Electronic structural changes of the electrochemically delithiated LiFe0.5Co0.5PO4 cathode material studied by X-ray absorption spectroscopy

Won Sub Yoon, Kyung Yoon Chung, Kyung Wan Nam, James McBreen, Deyu Wang, Xuejie Huang, Hong Li, Liquan Chen, Xiao Qing Yang

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22 Scopus citations

Abstract

In order to study the electronic structure changes of the electrochemically delithiated Li1-xFe0.5Co0.5PO4 system, in situ Fe and Co K-edge XAS and ex situ P K-edge XAS have been carried out during the first charging process. The Fe and Co K-edge XAS results showed that the major charge compensation at the metal sites during charge is achieved by the oxidation of Fe2+ ions at lower potential plateau (∼3.6 V) and the oxidation of Co2+ ions at higher potential plateau (∼5.0 V). The gradual shift of main edge features in P K-edge XANES spectra showed that P{single bond}O bonds become less covalent during delithiation, due to the increased covalency of Fe3+{single bond}O bonds via the inductive effect. From the observation of pre-edge peaks, it is concluded that the electrochemical delithiation of Li1-xFePO4 result in the hybridization of P 3p states with the metal 3d states.

Original languageEnglish
Pages (from-to)427-430
Number of pages4
JournalJournal of Power Sources
Volume183
Issue number1
DOIs
StatePublished - 15 Aug 2008

Keywords

  • LiFeCoPO
  • Lithium rechargeable batteries
  • X-ray absorption spectroscopy
  • XAS

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