Layered Li_1+x(Ni_0.33Co_0.33Mn_0.33)O₂ cathode material prepared by microwave assisted solvothermal method for lithium ion batteries

Highlights: • Microwave assisted solvothermal method. • Effect of (0.05–0.2) mol% of excess lithium in layered Li_1+x(Ni_0.33Co_0.33Mn_0.33)O₂. • Different calcination temperature. • Voltage-cut off optimization. • Conductivity and electrochemical performance correlation. - Abstract: Layered hexagonal structure Li_1+x(Ni_0.33Co_0.33Mn_0.33)O₂ (LNCM) (x = 0, 0.05, 0.1, 0.15 and 0.2 mol%) compounds were prepared by microwave assisted solvothermal method at two different calcination temperature of 850 and 950 °C. The phase purity of the LNCM compounds was confirmed by Rietveld refined XRD pattern, Raman, and HRTEM studies. The average particle sizes were in the submicron range as confirmed by SEM and TEM analysis. Galvanostatic cycling studies were made in various voltage range, 2.5 to 4.4/4.6/4.8 V at a current rate of 0.2 C. Among all the compounds, LNCM prepared at 950 °C (HS3) exhibited an initial discharge capacity of 197 mAh/g and maintained a capacity of 180 mAh/g at the end of 40^th cycle in 2.5–4.6 V window, indicating an excellent capacity retention. HS3 shows the electrical conductivity of 9.31 × 10⁻⁶ S/cm, which was higher than all the other compounds and discussed the reason for the improved electrochemical performance.