Enhancing the high-voltage performances of Ni-rich cathode materials by homogeneous La2O3 coating via a freeze-drying assisted method

• Published in: Ceramics international Vol. 44; no. 12; pp. 14660 - 14666
• Main Authors: Ren, Ting, Zhang, Jufeng, Wang, Ding, Dong, Peng, Duan, Jianguo, Li, Xue, Rao, Shuai, Huang, Dianhua, Zhang, Yingjie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.08.2018
• Subjects: Electrochemical performance; Freeze-drying; High voltage; Layered cathode materials; LiNi0.5Co0.2Mn0.3O2; Electrochemical performance; High voltage; Freeze-drying; Layered cathode materials; LiNi0.5Co0.2Mn0.3O2
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2018.05.092

The major limitations of layered LiNi0.5Co0.2Mn0.3O2 cathode materials are their severe capacity decay and marked impedance increase under a high cutoff voltage. Herein, a LiNi0.5Co0.2Mn0.3O2 powder was successfully encapsulated by a compact and continuous La2O3 thin layer via a facile freeze-drying method. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The excellent thermal stability and favorable lithium ion conductivity of the La2O3-modified sample lead to a substantial improvement in its electrochemical performances. In particular, the coated sample exhibits a capacity retention of 80% at 1 C over 150 cycles, while that of the bare electrode is only 58% at a high cutoff voltage of 4.6 V. The alternating current impedance and cyclic voltammetry tests reveal that the La2O3 coating can reduce the cell polarization and enhance the electrochemical activity of cathode materials.