Synthesis and Electrochemical Properties of Y-Doped LiNi1/3Mn1/3Co1/3O2 Cathode Materials for Li-Ion Battery

The layered Li(Ni1/3Co1/3Mn1/3)1-xYxO2 cathode materials (x = 0, 0.03, 0.06, 0.09) were prepared by a co-precipitation method. The properties of the Y-doped LiNi1/3Mn1/3Co1/3O2 were investigated by X-ray diffraction (XRD), scanning electron microscopic (SEM), and electrochemical measurements. XRD studies show that the Y-doped LiNi1/3Mn1/3Co1/3O2 has the same layered structure as the undoped LiNi1/3Mn1/3Co1/3O2. SEM images exhibit that the particle size of Y-doped LiNi1/3Mn1/3Co1/3O2 is smaller than that of the undoped LiNi1/3Mn1/3Co1/3O2 and the smallest particle size is only about 2μm. The Y-doped LiNi1/3Mn1/3Co1/3O2 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra (EIS). The optimal doping content of Y is that x = 0.06 in the Li(Ni1/3Co1/3Mn1/3)1-xYxO2 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through Y-doping. The improved electrochemical performances of the Y-doped LiNi1/3Mn1/3Co1/3O2 cathode materials are attributed to the addition of Y3+ ion by stabilizing the layer structure.