In order to overcome the capacity fading of LiCoO2 cathode material cycled in the voltage of 3.0–4.5V (vs. Li/Li+), electrochemically active Li[Li0.2Mn0.6Ni0.2]O2 was coated onto the surface of LiCoO2 by sol-gel method. The detrimental surface effects arising from the high Co-content are countered by the Li[Li0.2Mn0.6Ni0.2]O2 coating. The surface morphology and structure of bare and coated LiCoO2 is characterized by scanning electron microscope (SEM) and X-ray diffraction spectroscopy (XRD). It is found that LiCoO2 exhibits better high-voltage performance after coating with Li[Li0.2Mn0.6Ni0.2]O2 than before. Besides, the coating layer can significantly suppress the dissolution of Co in the electrolyte. Comparative data for the coated and uncoated materials are presented and discussed.