Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety perfo...Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be explored.This work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration modes.Two penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also established.The results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway events.The difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the pinhole.By controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.展开更多
研究锂离子动力电池热失控特性,获取关键参数,对热失控预警、热失控扩散阻止以及热失控扩散防护设计具有重要意义。本工作利用以镍钴锰酸锂[Li(Ni0.8Mn0.1Co0.1)O2,NCM811]为正极活性物质,分别以硅基材料(SiOx/graphite)和石墨(graphite...研究锂离子动力电池热失控特性,获取关键参数,对热失控预警、热失控扩散阻止以及热失控扩散防护设计具有重要意义。本工作利用以镍钴锰酸锂[Li(Ni0.8Mn0.1Co0.1)O2,NCM811]为正极活性物质,分别以硅基材料(SiOx/graphite)和石墨(graphite)为负极活性物质的25 A·h软包动力电池,开展了不同SOC(state of charge,荷电状态)针刺热失控特性研究,阐述了热失控过程现象与温度及电压的对应变化关系;通过钢针温度估算了不同SOC下单位容量热失控放热量,并对热失控喷射的火焰、喷射出去的高温固体物质等形式热传递进行分析。结果显示,在同等SOC时,硅基负极体系电池产生了更为剧烈的热失控。SOC为25%时,硅基负极体系电池在针刺过程中依然会发生剧烈的热失控,而石墨负极实验现象则较为温和。硅基负极体系电池荷电状态为100%、50%、25%时,电池周边都监测到持续一定时间的高风险温度,容易诱发临近电池产生热失控。电池针刺实验失重量随着SOC的增加而增加,100%SOC的硅基负极体系电池失重比例最高,达到了75.2%。展开更多
基金supported by the National Key R&D Program of China(2021YFB2402001)the China National Postdoctoral Program for Innovative Talents(BX20220286)+1 种基金the China Postdoctoral Science Foundation(2022T150615)supported by the Youth Innovation Promotion Association CAS(Y201768)。
文摘Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be explored.This work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration modes.Two penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also established.The results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway events.The difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the pinhole.By controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.
文摘研究锂离子动力电池热失控特性,获取关键参数,对热失控预警、热失控扩散阻止以及热失控扩散防护设计具有重要意义。本工作利用以镍钴锰酸锂[Li(Ni0.8Mn0.1Co0.1)O2,NCM811]为正极活性物质,分别以硅基材料(SiOx/graphite)和石墨(graphite)为负极活性物质的25 A·h软包动力电池,开展了不同SOC(state of charge,荷电状态)针刺热失控特性研究,阐述了热失控过程现象与温度及电压的对应变化关系;通过钢针温度估算了不同SOC下单位容量热失控放热量,并对热失控喷射的火焰、喷射出去的高温固体物质等形式热传递进行分析。结果显示,在同等SOC时,硅基负极体系电池产生了更为剧烈的热失控。SOC为25%时,硅基负极体系电池在针刺过程中依然会发生剧烈的热失控,而石墨负极实验现象则较为温和。硅基负极体系电池荷电状态为100%、50%、25%时,电池周边都监测到持续一定时间的高风险温度,容易诱发临近电池产生热失控。电池针刺实验失重量随着SOC的增加而增加,100%SOC的硅基负极体系电池失重比例最高,达到了75.2%。
