Electrochemical characterizations of surface modified LiMn_2O_4 cathode materials for high temperature lithium battery applications

摘要

LiMn_2O_4 spinel cathode materials were coated with 2.0 wt.% of La_2O_3 by polymeric process followed by calcinations at 400 ℃ and 800 ℃ for 6 h in air. The surface coated LiMn_2O_4 cathode materials were physically characterized using X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy and X-ray photoelectron spectroscopy. La_2O_3-coated LiMn_2O_4 coating did not affect the crystal structure and space group Fd3m of the cathode materials compared to the uncoated LiMn_2O_4. The surface morphology and partide agglomeration were investigated and compact coating layer on the surface of the core materials. La-2O_3 was completely coated over the surface of the LiMn_2O_4 core cathode materials. The galvanostatic charge and discharge of the La_2O_3-coated LiMn_2O_4 cathode materials were carried out at 0.1 mA/g in the range of 3.0 and 4.5 V at 30 ℃ and 60 ℃. Based on the results, La_2O_3.coated spinel LiMn_2O_4 cathode at 800 ℃ has improved the structural stability, high reversible capacity and excellent electrochemical performances of the rechargeable lithium batteries.