MgO-coated Li1.17Mn0.48Ni0.23CO0.12O2 was synthesized via co-precipitation method followed by a solid state reaction at 500 degrees C. The particle morphology and crystal structure features were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The electrochemical properties of samples were monitored by galvanostatic charge and discharge cycling test, electrochemical impedance spectra (EIS) test and cyclic voltammetry (CV) test. In contrast, 2 wt.% MgO-coated cathode material shows better cyclic performance than others. The Li1.17Mn0.48Ni0.23CO0.12O2/2%MgO oxide delivers an initial discharge capacity of 260.3 mAh g(-1) between 2.0 V and 4.8 Vat 0.1 C-rate (1 C-rate = 358 mA g(-1)), and has a capacity retention of 99.5% after 10 cycles at 0.1 C-rate. (C) 2013 Elsevier B.V. All rights reserved.