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.