High performance LiV sub(0.96)Mn sub(0.04)PO sub(4)F/C cathodes for lithium-ion batteries

The LiV sub(0.96)Mn sub(0.04)PO sub(4)F/C composite was prepared by partial substitution of vanadium with manganese and in situcarbon coating of LiVPO sub(4)F viaa modified carbothermal reduction route. Rietveld refinement of X-ray diffraction (XRD) patterns shows that the crystalline lattice is sma...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2013-01, Vol.1 (7), p.2501-2507
Main Authors: Sun, Xiaofei, Xu, Youlong, Jia, Mingrui, Ding, Peng, Liu, Yanghao, Chen, Kai
Format: Article
Language:English
Subjects:
Carbon
Electrochemical impedance spectroscopy
Electron energy loss spectroscopy
Lithium
Lithium-ion batteries
Manganese
Sustainability
X-ray photoelectron spectroscopy
X-rays
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Summary:The LiV sub(0.96)Mn sub(0.04)PO sub(4)F/C composite was prepared by partial substitution of vanadium with manganese and in situcarbon coating of LiVPO sub(4)F viaa modified carbothermal reduction route. Rietveld refinement of X-ray diffraction (XRD) patterns shows that the crystalline lattice is smaller than the value reported in the literature. While electron energy loss spectroscopy (EELS) on a selected area of high resolution transmission electron microscopy (HRTEM) demonstrates that Mn is successfully doped into LiVPO sub(4)F, X-ray photoelectron spectroscopy (XPS) indicates the co-existence of Mn super(3+) and Mn super(4+). With similar to 6.29 wt% residual carbon (estimated by thermogravimetric analysis, TGA) included, the specific discharge capacity of LiV sub(0.96)Mn sub(0.04)PO sub(4)F/C at 0.1 C and 6 C could reach 138 mA h g super(-1) and 98 mA h g super(-1), respectively. The capacity retention after 1000 cycles at 1 C is about 90%, corresponding to only 0.01% loss per cycle. Electrochemical impedance spectroscopy (EIS) shows that the charge transfer resistance (R sub(ct)) is significantly reduced by Mn substitution, and the lithium diffusion coefficient was calculated to be 1.34 10 super(-13) cm super(2) s super(-1), which is an order of magnitude higher than that of pristine LiVPO sub(4)F/C. Moreover, LiV sub(0.96)Mn sub(0.04)PO sub(4)F/C retains 74% of its initial capacity after 500 cycles at 1 C at 65 degree C, indicating its potential application at high temperatures.
ISSN:2050-7488
2050-7496
DOI:10.1039/c2ta01338j