CeVO4-coated LiNi0.6Co0.2Mn0.2O2 as positive material: towards the excellent electrochemical performance at normal and high temperature

The CeVO4-coated LiNi0.6Co0.2Mn0.2O2 (NCM 622) cathode materials are successfully synthesized by hydrothermal method. The structure, morphology and electrochemical properties of the surface modified NCM 622 materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and constant current charge and discharge test. The SEM images and XPS patterns show that nanosized CeVO4 layer is uniformly coated on the surface of NCM 622 active material. Furthermore, the electrochemical performance of all the CeVO4-coated NCM 622 samples are improved significantly. 3 wt% of CeVO4-coated NCM 622 cathode material exhibits specific capacity of 146.1 mAh g-1 and excellent capacity retention (89.63%) between 2.8 and 4.3 V after 100 cycles at elevated temperature (60 A degrees C). The alternating current impedance and cyclic voltammetry tests show that the CeVO4 coating can reduce the electrode polarization and enhance the electrochemical activity of cathode materials.