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Crystal structure analysis and first principle investigation of F doping in LiFePO4
Ist Teil von
Journal of power sources, 2013-11, Vol.241, p.70-79
Ort / Verlag
Amsterdam: Elsevier B.V
Erscheinungsjahr
2013
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
This work presents the synthesis of F-doped LiFePO4/C composite by the specific modification of the recently suggested synthesis procedure based on an aqueous precipitation of precursor material in molten stearic acid, followed by a high temperature treatment. Besides the lattice parameters and the primitive cell volume reductions, compared to the undoped sample synthesized under the same conditions, the Rietveld refinement also shows that fluorine ions preferably occupy specific oxygen sites. Particularly, the best refinement is accomplished when fluorine ions occupy O(2) sites exclusively. By means of up-to-date electronic structure and total energy calculations this experimental finding is theoretically confirmed. Such fluorine doping also produces closing of the gap in the electronic structure and consequently better conductivity properties of the doped compound. In addition, the morphological and electrochemical performances of the synthesized powder are fully characterized.
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•Nanostructured F-doped LiFePO4/C composite is synthesized.•Structure refinement shows that F ions are solely positioned at O(2) oxygen site.•Theoretical modelings confirmed and support the experimental findings.•Fluorine-doped olivine has finite density of states at the Fermi level.•The powder delivered capacity of 164 mAh g−1.