Irreversible phase transition between LiFePO4 and FePO4 during high-rate charge-discharge reaction by operando X-ray diffraction

Ikuma Takahashi, Takuya Mori, Takahiro Yoshinari, Yuki Orikasa, Yukinori Koyama, Haruno Murayama, Katsutoshi Fukuda, Masaharu Hatano, Hajime Arai, Yoshiharu Uchimoto, Takayuki Terai

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


LiFePO4 is a practically used cathode material for lithium-ion batteries due to a high theoretical capacity, high cycle capability and the high-rate performance. The metastable LixFePO4 (LxFP) phase with an intermediate composition appears in the non-equilibrium state at high-rate condition. However, the formation process of the metastable LxFP phase and its impact to the electrochemical property are still unclear. In order to elucidate these points, we directly observed the phase transition behavior by applying operando XRD during 10C charge-discharge. LxFP phase does not form in charge reaction but preferentially forms in discharge reaction. The phase transition from LxFP to Li-rich phase is less likely to proceed in the end of discharge reaction. The asymmetric phase transition between LiFePO4 and FePO4 results in decreasing the discharge capacity and increasing the irreversible capacity at high-rate conditions.

Original languageEnglish
Pages (from-to)122-126
Number of pages5
JournalJournal of Power Sources
Publication statusPublished - Mar 31 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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