Synthesis and electrochemical properties of LiMn2O4 and LiCoO2-coated LiMn2O4 cathode materials

The synthesis of spinel LiMn2O4 material by a spherical MnO2 precursor route is reported in this paper. Hydrothermal and solid-state reactions were adopted to investigate the effects of synthetic methods on the morphologies and electrochemical characteristics of the LiMn2O4 products, respectively. LiCoO2-coated LiMn2O4 microspheres were also prepared by a sol-gel route based on the as-prepared LiMn2O4 microspheres. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDX), and inductively-coupled plasma emission spectrograph (ICP-ES). The results show that LiMn2O4 octahedrons can be obtained under hydrothermal conditions while LiMn2O4 microspheres can be prepared by the solid-state reaction. Electrochemical characterization reveals that the resulting LiMn2O4 microspheres and LiCoO2-coated LiMn2O4 microspheres display much better cycling properties than those of LiMn2O4 octahedrons. (C) 2011 Elsevier B.V. All rights reserved.