Preparation and properties of LiNi_0.5Co_0.2Mn_0.3O₂@WO₃ composite cathode materials

In order to improve the electrochemical performance of LiNi_0.5Co_0.2Mn_0.3O₂ (NCM), WO₃ coated NCM (NCM@WO₃) composite cathode materials were synthesized with a liquid phase evaporation process. The structure and morphology of the NCM@WO₃ composite were characterized by XRD, SEM and TEM. The electrochemical performance of the NCM@WO₃ composite was characterized by charge-discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the NCM@WO₃ composite with 3wt% WO₃ has the best performance, it delivers an initial discharge capacity of 179.9 mA·hg^-1 with a low irreversible capacity loss of 42.4 mA·hg^-1 at 0.5 C, and the capacity retention after 50 cycles is 98.3%. The improved electrochemical properties of the NCM@WO₃ composite are mainly attributed to the WO₃ coating, which improves the lithium ions diffusion rate and suppresses the interface reaction between the cathode and the electrolyte.