摘要
电容型锂离子电池因比功率大、循环寿命超长等天然优势逐渐成为新能源汽车的研究热点。其碰撞安全特性与热失控特性对新能源汽车的安全应用至关重要。以正极为镍钴锰酸锂@活性炭复合材料、负极为软碳/石墨复合材料体系的电容型18650锂离子电池进行平板径向压缩试验,研究了电池压缩过程中力-电-热响应与内阻-载荷的关联特征,利用工业计算机断层(Computed Tomography,CT)扫描技术分析了单体外壳失效应力、结构压溃应力与电池内部构件屈服极限的联系,构建了基于内外电子流向的电池压缩失效模型。结果表明:电池隔膜的屈曲弯折与层间断裂、电芯端部的结构化破坏是导致内短路发生的主要原因;电池压缩过程符合标准“四阶段”过程,内短路前期载荷骤增曲线符合标准二次函数关系,且载荷曲线具有较强的荷电状态依赖性,相关拟合数据(决定系数R^(2)大于99.95%)可为预测电池安全作为参考依据。
This study aimed to investigate the damage and severity of the runaway phenomenon induced by flat compression on capacitive 18650 lithium-ion batteries across different States of Charge(SOC).To achieve this,flat compression tests were conducted on capacitive lithium-ion batteries at five distinct SOC levels using an electronic universal testing machine.The study measured key parameters,including battery surface temperature,open-circuit voltage,and load throughout the compression process.Following each compression,industrial Computed Tomography(CT)scans were performed on the batteries to analyze the internal failure modes.Batteries at different States of Charges(SOCs)were disassembled to measure changes in electrode thickness,isolating the effects of internal pressure variations.The potential safety of battery reuse after each incremental 1 mm of compression was also evaluated.The results revealed that higher SOCs in the batteries corresponded to a more severe heat runaway phenomenon during flat compression.When the battery s SOC exceeded 60%,the peak temperature was observed on the positive electrode side.As the SOC increased,the thickness of the negative electrode also increased continuously,resulting in a higher peak load that ultimately led to battery failure.The compression process of the battery can be categorized into four distinct stages.As the compression depth increased,the internal voids of the battery were progressively compressed.At a depth of 7 mm,both the electrodes and separator fractured,resulting in numerous discharge paths that further intensified internal heat generation.During the third compression stage,the relationship between load and displacement displayed a standard quadratic function,with a fitting degree exceeding 99.95%.Prior to reaching a compression depth of 5 mm,the battery retained approximately 90%of its capacity,while the peak temperature during charging and discharging was around 40℃.Additionally,once the compression exceeded 6 mm,there was a significant increase in peak temperature during charging and discharging,accompanied by an extended duration at constant voltage during charging.This indicates that while the battery poses minimal safety risks under minor deformations,it presents substantial safety hazards with larger deformations(exceeding 7 mm).
作者
杨军
温浩伟
马宇哲
董晨晖
刘登锋
杨斌
阮殿波
乔志军
YANG Jun;WEN Haowei;MA Yuzhe;DONG Chenhui;LIU Dengfeng;YANG Bin;RUAN Dianbo;QIAO Zhijun(Faculty of Mechanical Engineering&Mechanics,Ningbo University,Ningbo 315211,Zhejiang,China;Hesheng Alternative Energy Technology Co.,Ltd.,Ningbo 315040,Zhejiang,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2024年第12期4685-4695,共11页
Journal of Safety and Environment
基金
浙江省科技计划项目(2022C01072)
宁波市科技计划项目(2022Z206)。
关键词
安全工程
锂离子电池
平板压缩试验
热失控
safety engineering
lithium ion battery
flat compression test
thermorunaway
