Mo doping of layered Li (Ni x Mn y Co1-x -y -z M z )O2 cathode materials for lithium-ion batteries

We systematically investigated the effects of Mo doping on the structure, morphology, and the electrochemical performance of Li (NixMnyCo1-x-y-zMz)O2 (NMC) cathode materials for Li-ion batteries. Layered NMC cathodes were synthesized with the ratio of 111, 622, and 226 via spray pyrolysis yielding submicron-sized aggregates in the shape of hollow spherical particles. We performed X-ray diffraction analyses to determine the present phases and the ordering in structure. X-ray diffraction pattern of Mo-doped 111, 226, and 622 cathodes showed well-defined [006]/[102] and [108]/[110] doublets, indicating the layered structure, and good hexagonal ordering. Galvanostatic charge/discharge and electrical impedance spectroscopy measurements were carried out to reveal the effect of Mo doping on the electrochemical performance of the cathodes. Charge/discharge measurements after 20 cycles indicated that the Mo-doped 111 and 622 NMC cathodes performed a capacity retention of 80% and 81% respectively. Present findings reveal the stabilization effect of Mo in layered NMC structure, especially in the case of Ni-rich NMC cathodes.