Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7740561 | Journal of Power Sources | 2013 | 6 Pages |
Abstract
V-substituted LiFePO4 (LiFe1âxVxPO4, 0 â¤Â x â¤Â 0.10) powders are prepared via a solution method. The compositions, crystalline structure, morphology of the prepared powders are systemically investigated with inductive couple plasma-option emission spectrometry (ICP-OES), synchrotron radiation X-ray diffraction (s-XRD), X-ray Absorption Spectroscopy (XAS) and field emission-transmission electron microscopy (FE-TEM). Results of s-XRD and Rietveld analysis reveal that olivine phase is observed exclusively for LiFe1âxVxPO4 (x â¤Â 0.05) samples, whereas a minor amount of monoclinic Li3V2(PO4)3 is detected in the prepared LiFe0.93V0.07PO4 and LiFe0.90V0.10PO4 samples. It is also found that the lattice parameters of olivine structure and average Li-O and M-O (M = Fe or V) bond lengths slightly increase and decrease with the amount of V substitution, recommending an enhanced lithium diffusivity in the structure. Results of XAS study suggest that V ions occupy octahedral sites (4c) of Fe in LiFePO4 structure with valence of 3+, showing good agreement with shortened M-O bonds determined in Rietveld analysis. As a result of V substitution, LiFe1âxVxPO4, (0 â¤Â x â¤Â 0.10) cathodes exhibit better electrochemical performance, such as discharge capacity, rate capability, and cycling performance at both room and elevated temperatures.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
Mao-Sung Chen, She-huang Wu, Wei Kong Pang,