Effects of transition metal doping and surface treatment to improve the electrochemical performance of Li₂MnO₃

A novel strategy to improve the electrochemical performance of Li ₂MnO₃ using transition metal doping by the mechanochemical process is proposed. Li₂MnO₃ precursors are treated with transition metal containing chemicals in the mechanochemical process, followed by heat treatment. Cr containing Li₂MnO₃, with only 1 mol% Cr doping, exhibits unique electrochemical properties with a large initial discharge capacity of 234.9 mAh g^-1, which is superior to the 205.0 mAh g^-1 of pristine Li₂MnO₃, and all other transition-metal containing oxides. The structures of Li₂MnO ₃ and Li₂MnO₃ with the transition metal element doping (TM-Li₂MnO₃) are studied by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and the electrochemical characteristics are further investigated using electrochemical impedance spectroscopy (EIS) measurements.