高镍层状氧化物正极晶界热失效的原位电镜研究

高镍层状氧化物正极晶界热失效的原位电镜研究

李欣岩，高  昂，张庆华，谷  林^*

(中国科学院物理研究所，北京 100190)

摘  要 高镍层状氧化物正极材料的热失控现象是制约锂离子电池发展的重大安全隐患，然而目前针对高镍材料热稳定性的研究普遍缺乏原子尺度的探究。本文以LiNiO₂（LNO）为研究对象，通过原位透射电镜动态地观察了在原子尺度下LNO晶界处的热失效过程。在LNO扭转晶界处的热失效过程主要表现为延晶界层的活性物质损失以及Li/Ni反位逐渐增多所伴随的层状→类尖晶石→岩盐的逐步相变。本实验提出了高镍正极晶界处热失效的原子尺度机制，并对设计高热稳定性的锂离子电池层状氧化物正极材料具有借鉴意义。

关键词 原位透射电子显微学；原位加热；高镍正极；热稳定性

中图分类号：O766⁺.1；O77⁺1；TB34；TG115.21⁺5.3 

文献标识码：A doi:10.3969/j.issn.1000-6281.2021.05.004

In situ TEM research on thermal failure of grain boundary in Ni-rich layered oxide cathodes

Li Xin-yan，Gao Ang，ZHANG Qing-hua，GU Lin*

(Institute of Physics, Chinese Academy of Sciences, Beijing 100190，China)

Abstract   Thermal runaway of Ni-rich layered oxide cathode materials is an intrinsic safety hazard limiting the development of lithium-ion batteries, yet current research on the thermal stability of Ni-rich materials lacks the investigation of atomic-scale mechanisms. Herein, the atomic-scale thermal failure process at grain boundaries of LiNiO₂ (LNO) is dynamically observed by in situ transmission electron microscopy. The thermal failure process at twist boundary of LNO consists of the loss of active material along the twist boundary layer and the gradual phase transition of layer → spinel-like → rocksalt accompanied with the increase of Li/Ni antisites. We propose an atomic-scale mechanism of thermal failure at the grain boundary of Ni-rich cathode and provide a solution for the design of layered oxide cathode materials with high thermal stability for Li-ion batteries.

Keywords  in situ TEM; in situ heating; Ni-rich cathode; thermal stability

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