溶解
材料科学
降级(电信)
阴极
电化学
同步加速器
透射电子显微镜
氧化物
化学工程
过渡金属
离子
扫描透射电子显微镜
分析化学(期刊)
纳米技术
冶金
化学
电极
光学
物理化学
催化作用
有机化学
电信
色谱法
工程类
物理
计算机科学
生物化学
作者
Bo Cao,Tianyi Li,Wenguang Zhao,Liang Yin,Hongbin Cao,Dong Chen,Luxi Li,Feng Pan,Ming‐Jian Zhang
出处
期刊:Small
[Wiley]
日期:2023-06-20
卷期号:19 (42)
被引量:8
标识
DOI:10.1002/smll.202301834
摘要
Understanding the mechanism of the rate-dependent electrochemical performance degradation in cathodes is crucial to developing fast charging/discharging cathodes for Li-ion batteries. Here, taking Li-rich layered oxide Li1.2 Ni0.13 Co0.13 Mn0.54 O2 as the model cathode, the mechanisms of performance degradation at low and high rates are comparatively investigated from two aspects, the transition metal (TM) dissolution and the structure change. Quantitative analyses combining spatial-resolved synchrotron X-ray fluorescence (XRF) imaging, synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques reveal that low-rate cycling leads to gradient TM dissolution and severe bulk structure degradation within the individual secondary particles, and especially the latter causes lots of microcracks within secondary particles, and becomes the main reason for the fast capacity and voltage decay. In contrast, high-rate cycling leads to more TM dissolution than low-rate cycling, which concentrates at the particle surface and directly induces the more severe surface structure degradation to the electrochemically inactive rock-salt phase, eventually causing a faster capacity and voltage decay than low-rate cycling. These findings highlight the protection of the surface structure for developing fast charging/discharging cathodes for Li-ion batteries.
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