In this study, the LiCoO2/LiNi1/3Mn1/3Co1/3O2 mixed cathode electrodes were prepared and their electrochemical performances were measured in a high cut-off voltage. As the contents of LiNi1/3Mn1/3Co1/3O2 in the mixed cathode increases, the reversible specific capacity and cycleability of the electrode enhanced, but the rate capability deteriorated. On the contrary, the rate capability of the cathode enhanced but the reversible specific capacity and cycleability deteriorated, according to increasing the contents of LiCoO2 in the mixed cathode. The cell of LiCoO2/LiNi1/3Mn1/3Co1/3O2 (50:50, wt.%) mixed cathode delivers a discharge capacity of ca. 168mAh/g at a 0.2C rate. The capacity of the cell decreased with the current rate and a useful capacity of ca. 152mAh/g was obtained at a 2.0C rate. However, the cell shows very stable cycleability: the discharge capacity of the cell after 20th charge/discharge cycling maintains ca. 163mAh/g.