Sb2O3-modified Li1.1CoO2 material is successfully obtained by solid state reaction. The modified phase maintains the merit of high packing density of bare Li1.1CoO2; on the other hand, it is proved that the addition of Sb2O3 during the preparation effectively removes the excess Li and associated structure defect in the material. XRD, EDAX and ICP-AES measurements all reveal that the coating layer is a solid solution of LiCo1−x Sb x O2. Cycling and thermal test indicates that, comparing to the bare Li1.05CoO2, Sb2O3-modified Li1.1CoO2 material shows improved cycleabilty as well as higher thermal stability.