Local electronic structure of olivine phases of LixFePO 4

Shu Miao, Michael Kocher, Peter Rez, Brent Fultz, Rachid Yazami, Channing C. Ahn

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28 Scopus citations

Abstract

Changes in the local electronic structure at atoms around Li sites in the olivine phase of LiFePO4 were studied during delithiation. Electron energy loss spectrometry was used for measuring shifts and intensities of the near-edge structure at the K-edge of O and at the L-edges of P and Fe. Electronic structure calculations were performed on these materials with a plane-wave pseudopotential code and with an atomic multiplet code with crystal fields. It is found that both Fe and O atoms accommodate some of the charge around the Li+ ion, evidently in a hybridized Fe-O state. The O 2p levels appear to be fully occupied at the composition LiFePO4. With delithiation, however, these states are partially emptied, suggestive of a more covalent bonding to the oxygen atom in FePO4 as compared to LiFePO4. The same behavior is found for the white lines at the Fe L2,3-edges, which also undergo a shift in energy upon delithiation. A charge transfer of up to 0.48 electrons is found at the Fe atoms, as determined from white line intensity variations after delithiation, while the remaining charge is compensated by O atoms. No changes are evident at the P L 2,3-edges.

Original languageEnglish (US)
Pages (from-to)4242-4247
Number of pages6
JournalJournal of Physical Chemistry A
Volume111
Issue number20
DOIs
StatePublished - May 24 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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    Miao, S., Kocher, M., Rez, P., Fultz, B., Yazami, R., & Ahn, C. C. (2007). Local electronic structure of olivine phases of LixFePO 4. Journal of Physical Chemistry A, 111(20), 4242-4247. https://doi.org/10.1021/jp068605q