Enhanced Electrochemical Performance and Structural Stability at High Cut-Off Voltage of Monocrystalline LiNi <sub>0.65</sub>Co <sub>0.07</sub>Mn <sub>0.28</sub>O <sub>2</sub> Cathode Material via Nano-Sized Co(OH) <sub>2</sub> Coating

In this paper, micron-sized monocrystalline LiNi0.65Co0.07Mn0.28O2 cathode material is coated by nano-sized Co(OH)2 to optimize the electrochemical performance and structural stability. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy are applied to characterize the as-prepared samples. The characterizations suggest successful coating and excellent structural stability for LiNi0.65Co0.07Mn0.28O22 with 0.5wt% Co(OH)2 coating. Electrochemical tests reveal improved rate capability and outstanding capacity retention of 95.3% and 84.2% after 100 cycles at cut-off voltage of 4.3V and 4.5V, respectively. The enhanced electrochemical property is attributed to the removal of residual lithium compounds by reacting with cobalt hydroxide, which prevents side reaction between electrode and electrolyte, and mitigates the crack generation and propagation during cycling.