thermal runaway,which is also more severe when penetration occurs closer to the battery's positive and negative terminals.However,the speed of penetration does not have a significant correlation with the occurrence of thermal runaway.Based on these results,we offer recommendations for the transport,safe usage,and early warning algorithm design of lithiumion battery packs.