High-Performance Li(Li0.18Ni0.15Co0.15Mn0.52)O2@Li4M5O12 Heterostructured Cathode Material Coated with a Lithium

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• 作者：Xiaofei Bian ; Qiang Fu ; Hailong Qiu ; Fei Du ; Yu Gao ; Lijie Zhang ; Bo Zou ; Gang Chen ; Yingjin Wei
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：27
• 期：16
• 页码：5745-5754
• 全文大小：630K
• ISSN：1520-5002

文摘

The continuous phase transformation to spinel LiMn₂O₄ seriously hinders the electrochemical properties of Li-excess layered oxides in lithium ion batteries. Herein, we prepared a heterostructured Li-excess layered cathode material consisting of a Li(Li_0.18Ni_0.15Co_0.15Mn_0.52)O₂ active material in conjunction with a surface Li₄M₅O₁₂ spinel and a Li₂O-LiBO₂鈥揕i₃BO₃ glass coating layer. The material showed improved electrochemical kinetic properties with respect to its pristine counterpart because the Li₂O鈥揕iBO₂鈥揕i₃BO₃ glass layer not only improved the ionic conductivity of the material but also depressed the side reactions of the electrode with the electrolyte. In addition, the surface Li₄M₅O₁₂ spinel constantly grew inward the bulk of the material during long-term charge鈥揹ischarge cycling instead of the conventional LiMn₂O₄ transformation for the pristine Li(Li_0.18Ni_0.15Co_0.15Mn_0.52)O₂. As a result, the heterostructured cathode material showed overall improved electrochemical performance. An initial discharge capacity of 258.8 mAh g^鈥? was obtained at the 0.2 C rate with remarkable capacity retention of 92.2% after 100 cycles. Moreover, the material showed excellent rate capacity delivering a high discharge capacity of 130.4 mAh g^鈥?and 100.4 mAh g^鈥? at the 10 and 20 C rates, respectively. Differential scanning calorimetry showed that the exothermic temperature of the fully charged electrode was elevated to 324.2 掳C with little thermal release of 232.5 J g^鈥?, demonstrating good thermal safety of the material.