Preparation and Electrochemical Performance of Na+-stabilized Layered LiNi0.6Co0.2Mn0.2O2 Cathode Material for Lithium-ion Batteries

摘要

Na-doped Li0.98Na0.02Ni0.6Co0.2Mn0.2O2 cathode material was synthesized through a simple oxalate co-precipitation.Powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), inductively coupled plasma-atomic emission spectrometry(ICP-AES), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge tests were employed to analyze the particle morphology, crystal structure and electrochemical properties of the as-prepared materials.Results indicate that the Na-stabilized sample has a more ordered α-NaFeO2 structure(space group R3m), reduced Li+/Ni2+ cation mixing and enlarged Li layer spacing, which facilitates the fast insertion and extraction of Li+ ions in the bulk structure.Electrochemical results confirm that the Na-stabilized sample has excellent cycling stability and high rate performance.After 100 cycles at 1C between 2.7 V and 4.3 V, the cathode delivers a discharge capacity of 146 mA·h/g with capacity retention of 95.4%.At 0.1C, 0.2C, 0.5C, 1C, 3C, 5C, 10C and 20C, the specific capacities of the material are 181, 168, 162, 155, 143, 136, 126 and 113 mA·h/g, respectively.The Na-doping method is facile and feasible, which can provide some valuable reference for synthesizing other high rate and high capacity layered anode/cathode oxides.

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