Comparative study of Al2O3, SiO2 and TiO2-coated LiNi0.6Co0.2Mn0.2O2 electrode prepared by hydrolysis coating technology

Sa？etak In this work, Al, Si and Ti oxides are used to modify the surface of LiNi0.6Co0.2Mn0.2O2 (NCM622) electrode through the hydrolysis coating technology. SEM and TEM results revealed that three prepared oxide layers have different uniformity and morphology. Also, charge-discharge results showed different initial discharge capacity and cycle ability of three different oxide coatings. It is shown that when the temperature is increased from 25 to 50 °C, the capacity retention of Al2O3-coated NCM622 is reduced by only 4 %, what demonstrated the best ability of this oxide to restrain cycle deterioration. Additionally, when the charge cutoff voltage is increased to 4.6 V, Al2O3-coated NCM622 showed 74 % of capacity retention. As the number of charge-discharge cycles increases, the dissolution of some transition metal ions may be restrained by Al2O3 layer. Generally, the enhanced electrochemical performance of Al2O3-coated NCM622 could be ascribed to the suppression of mutual reaction between electrode and electrolyte and improvement of structural stability of the material by Al2O3 coating