Synthesis and characterization of doped Li[Mn0.5−x/2Ni0.5−x/2Cox]O2 positive electrode materials

Layered positive electrode materials for rechargeable lithium-ion batteries of the general formula Li[Mn0.5−x/2Ni0.5−x/2Cox]1−yMyO2 (x ≤ 1/3, 0 ≤ y ≤ 0.05) were synthesized by a solid state route. The effect of doping elements M on the electrochemical performance was investigated. It was found that doping with niobium or tantalum has a positive effect on the cycling stability compared to the undoped parent compounds (y = 0). High discharge capacities, excellent cycling stabilities and high rate capabilities were achieved.