1D Nb-doped LiNi1/3Co1/3Mn1/3O2 nanostructures as excellent cathodes for Li-ion battery

Abstract The effect of niobium (Nb) doping in one-dimensional (1D) nanostructured LiNi1/3Co1/3Mn1/3O2 (NCM) cathode has been investigated for this study. Nb-doped NCM nanofibres have been prepared through an electrospinning method followed by controllable sintering process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed that Nb-doping can effectively reduce cation mixing, thus improve the structural stability. In addition, due to the valence compensation balance, Mn4+ ions are partially reduced to Mn3+ ions, which can further improve the conductivity and stable cycling performance. Therefore, increased discharge capacities, high first cycle efficiencies and superior cycling and rate behaviors are observed between normal voltage limits for the Nb-doped NCM compositions in electrochemical cells. Specifically, Nb-doped NCM nanofibres achieve a high discharge capacity of 200.4 mAh/g at 0.1 C with a high Coulombic efficiency of 92.3%. Moreover, a high discharge capacity of 118.7 mAh/g even at 5 C with 83.3% capacity retention after 200 cycles is also achieved. Also, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results demonstrate that Nb-doping can mitigate the electrochemical polarization of NCM and improve the lithium ion diffusion coefficient, leading to the improvement of electrochemical performances. It is highly expected that our findings can provide a general approach to improve the electrochemical properties of cathode materials for lithium-ion batteries.