Synthesis and electrochemical characterizations of nano-La2O3-coated nanostructure LiMn2O4 cathode materials for rechargeable lithium batteries

LiMn2O4 spinel cathode materials were coated with 1.0, 2.0 and 3.0 wt.% of La2O3 by polymeric process, followed by calcinations at 850 °C for 6 h in air. The surface coated LiMn2O4 cathode materials were physically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and XPS. XRD patterns of La2O3-coated LiMn2O4 revealed that the coating did not affect the crystal structure and space group Fd3m of the cathode materials, compared to the uncoated LiMn2O4. The surface morphology and particle agglomeration were investigated using scanning electron microscopy and the TEM image showed a compact coating layer on the surface of the core materials that had average thickness of about 100 nm. XPS data illustrated that the La2O3 was completely coated over the surface of the LiMn2O4 core cathode materials. The galvanostatic charge and discharge of the uncoated and La2O3-coated LiMn2O4 cathode materials were carried out in the potential range of 3.0 and 4.5 V at 30 °C and 60 °C. Among them, 2.0 wt.% of La2O3-coated spinel LiMn2O4 cathode has improved the structural stability, high reversible capacity and excellent electrochemical performances of the rechargeable lithium batteries.