LiNiO2 and LiNi0.5Co0.5O2 cathodes for lithium-ion batteries were synthesized with co-precipitation method and their electrochemical property was characterized by Galvanostatic cycling. Meanwhile, plane-wave pseudopotential method base on density functional theory was used to calculate average cell voltage and the electronic structure of LiNiO2 and LiNi0.5Co0.5O2. The experimental and computational results showed that the average voltage of the cell decreased as Li-ion intercalated to the host cathode (discharge); The potential of LixNi0.5Co0.5O2 was higher than that of LixNiO2 (when 0.25≤x≤0.5). The calculations also indicated that the distortion of the NiO6 octahedron in LixNiO2 was decreased by Co-doped. During the Li-ion intercalates to the host cathode, the micro-structures of NiO6 and CoO6 in the LixNi0.5Co0.5O2 were mutually stabilized, the Jahn-Teller effect was weakened and the electrochemical properties of the materials were enhanced.