以水和乙二醇的混合溶液作为溶剂,草酸作为络合剂和沉淀剂,采用溶剂热法制备出粒径为300～500nm的块状LiNi0.6Co0.2Mn0.2O2(NCM622)材料。通过湿法包覆,在NCM622颗粒表面形成一层带有许多介孔的Co3O4包覆层。通过X射线衍射仪、透射电子显微镜、恒电流充放电技术、循环伏安法以及交流阻抗谱等手段对材料的结构、形貌和电化学性能(放电性能、循环性能、倍率性能和材料内阻)进行表征。结果表明:经过Co3O4包覆后的电极材料在电化学性能方面都有一定改善。尤其是3% Co3O4包覆的材料,电化学性能最为优异。在0.1C倍率条件下首次放电比容量达到191mAh/g,在0.2C下循环100圈,材料的容量保持率从最初的61.2%提高到87%,且包覆后的阻抗也明显降低。
Using mixed solution of water and ethylene glycol as solvent,oxalic acid as complexing agent and precipitant,granule-like LiNi0.6Co0.2Mn0.2O2(NCM622) nanoparticles with a particle size of 300～500 nm was prepared by solvothermal method.Co3O4 coating with many mesopores was formed on the surface of the NCM622 particles by wet coating.The morphology and electrochemical properties (discharge performance,cycle performance,multiplier performance and material internal resistance) of the material were characterized by X-ray diffractometer,transmission electron microscope,constant-current charge-discharge technology,cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS).The results shown that the electrode material coated by Co3O4 had some improvement in electrochemical performance.In particular,the material coated with 3% Co3O4 had the best electrochemical performance.At the 0.1C rate,the first discharge specific capacity reached 191mAh/g,and the cycle was maintained at 0.2C for 100 cycles.The capacity retention rate of the material increased from 61.2% to 87%,and the impedance after coating also decreased significantly.
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