Improvement of LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials by Nano-MgO doping

Nano-sized M₃O₄ (M=Ni_1/3Co_1/3Mn_1/3) powder with a spinel structure was prepared by sintering co-precipitated M(OH)₂ at 500 °C for 5 h. The so-obtained M₃O₄ was then mixed with LiOH and different amounts of nano-MgO. The mixture was sintered at 850 °C for 24 h to synthesize Li(Ni_1/3Co_1/3Mn_1/3)_1-xMg_xO₂ (x=0, 0.01, 0.02, 0.03, 0.04,0.05) cathode materials. The lattice parameters increased while the diffusion coefficients of Li ⁺ ion showed an increasing and then decreasing trend with an increase in the amount of Mg infstitution. Li(Ni_1/3Co_1/3Mn_1/3)_0.98Mg_0.02O₂ had the highest Li⁺ ion diffusion coefficients, which were 29.20× 10^-11 cm²·s^-1 for Li⁺ de-intercalation and 4.760×10^-11 cm²·^-1 for Li⁺ intercalation. Its discharge capacity at 3C rate was 139.3 mAh·g^-1, which is 9.5 mAh·g^-1 higher than that of the pristine material. Furthermore, its cycle performance was also improved significantly compared with the un-doped counterpart.