Synthesis and characterization of spinel type high-power cathode materials Li M xMn 2−x O 4 (M=Ni, Co, Cr)

Abstract

The transition metal-doped spinel cathode materials, LiM 0.5Mn 1.5O 4 (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 μm. Oxidation states of Ni, Co and Cr were found to be 2+, 2+ and 3+ as revealed by X-ray photoelectron spectroscopy. During discharging, LiNi 0.5Mn 1.5O 4 and LiCo 0.5Mn 1.5O 4 sample shows more than 130 mAh/g between 3.5 and 5.2 V at a current density of 0.65 mA/cm 2 and well developed plateau around 5 V, respectively.