Enhanced high voltage electrochemical performance of LiNi1/3Co1/3Mn1/3O2 cathode material by coating with Li3VO4

Li3VO4 is successfully coated on the surface of LiNi1/3Co1/3Mn1/3O2 cathode material via a simple wet-chemical method. The structure and morphology of Li3VO4-coated LiNi1/3Co1/3Mn1/3O2 are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Transmission electron microscope (TEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). It was found that the LiNi1/3Co1/3Mn1/3O2 powder is homogeneously wrapped by Li3VO4 layer. Electrochemical tests demonstrate that the Li3VO4-coated sample exhibits excellent cycling performance with 90.8% capacity retention at 1C after 100 cycles under a high cutoff voltage of 4.6 V, which is higher than 79.4% for the bare one. Meanwhile, the rate capability of the coated sample is also improved even under the high current densities. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses reveal that Li3VO4 coating could suppress the side reaction between the electrode and electrolyte during the repeated cycles. Moreover, XRD and SEM characterizations of cycled electrodes show that Li3VO4 coating layer plays an important role in alleviating structural damage of LiNi1/3Co1/3Mn1/3O2 and protecting LiNi1/3Co1/3Mn1/3O2 from electrolyte.