The structure and electrochemical properties of the spinel Li-Mn-O compounds with oxygen deficiency were investigated using X-ray diffraction (XRD), charge-discharge test and electrochemical impedance spectra (EIS). A method to remove oxygen deficiency was suggested in this paper. The XRD results indicate that the spinel Li-Mn-O compounds sintered at 750 ℃ under vacuum atmosphere for different hours mostly kept spinel structure with a few of Mn₃O₄ and Li₂MnO₃ impurities. The results of charge- discharge test and EIS showed that the specific capacities were decreased with increasing the amount of oxygen vacancy, and deterioration of the electrochemical properties could be contributed to the increase of the surface film resistance, charge-transfer resistance and the decrease of the intercalation capacities with the amount of oxygen vacancy. Sintering the samples with oxygen defects by addition of LiOH•H₂O or O₂ flowing can remove the oxygen deficiency inside the spinel Li-Mn-O compounds.

Key words: lithium manganese oxide, oxygen defect, electrochemical property