Synthesis and electrochemical behavior of Li[Li0.1Ni0.35−x/2CoxMn0.55−x/2]O2 cathode materials

The effect of Co doping in Li[Li0.1Ni0.35−x/2CoxMn0.55−x/2]O2 materials on the electrochemical properties has been investigated. Layered Li[Li0.1Ni0.35−x/2CoxMn0.55−x/2]O2 (x=0–0.3) materials considered to be a solid solution of LiNi0.5Mn0.5O2, LiCoO2, and Li2MnO3 were synthesized using a sol–gel method. The Co doping of x=0.1 showed improved capacity and rate capability comparing to undoped Li[Li0.1Ni0.35Mn0.55]O2. Area-specific impedance (ASI) and AC impedance measurement show that Co-doped electrode has the lower impedance value during cycling. It is considered that the higher capacity and superior rate capability of Co-doping sample, especially for the Li[Li0.1Ni0.3Co0.1Mn0.5]O2, would be ascribed to the reduced resistance of the electrode during cycling.