The LiV 0.96 Mn 0.04 PO 4 F/C composite was prepared by partial substitution of vanadium with manganese and in situ carbon coating of LiVPO 4 F via a 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 4 F, X-ray photoelectron spectroscopy (XPS) indicates the co-existence of Mn 3+ and Mn 4+ . With $6.29 wt% residual carbon (estimated by thermogravimetric analysis, TGA) included, the specific discharge capacity of LiV 0.96 Mn 0.04 PO 4 F/C at 0.1 C and 6 C could reach 138 mA h g À1 and 98 mA h g À1 , 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 ct ) is significantly reduced by Mn substitution, and the lithium diffusion coefficient was calculated to be 1.34 Â 10 À13 cm 2 s À1 , which is an order of magnitude higher than that of pristine LiVPO 4 F/C. Moreover, LiV 0.96 Mn 0.04 PO 4 F/C retains 74% of its initial capacity after 500 cycles at 1 C at 65 C, indicating its potential application at high temperatures.
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