Li_(1.2)Mn_(0.54)Co_(0.13)Ni_(0.13)O_2@V_2O_5核壳复合材料的制备及其电化学性能

Preparation of Li_(1.2)Mn_(0.54)Co_(0.13)Ni_(0.13)O_2@V_2O_5 Core-shell Composite and Its Electrochemical Properties

采用溶胶-凝胶技术在富锂锰基固溶体Li1.2Mn0.54Co0.13Ni0.13O2表面包覆V2O5,制备了Li1.2Mn0.54Co0.13Ni0.13O2@V2O5核壳复合材料。通过扫描电镜(SEM)和透射电镜(TEM)观察其形貌,X射线衍射(XRD)分析确定其结构。结果显示,结晶态的V2O5均匀包覆在类球形Li1.2Mn0.54Co0.13Ni0.13O2颗粒表面,Li1.2Mn0.54Co0.13Ni0.13O2材料的晶体结构在包覆前后保持不变。X射线光电子能谱(XPS)分析结果表明,该核壳复合材料首次充电时,锂离子嵌入V2O5包覆层。电化学测试结果表明,表面包覆15%V2O5的核壳复合材料具有最佳的电化学性能:0.1C倍率下放电比容量为276 mAh/g,首次充放电库仑效率达到94%,50次循环后容量保持率达89%。

Li1.2Mn0.54Co0.13Ni0.13O2@V2O5 core-shell composite was prepared by coating V2O5 on the surface of the lithium-rich manganese-based solid solution Li1.2Mn0.54Co0.13Ni0.13O2 particles through Sol-Gel technology. Its morphology was observed by using scanning electronic microscope （SEM） and transition electronic microscope （TEM） while the crystal structure was calculated from the results of the X-ray diffraction （XRD）. It is found that the quasi spherical core-shell composite is coated homogeneously with the crystalline V2O5 nanoparticles. The crystal structure of Li1.2Mn0.54Co0.13Ni0.13O2 core is maintained after the surface coating. XPS spectra suggest that Li^＋ ions intercalate the crystal structure of the V2O5 shell during the first charge. The electrochemical measurements show that the core-shell composite being coated with 15% V2O5 could deliver an initial capacity of 276 mAh/g at the rate of 0.1C accompamied by a coulombic efficiency of 94%. It can remain 89% of the initial capacity after 50 charge/discharge cycles.