Suppressing detrimental phase transitions on LiNi0.87Co0.13O2 cathode for Li-ion batteries via carbon coating

Abstract

An amorphous carbon layer is obtained from the carbonization of sucrose and used as a coating material to improve the electrochemical properties of LiNi0.87Co0.13O2 cathode at a high temperature for Li-ion batteries. The carbon layer facilitates a decrease in phase transitions as well as an increase in charge/discharge capacity, cycling stability, and rate capability. The carbon-coated electrode modified using 3 wt% sucrose exhibits an ultra-high initial discharge capacity of 234.6 mAh/g with a large Coulombic efficiency of 98.53 % at 0.1C. The cycling stability of the carbon-modified sample is improved to approximately 80 % after 100 cycles at 55 °C at the current rate of 0.5C. Additionally, the coated sample retains super-high capacities at high rates, which are 218.8 mAh/g (93.27 % initial discharge capacity at 0.1C) at 2C and 188.5 mAh/g (80.35 % initial discharge capacity at 0.1C) at 5C, respectively. However, the bare sample only exhibits a discharge capacity of 204.4 mAh/g at 2C and 179.4 mAh/g at 5C. These excellent results can be attributed to the carbon-coated layer, which suppresses the chemical reactions between the cathode material and electrolyte, extracts the residual lithium hydroxide, and prevent the incursion of the solid electrolyte interface on the surfaces of the oxide particles.