Synthesis and electrochemical characterization of nano-CeO2-coated nanostructure LiMn2O4 cathode materials for rechargeable lithium batteries

LiMn₂O₄ spinel cathode materials were coated with 0.5, 1.0, and 1.5 wt.% CeO₂ by a polymeric process, followed by calcination at 850 °C for 6 h in air. The surface-coated LiMn₂O₄ cathode materials were physically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron microscopy (XPS). XRD patterns of CeO₂-coated LiMn₂O₄ revealed that the coating did not affect the crystal structure or the Fd3m space group of the cathode materials compared to uncoated LiMn₂O₄. The surface morphology and particle agglomeration were investigated using SEM, TEM image showed a compact coating layer on the surface of the core materials that had average thickness of about 20 nm. The XPS data illustrated that the CeO₂ completely coated the surface of the LiMn₂O₄ core cathode materials. The galvanostatic charge and discharge of the uncoated and CeO₂-coated LiMn₂O₄ cathode materials were measured in the potential range of 3.0-4.5 V (0.5 C rate) at 30 °C and 60 °C. Among them, the 1.0 wt.% of CeO₂-coated spinel LiMn₂O₄ cathode satisfies the structural stability, high reversible capacity and excellent electrochemical performances of rechargeable lithium batteries.