Surface modification of Mg-doped spinel with different Li-containing manganese oxides

Mg-doped spinel LiMg_0.05Mn_1.95O₄ was synthesized and coated with three types of Li-containing manganese oxides (Li₂Mn₄O₉, Li₄Mn₅O₁₂, and LiNi_0.5Mn_1.5O₄) to improve the cycling properties at room temperature and at 50 °C via a coprecipitation method. The as-prepared spinels were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma (ICP), and electrochemical tests. The results indicate that all the coated samples show enhanced electrochemical performance including higher initial charge-discharge capacities and more stable cycling properties as well as improved coulombic efficiency. Especially, the LiNi_0.5Mn_1.5O₄-coated sample delivers the highest initial discharge capacity of 129 mAh/g with capacity retention of 82.5 % as well as the best coulombic efficiency of 92.1 %. This improved performance could be attributed to the enhanced electrochemical kinetics by successful surface modification of spinels with Li-containing manganese oxides via coprecipitation method.