Relationships between Structural Changes and Electrochemical Kinetics of Li-Excess Li1.13Ni0.3Mn0.57O2 during the First Charge

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• 作者：Yuhui Wang ; Xiaofei Bie ; Kristian Nikolowski ; Helmut Ehrenberg ; Fei Du ; Manuel Hinterstein ; Chunzhong Wang ; Gang Chen ; Yingjin Wei
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：February 21, 2013
• 年：2013
• 卷：117
• 期：7
• 页码：3279-3286
• 全文大小：500K
• 年卷期：v.117,no.7(February 21, 2013)
• ISSN：1932-7455

文摘

Li-excess cathode material, Li_1.13Ni_0.3Mn_0.57O₂, was synthesized by the sol鈥揼el method. The material has a reversible discharge capacity of 200 mAh g^鈥? at a current density of 40 mA g^鈥?. In situ synchrotron X-ray diffraction, electrochemical impedance spectroscopy (EIS), and the galvanostatic intermittent titration technique (GITT) were applied to study the relationships between structural changes and electrochemical kinetics of Li_1.13Ni_0.3Mn_0.57O₂ during the first charge. When the charging potential was below 4.4 V, the c/a structural parameter of the material gradually increased, resulting in a higher layered character. The lithium diffusion coefficients during this process were about 10^鈥?4 cm² s^鈥?. When the charging potential was increased to 4.8 V, the bulk of the material was still maintained in a layered structure with space group symmetry R3̅m. The lithium diffusion coefficient and the charge transfer kinetics rapidly decreased because of the high kinetic barriers associated with concurrent Li⁺ extraction, oxygen loss, and structural rearrangement. Both the lithium diffusion coefficient and the charge transfer kinetics show further decrease at the end of the first charge, indicating severely sluggish kinetics of the 鈥淟i-poor鈥?Li_1.13鈥?i>xNi_0.3Mn_0.57O₂ phase.