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

Abstract LiMn 2 O 4 spinel cathode materials were coated with 1.0, 2.0 and 3.0 wt.% of La 2 O 3 by polymeric process, followed by calcinations at 850 °C for 6 h in air. The surface coated LiMn 2 O 4 cathode materials were physically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and XPS. XRD patterns of La 2 O 3 -coated LiMn 2 O 4 revealed that the coating did not affect the crystal structure and space group Fd 3 m of the cathode materials, compared to the uncoated LiMn 2 O 4 . 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 La 2 O 3 was completely coated over the surface of the LiMn 2 O 4 core cathode materials. The galvanostatic charge and discharge of the uncoated and La 2 O 3 -coated LiMn 2 O 4 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 La 2 O 3 -coated spinel LiMn 2 O 4 cathode has improved the structural stability, high reversible capacity and excellent electrochemical performances of the rechargeable lithium batteries.