Off-Stoichiometry in Alluaudite-Type Sodium Iron Sulfate Na2+2xFe2-x(SO4)3 as an Advanced Sodium Battery Cathode Material

Gosuke Oyama, Shin ichi Nishimura, Yuya Suzuki, Masashi Okubo, Atsuo Yamada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)


An alluaudite-type sodium iron sulfate has recently been discovered as a 3.8V cathode material for low-cost, high-power, and efficient sodium-ion batteries. To optimize the composition of the alluaudite phase and to explore further compounds, we have carefully surveyed the Na2SO4-FeSO4 binary system. Solid-state reactions at a moderate temperature of 623K produce two stable phases: 1)vanthoffite-structured Na6Fe(SO4)4 and 2)alluaudite-type Na2+2xFe2-x(SO4)3 with a certain non-stoichiometry. The possible compositional and structural flexibilities demonstrated in this work inspire further improvement of the alluaudite-type sodium metal sulfates for advanced sodium-ion batteries.

Original languageEnglish
Pages (from-to)1019-1023
Number of pages5
Issue number7
Publication statusPublished - 2015 Jul 15
Externally publishedYes


  • Alluaudite
  • High-voltage cathode
  • Nonstoichiometric compounds
  • Sodium iron sulfate
  • Sodium-ion batteries

ASJC Scopus subject areas

  • Catalysis
  • Electrochemistry


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