Enhancement of the electrochemical performances for LiNi0.6Co0.2Mn0.2O2 at high cut-off voltage by an effective dual-coating

Layered LiNi0.6Co0.2Mn0.2O2 as a promising cathode material for lithium-ion batteries possesses high theoretical capacity and broad application prospects. However, the destruction of structure during the cycles and the insufficient conductivity severely restrict the cycle life and rate capacity, especially at high cut-off voltage. As an improvement, the dual-coating of LiAlO2 and graphene oxide (GO) was designed to modify the microstructure and migration dynamics of NCM622 surface. Compared to single coating, LiAlO2/GO showed a synergistic effect that simultaneously increased ion/electron transfer rate, reversibility and cycling stability of the cathode material. As a result, the initial capacity of the dual-coating material was 182.6 mAh/g at 200 mA/g (1 C) with a capacity attenuation of 0.06% per cycle in 200 cycles, while it was 222.6 mAh/g at 20 mA/g (0.1 C), and the rate capacity was 100.4 mAh/g at 2000 mA/g (10 C) in a voltage range of 3.0–4.5 V.