Synthesis and characterization of multidoped lithium manganese oxide spinel, Li1.02Co0.1Ni0.1Mn1.8O4, for rechargeable lithium batteries

A multidoped spinel, LiCoxNiyMn2−x−yO4 (x=y=0.1), that is of interest as a cathode material for rechargeable lithium batteries has been synthesized by the sol–gel method and characterized by X-ray diffraction (XRD) and electrochemical methods. Electrochemical experiments show that compared with Ni-doped spinel, Co-doped spinel delivers higher initial capacity, but its rate capability is poor. It is interesting to note that the initial capacity is enhanced, significantly when Co is doped into the Ni-doped spinel LiMn2O4, while the rate capability is retained. In other words, the multidoped spinel, LiCoxNiyMn2−x−yO4 shows the best features of the single-doped spinels, LiCoxMn2−xO4 and LiNiyMn2−yO4. Voltage versus capacity studies indicate that the phase transitions are reduced significantly for the multidoped spinel, LiCoxNiyMn2−x−yO4, during charging and discharging. X-ray diffraction data reveal that the diffraction peak intensity ratio of the typical peaks for the cubic phase (3 1 1) and (4 0 0), does not change after charging for the multidoped spinel, LiCoxNiyMn2−x−yO4. This suggests that cation disordering is completely prevented in this multidoped spinel material.