Abstract: Gallium-doped layered LiCo_0.3-xGa_xNi_0.7O2 materials were synthesized by a sol-gel method. Single phase of LiCo_0.3-xGa_xNi_0.7O2 could be prepared in 0≤x≤0.5 region. The samples were characterized by means of XRD, particle size, BET and charge/discharge test. The discharge capacity of {LiCo_0.3-xGa_xNi_0.7O2} increased with the increase of gallium contents. The initial discharge capacity of {LiCo_0.25Ga_0.05Ni_0.7O2} was 177.5 mA·h/g between 2.8 and 4.3 V at 0.2 C and had no capacity loss after 25 cycles. Furthermore, the discharge capacity of LiCo_0.25Ga_0.05Ni_0.7O2 was completely recovered after cycling at high discharge-rates. The discharge capacity increased with the upper cut-off voltage limit with a good cycle-ability regardless of the upper cut-off voltage limit. Meanwhile, only one phase reaction took place during the electrochemical oxidation and reduction process, indicating no structure degradation.

Key words: Lithium ion batteries, Cathode materials, LiCo_0.3-xGa xNi_0.7O₂, Gallium-doping