Abstract: The development of nickel-rich and low-cobalt cathode materials is currently an effective way to improve the energy density and reduce the cost of lithium-ion batteries. However, as Ni content increases, Ni-rich layered oxides have some problems, such as difficult precursor synthesis, structural instability, and high interfacial activity, which hinder the promotion of Ni-rich layered oxide cathode materials. In this paper, a structurally stable LiNi_0.8Mn_0.1Co_0.1O₂ (NCM811) cathode material was prepared by an optimized co-precipitation method, while a fast ionic conductor Li_1.5Y_0.5Zr_1.5(PO₄)₃ coating was uniformly wrapped on the surface of NCM811 material to overcome the difficulties of interfacial structural instability and electrolyte corrosion. At a high cut-off voltage of 4.5 V, the discharge specific capacity of the modified sample is 214.2 mAh·g^-1 at 0.2 C and up to 158.8 mAh·g^-1 at 10 C, which is much higher than the 203.7 mAh·g^-1 (0.2 C) and 82.7 mAh·g^-1 (10 C) of the original sample. Meanwhile, the capacity retention rate of the modified sample after 200 cycles of 1 C at 4.3 V is as high as 84.7%, which is higher than that of the original sample (61.94%).

Key words: lithium-ion battery, co-precipitation method, fast ionic conductor, surface modification, high rate performance, high cut-off voltage