Improvement of the electrochemical performance of Li1.2Ni0.13Co0.13Mn0.54O2 cathode material by Al2O3 surface coating

The layered Li-rich Li1.2Ni0.13Co0.13MN0.54O2 cathode materials have been synthesized by a facile approach and subsequently modified with different amount of Al2O3 nano layer. The microstructure and electrochemical performance of the pristine and Al2O3 coated samples were investigated systematically. It is found that the pristine particles are uniformly coated with Al2O3 layer. In particular, the 3 wt% Al2O3-coated cathode delivers the highest initial discharge capacity of 317.9 mAhg(-1) at 25 mAg(-1) in the voltage window 2.0-4.8 V, and best rate performance (317.9 mAhg(-1) at 0.1 C, 105.6 mAhg(-1) at 10 C), and best cyclability (discharge capacity of 164 mAhg(-1) at 2 C after 200 cycles with capacity retention of 86.3%), which is much better than that of the pristine cathode (discharge capacity of 124 mAhg(-1) at 2 C after 200 cycles with capacity retention of 73.3%). Electrochemical impedance spectroscopy (EIS) shows that the Al2O3 coating can reduce the charge transfer resistance during the cycle, which is attributed to the suppression of the side reactions and the stability of the surface structure of the active materials by Al2O3 oxide coating. These findings provide a research direction for solving serious defects such as large initial irreversible capacity loss and poor cycle stability of lithium-rich cathode materials for lithium ion batteries. (C) 2020 Elsevier B.V. All rights reserved.