富锂层状正极材料Li_(1.18)Ni_(0.15)Co_(0.15)Mn_(0.52)O_2的制备及性质研究

Synthesis and characterizations of Li-excess layered cathode materials for Li-ion battereis

采用溶胶-凝胶法制备了富锂层状材料Li1.18Ni0.15Co0.15Mn0.52O2．通过 X射线衍射仪（XRD）、X-射线光电子能谱（XPS）和扫描电子显微镜（SEM）分别对材料的结构、形貌进行了分析．XRD结果表明，材料属α-NaFeO2型层状结构；XPS结果表明，材料中的Ni，Co和Mn的价态分别为＋2，＋3和＋4价；SEM结果表明，材料颗粒尺寸分布在200～400 nm，且颗粒之间分散比较均匀，无明显的团聚现象；电化学测试结果表明，材料在使用不同电解液进行充放电时，曲线的形状相似，但是充放电容量有所不同．其中在1 mol·L-1LiPF6作为溶质，碳酸亚乙酯（EC）∶碳酸二甲酯（DMC）∶碳酸甲乙酯（EMC）=1∶1∶8（V/V）电解液作用下，材料反应更加完全、彻底，进而使得首次充电及放电容量分别为331.4 mAh·g-1和233.6 mAh·g-1．

Li-rich layered Li1.18Ni0.15Co0.15Mn0.52O2 were prepared by sol-gel method,and characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）and scanning electron microscope（SEM）, respectively.XRD results shows that the material belongs to layeredα-NaFeO2 structure,XPS confirms that the valence of Ni,Co,Mn was ＋2,＋3 and ＋4,respectively.SEM shows that the material exists as loose micron-sized aggregates,being composed of primary grains with diameter of 200~400 nm.The electrochemistry performance of the material shows similar charge-discharge curves and different capacities at different electrolytes.Especially at the electrolyte with LiPF6 in a mixture of erhylene carbonate（EC）,dimethylcarbonate（DMC） and ethyl methyl carbonate （EMC）with a volume ratio of 1∶1∶8,the material shows a more complete reaction,and the capacity is 331.4 mAh·g-1 and 233 mAh·g-1 at the initial charge and discharge,respectively.