锂离子软包电池漏液对电性能、安全性影响及大数据预警应用

Study on the Influence of Lithium Ion Soft Package Battery Leakage on Electrical Performance and Safety,and Big Data Warning

随着新能源车辆市场保有量增多和动力电池能量密度提升,热失控事件逐渐增多,动力电池安全问题变得尤为重要,漏液是诱发电池热失控的关键因素之一。本文通过模拟电芯级和更接近整车应用的模块级漏液,研究漏液对电性能和安全性的影响;同时,基于实验数据及整车大数据提取漏液电池特征,建立预警逻辑,实现漏液预警大数据监控。针对电芯级实验,对比分析循环和静置状态下漏液电芯与正常电芯的测试数据,发现漏液电芯与正常电芯相比,质量减少、厚度增加、容量衰减、直流内阻增大、电芯拆解及表征后存在异常,证明了漏液对电性能及安全性具有一定影响。针对模块级实验,通过分析模块中不同漏液程度并联单元的厚度、直流内阻等变化特征,证明了厚度和直流内阻都随着漏液程度的增大而变大,也增大了电池潜在的安全风险。针对整车级大数据,识别漏液电池在充电起始及结束阶段的压差特征,建立预警识别逻辑,并进行大数据监控。

With the increase of new energy vehicles in the market and battery energy density,thermal runaway events gradually increase.Battery safety issues become particularly important,whereas leakage is one of the key factors inducing battery thermal runaway.In this paper,the influence of leakage on electrical performance and safety is studied by simulating leakage at the cells and modules.At the same time,based on experimental data and remote vehicle data,the characteristics of the leaked battery are extracted and the warning logic is established to achieve online monitoring of the leakage warning.For cells test,a comparative analysis is conducted on the test data of leaking and normal battery cells under cyclic and static states.It is found that compared with normal cells,leaking cells show mass reduction,thickness increase,capacity fade,DC internal resistance increase and dismantling characterization abnormity,which proves that leakage has certain impact on the electrical performance and safety.For module test,characteristics of the thickness and DC internal resistance changes from the parallel units with different leakage degrees are studied.It proves that the thickness and DC internal resistance increase with the increase of leakage degrees,which also augments the potential safety risk of the battery.For vehicle level big data,the pressure difference characteristics of the leaked battery during the starting and ending stages of charge are identified to establish warning and identification logic and conduct online monitoring.