Cathode properties of Na3M2(PO4) 2F3 [M = Ti, Fe, V] for sodium-ion batteries

Kuniko Chihara, Ayuko Kitajou, Irina D. Gocheva, Shigeto Okada, Jun Ichi Yamaki

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178 Citations (Scopus)


The compounds Na3M2(PO4)2F 3 [M = Ti, Fe, V] were obtained by two-step solid-state synthesis, and its electrochemical properties as cathode active materials of sodium-ion batteries were investigated. The obtained Na3M2(PO 4)2F3 materials were found to have a tetragonal structure with a space group, P42/mnm, and were isostructural with β-Na3V2(PO4)2F3 by X-ray powder diffraction (XRD) measurements. Within this series, Na 3V2(PO4)2F3 in particular exhibited stability on cycling and a capacity of approximately 120 mAh g -1 against sodium metal. Capacity retention for this compound was 98%, even after the 40th cycle of prolonged charge/discharge measurements. Ex-situ XRD data for Na3V2(PO4) 2F3 electrodes charged and discharged at selected voltages showed that the material structure expanded along the c axis during charging up to 4.3 V and returned to its original dimensions after cycling. This is attributed to the extraction/insertion of Na atoms layers along the (002) a-b plane in the tetragonal structure.

Original languageEnglish
Pages (from-to)80-85
Number of pages6
JournalJournal of Power Sources
Publication statusPublished - 2013

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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