Synthesis and characterization of spinel type high-power cathode materials LiMxMn2-xO4 (M = Ni, Co, Cr)

The transition metal-doped spinel cathode materials, LiM0.5Mn1.5O4 (M = Ni. Co, Cr) were prepared by solid-state reaction. The structure and morphology of the samples were investigated by X-ray diffraction, Rietveld refinement and scanning electron microscopy (SEM). The diffraction peaks of all the samples corresponded to a single phase of cubic spinel structure with a space group Fd3m. Field-emission SEM shows octahedron like shapes and the primary particles size was between 500 nm and 2 mu m. Oxidation states of Ni, Co and Cr were found to be 2+, 2+ and 3+ as revealed by X-ray photoelectron spectroscopy. During discharging, LiNi0.5Mn1.5O4 and LiCo0.5Mn1.5O4 sample shows more than 130mAh/g between 3.5 and 5.2V at a current density of 0.65mA/cm(2) and well developed plateau around 5 V, respectively. (c) 2007 Elsevier Ltd. All rights reserved.