Battery safety is critical to the application of lithium-ion batteries, especially for high energy density battery applied in electric vehicles. In this paper, the thermal runaway mechanism of LiNi_0.8Co_0.1Mn_0.1O₂ based lithium-ion battery is illustrated. And the reaction between cathode and flammable electrolyte is proved as the trigger of the thermal runaway accident. In detail, with differential scanning calorimeter tests for battery components, the material combination contributing to thermal runaway was decoupled. Characterization with synchrotron X-ray diffraction and transmission electron microscopy with in-situ heating proved that the vigorous exothermic reaction is initiated by the liberated oxygen species. The pulse of highly active oxygen species reacted quickly with the electrolyte, accompanied with tremendous heat release, which accelerated the phase transformation of charged cathode. Also, the mechanism is verified by a confirmatory experiment when the highly active oxygen species were trapped by anion receptor, the phase transformation of the charged cathode was inhibited. Clarifying the thermal runaway mechanism of LiN_i0.8Co_0.1Mn_0.1 based lithium-ion battery may light the way to battery chemistries of both high energy density and high safety.

电池安全性对于锂离子电池的应用至关重要，特别是对于电动汽车中使用的高能量密度电池而言。本文阐述了LiNi _0.8 Co _0.1 Mn _0.1 O ₂基锂离子电池的热失控机理。阴极与易燃电解质之间的反应被证明是热失控事故的诱因。详细地，通过差示扫描量热仪对电池组件的测试，导致热失控的材料组合被解耦了​​。同步加速器X射线衍射和原位透射电子显微镜表征加热证明剧烈的放热反应是由释放的氧引发的。高活性氧的脉冲与电解质快速反应，并伴随大量的热释放，从而加速了带电阴极的相变。另外，通过高活性氧被阴离子受体捕获，抑制了带电阴极的相变，证实了该机理。_阐明基于LiN _i0.8 Co _0.1 Mn _0.1的锂离子电池的热失控机理，可能为高能量密度和高安全性的电池化学方法开辟道路。