Advanced electrochemical performance of Li[Ni(1/3-x)FexCo1/3Mn1/3]O-2 as cathode materials for lithium-ion battery

Li[Ni(1/3-x)FexCo1/3Mn1/3]O-2 (x = 0, 0.05) cathode materials with alpha-NaFeO2 structure were synthesized by co-precipitation method. Hexagonal a and c lattice parameters increased with Fe-dopant. The heat treatment process of precursor were investigated by TG-DTA, the structures of samples were confirmed by X-ray diffraction (XRD) and Fourier Transform Infrared spectra (FT-IR), the distribution of narrow particle size and morphologies were observed by scanning electron microscopy (SEM) and the charge and discharge capacity and electrochemical cycle stability were tested by Battery Testing System (BTS). In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the reaction of lithium ion insertion and extraction from materials. The results indicated that the structure of dopant samples was more stable than that of the native and the discharge capacity and the electrochemical cycle stability were also improved by doping Fe. (C) 2008 Elsevier Ltd. All rights reserved.