Direct observation of a metastable crystal phase of LixFePO 4 under electrochemical phase transition

Yuki Orikasa, Takehiro Maeda, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, Hajime Tanida, Hajime Arai, Eiichiro Matsubara, Yoshiharu Uchimoto, Zempachi Ogumi

Research output: Contribution to journalArticlepeer-review

148 Citations (Scopus)


The phase transition between LiFePO4 and FePO4 during nonequilibrium battery operation was tracked in real time using time-resolved X-ray diffraction. In conjunction with increasing current density, a metastable crystal phase appears in addition to the thermodynamically stable LiFePO 4 and FePO4 phases. The metastable phase gradually diminishes under open-circuit conditions following electrochemical cycling. We propose a phase transition path that passes through the metastable phase and posit the new phase's role in decreasing the nucleation energy, accounting for the excellent rate capability of LiFePO4. This study is the first to report the measurement of a metastable crystal phase during the electrochemical phase transition of LixFePO4.

Original languageEnglish
Pages (from-to)5497-5500
Number of pages4
JournalJournal of the American Chemical Society
Issue number15
Publication statusPublished - Apr 17 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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