Niobium doping of Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials with enhanced structural stability and electrochemical performance

Lithium-rich layered oxides with high energy density have been intensively investigated as advanced lithium-ion batteries cathode materials. However, capacity degradation and voltage decay caused by irreversible lattice oxygen loss and structural transformation during cycling restrict their application. Herein, we proposed a high valance cations Nb5+ doping strategy and synthesized a series of Li1.2Mn0.54-x/3Ni0.13-x/3Co0.13-x/3NbxO2 (x = 0, 0.01, 0.02 and 0.03) cathode materials. The effects of Nb5+ doping on crystallographic structure and electrochemical property were systematically studied. In virtue of the large ionic radii and strengthened Nb–O bonds, the doped samples present commendable structural stability and expanded interlayer spacing for Li-ions migration, which ensures the upgraded cyclic stability and rate performance. In particular, the electrode with x = 0.02 delivers a discharge specific capacity of 265.8 mAh g-1 at 0.2 C with decelerated voltage decay, while 86.9% capacity are remained after long-term cycles. Moreover, excellent discharge specific capacity of 153.4 mAh g−1 is still attained at 5 C accompanied with enhanced Li-ion diffusion kinetics.