The phase transition behaviors of Li1-xMn0.5Fe0.5PO4 during lithium extraction studied by in situ X-ray absorption and diffraction techniques

Kyung Wan Nam, Won Sub Yoon, Karim Zaghib, Kyung Yoon Chung, Xiao Qing Yang

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

How the structural changes take place in LiMnyFe1-yPO4-type cathode materials during lithium extraction/insertion is an important issue, especially on if they go through the single-phase reaction (i.e., solid solution reaction) or the two-phase reaction regions. Here we report the studies on the phase transition behaviors of a carbon coated Li1-xMn0.5Fe0.5PO4 (C{single bond}Li1-xMn0.5Fe0.5PO4, 0.0 ≤ x ≤ 1.0) sample during the first charge using in situ X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques. The combination of in situ XAS and XRD results clearly identify two two-phase coexistence regions at two voltage plateaus of 3.6 (Fe2+/Fe3+) and 4.2 V (Mn2+/Mn3+) and a narrow intermediate region which proceeds via single-phase reaction in between two two-phase regions. In addition, simultaneous redox reactions of Fe2+/Fe3+ and Mn2+/Mn3+ in the narrow single-phase region are reported and discussed for the first time.

Original languageEnglish
Pages (from-to)2023-2026
Number of pages4
JournalElectrochemistry Communications
Volume11
Issue number10
DOIs
StatePublished - Oct 2009

Keywords

  • LiFePO
  • Lithium-ion batteries
  • Olivine structure
  • Solid solution mechanism
  • X-ray absorption near edge structure

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