AlF3包覆锂离子电池正极材料Li1.2(Mn0.54Ni0.16Co0.08)O2的制备、表征及电化学性能（英文）

采用溶胶-凝胶法合成锂离子电池正极材料Li1.2(Mn0.54Ni0.16Co0.08)O2,并用Al F3对这种材料进行表面包覆改性。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨率透射电子显微镜(HRTEM)等表征材料的结构和形貌。结果表明,合成的Li1.2(Mn0.54Ni0.16Co0.08)O2具有典型的层状α-Na Fe O2结构,AlF3均匀包覆在Li1.2(Mn0.54Ni0.16Co0.08)O2材料表面,包覆层厚度为5~7 nm。电化学测试表明,包覆Al F3后材料的电化学性能得到提高,在1C倍率下,包覆的AlF3材料的首次放电容量为208.2 m A·h/g,50次循环后容量保持率为72.4%,而未包覆AlF3的材料的首次放电容量和容量保持率分别为191.7 m A·h/g和51.6%。

Synthesis,characterization and electrochemical performance of AlF3-coated Li1.2(Mn0.54Ni0.16Co0.08)O2 as cathode for Li-ion battery

Li-rich layered transitional metal oxide Li_1.2(Mn_0.54Ni_0.16Co_0.08)O₂ was prepared by sol—gel method and further modified by AlF₃ coating via a wet process. The bare and AlF₃-coated Li_1.2(Mn_0.54Ni_0.16Co_0.08)O₂ samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and high resolution transmission electron microscope (HRTEM). XRD results show that the bare and AlF₃-coated samples have typical hexagonal α-NaFeO₂ structure, and AlF₃-coated layer does not affect the crystal structure of the bare Li_1.2(Mn_0.54Ni_0.16Co_0.08)O₂. Morphology measurements present that the AlF₃ layer with a thickness of 5—7 nm is coated on the surface of the Li_1.2(Mn_0.54Ni_0.16Co_0.08)O₂ particles. Galvanostatic charge—discharge tests at various rates show that the AlF₃-coated Li_1.2(Mn_0.54Ni_0.16Co_0.08)O₂ has an enhanced electrochemical performance compared with the bare sample. At 1C rate, it delivers an initial discharge capacity of 208.2 mA·h/g and a capacity retention of 72.4% after 50 cycles, while those of the bare Li_1.2(Mn_0.54Ni_0.16Co_0.08)O₂ are 191.7 mA·h/g and 51.6 %, respectively.