Effect of lithium content on electrochemical property of Li1+x(Mn0.6Ni0.2Co0.2)1-xO2 (0≤x≤0.3) composite cathode materials for rechargeable lithium-ion batteries

In order to confirm the optimal Li content of Li-rich Mn-based cathode materials (a fixed mole ratio of Mn to Ni to Co is 0.6:0.2:0.2), Li1+x(Mn0.6Ni0.2Co0.2)1-xO2 (x=0, 0.1, 0.2, 0.3) composites were obtained, which had a typical layered structure with and C2/m space group observed from X-ray powder diffraction (XRD). Electron microscopy micrograph (SEM) reveals that the particle sizes in the range of 0.4-1.1 μm increase with an increase of x value. Li1.2(Mn0.6Ni0.2Co0.2)0.8O2 sample delivers a larger initial discharge capacity of 275.7 mA·h/g at the current density of 20 mA/g in the potential range of 2.0-4.8 V, while Li1.1(Mn0.6Ni0.2Co0.2)0.9O2 shows a better cycle performance with a capacity retention of 93.8% at 0.2C after 50 cycles, showing better reaction kinetics of lithium ion insertion and extraction.