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

Abstract

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.