The spherical LiCoO₂ used in lithium-ion-batteries was synthesized by a special emulsion method. The influence of the primary particle’s size and the sintering time on the secondary particle was investigated. The inner structure of the spherical LiCoO₂ was researched by SEM and HRTEM. It was found that, the primary particles were finely fused together and there was no nanometer-scale crack or pore on the crystal boundary of the primary particles. The cathode material sintered at 900 ℃ for 4 h showed excellent electrochemical performance with initial discharge capacity of 143 mAh•g^－1.

Key words: pherical LiCoO₂, emulsion, secondary particle, lithium-ion battery, inner structure, HRTEMs