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.pdfVIP

Trans. Nonferrous Met. Soc. China 24(2014) 3534−3540 Synthesis, characterization and electrochemical performance of AlF3-coated Li1.2(Mn0.54Ni0.16Co0.08)O2 as cathode for Li-ion battery Yan LI, Kai-yu LIU, Mei-yu LÜ, Lai WEI, Jian-jian ZHONG School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China Received 27 November 2013; accepted 12 May 2014 Abstract: Li-rich layered transitional metal oxide Li1.2(Mn0.54Ni0.16Co0.08)O2 was prepared by sol−gel method and further modified by AlF3 coating via a wet process. The bare and AlF3-coated Li1.2(Mn0.54Ni0.16Co0.08)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 Li1.2(Mn0.54Ni0.16Co0.08)O2. Morphology measurements present that the AlF3 layer with a thickness of 5−7 nm is coated on the surface of the Li1.2(Mn0.54Ni0.16Co0.08)O2 particles. Galvanostatic charge−discharge tests at various rates show that the AlF3-coated Li1.2(Mn0.54Ni0.16Co0.08)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 Li1.2(Mn0.54Ni0.16Co0.08)O2 are 191.7 mA·h/g and 51.6 %, respectively. Key words: lithium-ion battery; Li1.2(Mn0.54Ni0.16Co0.08)O2; AlF3 surface coating; capacity retention 1 Introduction In order to meet the requirement for electric vehicles (EVs) or hybrid electric vehicles (HEVs), lower cost, higher capacity an