Improvement of electrochemical properties of LiNi1/3Mn1/3Co1/3O2 by coating with La0.4Ca0.6CoO3

In this paper, La0.4Ca0.6CoO3-coated LiNi1/3Mn1/3Co1/3O2 is successfully prepared by the sol–gel method associated with microwave pyrolysis method. The structure and electrochemical properties of the La0.4Ca0.6CoO3-coated LiNi1/3Co1/3Mn1/3O2 are investigated by using X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. XRD analyses show that the La0.4Ca0.6CoO3 coating does not change the structure of LiNi1/3Co1/3Mn1/3O2. The electrochemical performance studies demonstrate that 2 wt.% La0.4Ca0.6CoO3-coated LiNi1/3Co1/3Mn1/3O2 powders exhibit the best electrochemical properties, with an initial discharge capacity of 156.9 mAh g–1 and capacity retention of 98.9 % after 50 cycles when cycled at a current density of 0.2 C between 2.75 and 4.3 V. La0.4Ca0.6CoO3 coating can improve the rate performance because of the enhancement of the surface electronic/ionic transportation by the coating layer. EIS results suggest that the coating La0.4Ca0.6CoO3 plays an important role in suppressing the increase of cell impedance with cycling especially for the increase of charge-transfer resistance.