In this paper, we research the influence of Ni element doping on the structure and electrochemical properties of LiCoO2. The results show that Ni element doping can reduce initial coulomb efficiency and discharge capacity of materials, and the higher the doping amount, the lower the quantity. A small amount of Ni element doping can improve layer structure of the material, and some Ni elements enter Li plane, support Li plane, and better stabilize layer structure of the material. At the same time, a small amount of Ni element doping can reduce charge transfer impedance of the material during charging-discharging process, so that the material has better cyclic performance. However, when Ni doping is too much, structural stability of the material is reduced, charge transfer impedance is increased, and cyclic performance is deteriorated. (C) 2018 The Electrochemical Society.