Enhanced electrochemical performance of Li-rich Li[Li_0.2Mn_0.52Ni_0.13Co_0.13V_0.02]O₂ cathode materials for lithium ion batteries by Li_1.13Mn_0.47Ni_0.2Co_0.2O₂ coating

Li-rich layered oxides are the most promising cathode candidate for lithium ion batteries with high specific energy. In this work, Li_1.13Mn_0.47Ni_0.2Co_0.2O₂-coated Li [Li_0.2Mn_0.52Ni_0.13Co_0.13 V_0.02]O₂ cathode materials were synthesized via a sol–gel method, and their electrochemical performance was evaluated. Structural and morphological characterizations of the materials demonstrate that Li[Li_0.2Mn_0.52Ni_0.13Co_0.13V_0.02]O₂ particles are covered by Li_1.13Mn_0.47Ni_0.2Co_0.2O₂ particles. Moreover, the Li_1.13Mn_0.47Ni_0.2Co_0.2O₂ coating has no obvious effect on the crystal structure of Li-rich materials. The specific capacity, cycle performance, and rate capability of Li-rich materials are significantly improved with the coating of Li_1.13Mn_0.47Ni_0.2Co_0.2O₂. Materials coated with 1 wt% to 3 wt% Li_1.13Mn_0.47Ni_0.2Co_0.2O₂ exhibit the highest capacity retention of 93% after 100 cycles at 1 C, which is 10% higher than that of the uncoated one. The specific capacity of 3 wt% Li_1.13Mn_0.47Ni_0.2Co_0.2O₂-coated material is 115.9 mAh g⁻¹ at 5 C, and that of the blank sample is 89.8 mAh g⁻¹ under the same condition. The cyclic voltammetry and electrochemical impedance spectra reveal that the enhanced cycle performance and rate capability of the surface-modified Li-rich materials are due to the presence of the Li_1.13Mn_0.47Ni_0.2Co_0.2O₂ coating layer, which restrains structural transformation with cycling and decreases the charge-transfer resistance of the materials.