锂离子电池正极材料LiNi_(1/3-x)Nb_xCo_(1/3)Mn_(1/3)O_2的制备与表征

Preparation and characterization of LiNi_(1/3-x)Nb_xCo_(1/3)Mn_(1/3)O_2 cathode materials for Li-ion batteries

通过高温固相法制备了LiNi1/3-xNbxCo1/3Mn1/3O2正极材料。采用X射线衍射、扫描电镜分析以及电化学分析等手段对其微观结构、表面形貌和电化学性能进行了研究。结果表明,当x=0.005时,高温固相法能得到结晶良好的LiNi1/3-xNbxCo1/3Mn1/3O2,颗粒分布均匀,有团聚现象发生,二次团聚粒径约为10μm左右。Nb5＋的引入降低了材料的阳离子混排程度,完善了材料的层状结构,提高了材料的电化学性能。在2.8-4.2V、0.2C下的首次充放电比容量分别为211.3和152.4mA·h/g。50次循环后的充放电比容量分别为127.4和124.6mA·h/g,容量保持率为97.8%,具有较好的循环性能。

The layered LiNi1/3-xNbxCo1/3Mn1/3O2 cathode material for Li-ion batteries was synthesized by high-temperature solid-state method.The microstructure,surface morphology and electrochemical properties were characterized by X ray diffraction（XRD）,scanning electron microscopy（SEM）and electrochemical analysis.LiNi1/3-xNbxCo1/3Mn1/3O2 with good crystallization and uniform particle size could be obtained by high-temperature solid-state method.It showed a reunion phenomenon and the average secondary particle size was about 10μm in diameter.However,the decreased cation mixing,ordered hexagonal structure and better electrochemical performance were observed when added Nb material.The initial charge/discharge capacities of LiNi1/3-xNbxCo1/3Mn1/3O2′powder were 211.3and152.4mA·h/g respectively in the voltage range of 2.8-4.2V,and at 0.2Crate.The capacities were127.4and 124.6mA·h/g respectively after 50 cycles and capacity retained 97.8%.