期刊
APPLIED SURFACE SCIENCE
卷 371, 期 -, 页码 172-179出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apsusc.2016.02.224
关键词
LiNi0.5Co0.2MnO0.3O2; Fluorine doping; Lithium slab; High voltage; Electrochemical performances
类别
资金
- National Basic Research Program of China (973 Program) [2014CB643406]
- Collaborative Innovation Center of Manganese-Zinc-Vanadium Industrial Technology (Plan of Hunan Province)
A strategy of surface fluorine substitution to enhance the high voltage electrochemical performance of LiNi0.5Co0.2Mn0.3O2 material has been proposed. The inter-slab spacing distance is broaden by fluorine doping, which is deduced from the lattice parameters calculated by Rietveld refinement method. Scanning electron microscopy indicates the fluorine substitution stimulates the growth of the primary particles. Though the initial discharge capacities of LiNi0.5Co0.2Mn0.3O2-zFz (z = 0.02, 0.04, 0.06) is somewhat reduced, the capacity retention under high oxidation state were improved compared to that of bare one. For the optimal composition of LiNi0.5Co0.2Mn0.3O1.98F0.02, it exhibits a capacity retention of 81.1% at 1C after 100 cycles and delivers a discharge capacity of 123.5 mAh g(-1) at 10C, and that of bare sample are just 70.1% and 109.6 mAh g(-1), respectively. Cyclic voltammetry and electron impedance spectroscopy measurements demonstrate that the fluorine doping could significantly lower the cell polarization and retard the impedance rise. Transmission electron microscope analysis of cycled electrodes is also performed and it implies that fluorine substitution can effectively safeguard the electrode from HF erosion to maintain the bulk structural stable permanently. (C) 2016 Elsevier B.V. All rights reserved.
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