Role of ligand-to-metal charge transfer in O3-type NaFeO 2-NaNiO2 solid solution for enhanced electrochemical properties

Xianfen Wang, Guandong Liu, Tatsumi Iwao, Masashi Okubo, Atsuo Yamada

Research output: Contribution to journalArticlepeer-review

95 Citations (Scopus)

Abstract

Na-ion batteries have been the subjects of intensive studies for grid-scale energy storage recently. O3-type NaFeO2 is a promising candidate for the Na-ion cathode materials, though the irreversibility during Na-ion extraction/insertion seriously hinders its practical application. The present work demonstrates that partial replacement of Fe in O3-NaFeO2 with Ni leads to the significant improvement of the electrochemical properties. The 57Fe Mössbauer and X-ray absorption spectra show that O3-type NaFeO2-NaNiO2 solid solution forms hybridized frontier orbital of a Fe-O-Ni bond via ligand-to-metal charge transfer, which plays a dominant role in the charge-discharge process. The resulting O3-NaFe 0.3Ni0.7O2 delivers an initial discharge capacity of 135 mA·h·g-1, most of which is in a high-voltage region of 2.5-3.8 V, with a high initial Coulombic efficiency of 93%, and shows enhanced cycle stability.

Original languageEnglish
Pages (from-to)2970-2976
Number of pages7
JournalJournal of Physical Chemistry C
Volume118
Issue number6
DOIs
Publication statusPublished - 2014 Feb 13
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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