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

Abstract The major limitations of layered LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials are their severe capacity decay and marked impedance increase under a high cutoff voltage. Herein, a LiNi 0.5 Co 0.2 Mn 0.3 O 2 powder was successfully encapsulated by a compact and continuous La 2 O 3 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 La 2 O 3 -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 La 2 O 3 coating can reduce the cell polarization and enhance the electrochemical activity of cathode materials.