材料科学
透射电子显微镜
离子
纳米颗粒
电化学
扫描透射电子显微镜
堆积
相(物质)
锂(药物)
阴极
结晶学
原子单位
分析化学(期刊)
电极
纳米技术
化学
物理化学
医学
物理
有机化学
量子力学
色谱法
内分泌学
作者
Xia Lu,Yang Sun,Zelang Jian,Xiaoqing He,Lin Gu,Yong‐Sheng Hu,Hong Li,Zhaoxiang Wang,Wen Chen,Xiaofeng Duan,Liquan Chen,Joachim Maier,Susumu Tsukimoto,Yuichi Ikuhara
出处
期刊:Nano Letters
[American Chemical Society]
日期:2012-11-21
卷期号:12 (12): 6192-6197
被引量:135
摘要
Direct observation of delithiated structures of LiCoO2 at atomic scale has been achieved using spherical aberration-corrected scanning transmission electron microscopy (STEM) with high-angle annular-dark-field (HAADF) and annular-bright-field (ABF) techniques. The ordered Li, Co, and O columns for LiCoO2 nanoparticles are clearly identified in ABF micrographs. Upon the Li ions extraction from LiCoO2, the Co-contained (003) planes distort from the bulk to the surface region and the c-axis is expanded significantly. Ordering of lithium ions and lithium vacancies has been observed directly and explained by first-principles simulation. On the basis of HAADF micrographs, it is found that the phase irreversibly changes from O3-type in pristine LiCoO2 to O1-type LixCoO2 (x ≈ 0.50) after the first electrochemical Li extraction and back to O2-type LixCoO2 (x ≈ 0.93) rather than to O3-stacking after the first electrochemical lithiation. This is the first report of finding O2-LixCoO2 in the phase diagram of O3-LiCoO2, through which the two previously separated LiCoO2 phases, i.e. O2 and O3 systems, are connected. These new investigations shed new insight into the lithium storage mechanism in this important cathode material for Li-ion batteries.
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