Enhanced electrochemical performance of Lithium Metasilicate-coated LiNi_0.6Co_0.2Mn_0.2O₂ Ni-rich cathode for Li-ion batteries at high cutoff voltage

Li₂SiO₃-coated LiNi_0.6Co_0.2Mn_0.2O₂ cathode material has been synthesized and exhibit much better electrochemical performance than pristine LiNi_0.6Co_0.2Mn_0.2O₂ at cut-off voltage 4.6 V. The as-prepared samples are characterized by X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscope, and X-ray photoelectron spectroscopic. The results show that the coating-layer Li₂SiO₃ is not incorporated into the LiNi_0.6Co_0.2Mn_0.2O₂ host structure and coated well on the surface of the active material. The sample coated with 3 mol. % Li₂SiO₃ delivers a capacity of 168 mAh g⁻¹ at 0.2 C after 100 cycles, and remains 85.5% of the first discharge capacity. The capacity retention at 1C is 73.6% after 100 cycles and the first discharge capacity reaches 158 mAh g⁻¹ at 10 C. This superior performance is attributed to the coating layer which restrains the side reactions at electrode/electrolyte interface and enhances structure stability, meanwhile, it can decrease the electrode polarization because it is an excellent Li⁺-ion conductor.