Effect of Sb2O3 Modification on Electrochemical Performance of LiMn2O4 Cathode Material

Sb2O3-coated LiMn2O4 is prepared by chemical precipitation method to improve the cycling stability of LiMn2O4. The uncoated and Sb2O3-coated LiMn2O4 materials are characterized by the X-ray diffraction (XRD), Transmission electron microscope (TEM) and X-ray photoelectron energy spectrum (XPS). The results indicate that the crystal structure of LiMn2O4 is not affected by the Sb2O3 coating but lattice constant has changed, and most Sb2O3 coat on LiMn2O4 surface. Electrochemical test shows that Sb2O3-coating could improve the cycling performance of LiMn2O4. At room temperature, the capacity retention of 2.0 wt. % Sb2O3-coated material is 93.5% after 60 cycles while that of the bare sample is only 86.3%. Electrochemical impedance spectroscopy (EIS) demonstrates that the improved performance of the Sb2O3-coated LiMn2O4 is due to suppress the augment of charge transfer resistance during cycling, which indicates that the coating decreases the surface reaction between cathode and electrolyte. Data from TG-DSC studies show that the thermal stability of the surface modified LiMn2O4 electrode is improved.