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Direct Visualization of Li Dendrite Effect on LiCoO2 Cathode by In Situ TEM
Small ( IF 13.0 ) Pub Date : 2018-11-06 , DOI: 10.1002/smll.201803108 Zhenzhong Yang 1 , Phuong-Vu Ong 1 , Yang He 2 , Le Wang 1 , Mark E. Bowden 2 , Wu Xu 3 , Timothy C. Droubay 1 , Chongmin Wang 2 , Peter V. Sushko 1 , Yingge Du 1
Small ( IF 13.0 ) Pub Date : 2018-11-06 , DOI: 10.1002/smll.201803108 Zhenzhong Yang 1 , Phuong-Vu Ong 1 , Yang He 2 , Le Wang 1 , Mark E. Bowden 2 , Wu Xu 3 , Timothy C. Droubay 1 , Chongmin Wang 2 , Peter V. Sushko 1 , Yingge Du 1
Affiliation
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Nonuniform and highly localized Li dendrites are known to cause deleterious and, in many cases, catastrophic effects on the performance of rechargeable Li batteries. However, the mechanisms of cathode failures upon contact with Li metal are far from clear. In this study, using in situ transmission electron microscopy, the interaction of Li metal with well‐defined, epitaxial thin films of LiCoO2, the most widely used cathode material, is directly visualized at an atomic scale. It is shown that a spontaneous and prompt chemical reaction is triggered once Li contact is made, leading to expansion and pulverization of LiCoO2 and ending with the final reaction products of Li2O and Co metal. A topotactic phase transition is identified close to the reaction front, resulting in the formation of CoO as a metastable intermediate. Dynamic structural and chemical imaging, in combination with ab initio simulations, reveal that a high density of grain and antiphase boundaries is formed at the reaction front, which are critical for enabling the short‐range topotactic reactions and long‐range Li propagation. The fundamental insights are of general importance in mitigating Li dendrites related issues and guiding the design principle for more robust energy materials.
中文翻译：
原位TEM直接可视化锂枝晶对LiCoO2阴极的影响
锂的不均匀和高度局限性树突已知会在可充电锂电池的性能上造成有害的且在许多情况下造成灾难性影响。然而，与锂金属接触时阴极失效的机理尚不清楚。在这项研究中，使用原位透射电子显微镜，可以在原子尺度上直接观察到Li金属与LiCoO 2的定义明确的外延薄膜（最广泛使用的阴极材料）之间的相互作用。结果表明，一旦与Li接触，就会引发自发迅速的化学反应，导致LiCoO 2的膨胀和粉碎，最终以Li 2的最终反应产物结束。O和Co金属。在反应前沿附近发现了全能相变，导致形成了作为亚稳中间体的CoO。动态结构和化学成像与从头算起的模拟相结合，揭示了在反应前沿形成了高密度的晶粒和反相边界，这对于实现短程电位反应和长程Li传播至关重要。这些基本见解对于缓解锂树枝状晶体的相关问题以及指导设计更坚固的能源材料具有普遍意义。
更新日期：2018-11-06
中文翻译：
原位TEM直接可视化锂枝晶对LiCoO2阴极的影响
锂的不均匀和高度局限性树突已知会在可充电锂电池的性能上造成有害的且在许多情况下造成灾难性影响。然而，与锂金属接触时阴极失效的机理尚不清楚。在这项研究中，使用原位透射电子显微镜，可以在原子尺度上直接观察到Li金属与LiCoO 2的定义明确的外延薄膜（最广泛使用的阴极材料）之间的相互作用。结果表明，一旦与Li接触，就会引发自发迅速的化学反应，导致LiCoO 2的膨胀和粉碎，最终以Li 2的最终反应产物结束。O和Co金属。在反应前沿附近发现了全能相变，导致形成了作为亚稳中间体的CoO。动态结构和化学成像与从头算起的模拟相结合，揭示了在反应前沿形成了高密度的晶粒和反相边界，这对于实现短程电位反应和长程Li传播至关重要。这些基本见解对于缓解锂树枝状晶体的相关问题以及指导设计更坚固的能源材料具有普遍意义。
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