Electronic states in oxidized NaxCoO2 as revealed by X-ray absorption spectroscopy coupled with ab initio calculation

Hideharu Niwa, Kazuyuki Higashiyama, Kaoru Amaha, Wataru Kobayashi, Yutaka Moritomo

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Layered cobalt oxides are promising cathode materials for sodium ion secondary batteries (SIBs). By combined study of the X-ray absorption spectroscopy (XAS) around the O K-edge and ab initio calculation, we investigated the electronic state of the NaxCoO2 with different oxidization state, i.e, in O3-Na0.91CoO2 (CoO2 −0.91) and P2-Na0.66CoO2 (CoO2 −0.66). The O K-edge spectra in the pre-edge (529–536 eV) region shows significant change with oxidization of NaxCoO2. In O3-Na0.91CoO2, the spectra shows an intense band (B band) at 531 eV. In P2-Na0.66CoO2, the spectral weight of the B band increases and a new band (A band) appears at 530 eV. These spectral changes are qualitatively reproduced by the calculated partial density of states (pDOSs) of O3-NaCoO2 and P2-Na1/2CoO2. These results indicate that the electrons are partially removed from the O 2p state with oxidization of NaxCoO2.

Original languageEnglish
Pages (from-to)156-159
Number of pages4
JournalJournal of Power Sources
Volume384
DOIs
Publication statusPublished - 2018 Apr 30
Externally publishedYes

Fingerprint

X ray absorption spectroscopy
Secondary batteries
Electronic states
Cobalt
absorption spectroscopy
Cathodes
Sodium
Ions
Oxides
Electrons
electronics
x rays
storage batteries
cobalt oxides
cathodes
sodium
NaCoO2
cobalt oxide
ions
electrons

Keywords

  • Layered oxides
  • Sodium ion battery
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

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

Cite this

Electronic states in oxidized NaxCoO2 as revealed by X-ray absorption spectroscopy coupled with ab initio calculation. / Niwa, Hideharu; Higashiyama, Kazuyuki; Amaha, Kaoru; Kobayashi, Wataru; Moritomo, Yutaka.

In: Journal of Power Sources, Vol. 384, 30.04.2018, p. 156-159.

Research output: Contribution to journalArticle

Niwa, Hideharu ; Higashiyama, Kazuyuki ; Amaha, Kaoru ; Kobayashi, Wataru ; Moritomo, Yutaka. / Electronic states in oxidized NaxCoO2 as revealed by X-ray absorption spectroscopy coupled with ab initio calculation. In: Journal of Power Sources. 2018 ; Vol. 384. pp. 156-159.
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