Intercalation of sodium ions into hollow iron oxide nanoparticles

Bonil Koo, Soma Chattopadhyay, Tomohiro Shibata, Vitali B. Prakapenka, Christopher S. Johnson, Tijana Rajh, Elena V. Shevchenko

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


Cation vacancies in hollow γ-Fe2O3 nanoparticles are utilized for efficient sodium ion transport. As a result, fast rechargeable cathodes can be assembled from Earth-abundant elements such as iron oxide and sodium. We monitored in situ structural and electronic transformations of hollow iron oxide nanoparticles by synchrotron X-ray adsorption and diffraction techniques. Our results revealed that the cation vacancies in hollow γ-Fe2O3 nanoparticles can serve as hosts for sodium ions in high voltage range (4.0-1.1 V), allowing utilization of γ-Fe2O3 nanoparticles as a cathode material with high capacity (up to 189 mAh/g), excellent Coulombic efficiency (99.0%), good capacity retention, and superior rate performance (up to 99 mAh/g at 3000 mA/g (50 C)). The appearance of the capacity at high voltage in iron oxide that is a typical anode and the fact that this capacity is comparable with the capacities observed in typical cathodes emphasize the importance of the proper understanding of the structure-properties correlation. In addition to that, encapsulation of hollow γ-Fe2O3 nanoparticles between two layers of carbon nanotubes allows fabrication of lightweight, binder-free, flexible, and stable electrodes. We also discuss the effect of electrolyte salts such as NaClO4 and NaPF6 on the Coulombic efficiency at different cycling rates.

Original languageEnglish (US)
Pages (from-to)245-252
Number of pages8
JournalChemistry of Materials
Issue number2
StatePublished - Jan 22 2013
Externally publishedYes


  • cation vacancy
  • fast rechargeable cathode
  • hollow nanoparticle
  • in situ study
  • iron oxide
  • sodium ion battery

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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