Oxygen redox in hexagonal layered Na: XTMO3 (TM = 4d elements) for high capacity Na ion batteries

M. H.N. Assadi, Masashi Okubo, Atsuo Yamada, Yoshitaka Tateyama

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Through comprehensive density functional calculations, we demonstrate oxygen's significant participation in the redox reaction in a Na excess NaxRuO3 cathode material. The availability of O electrons for the redox reaction originates from the local coordination environment. For high sodium content (x ≈ 2), O ions in the layered hexagonal Na2RuO3 compound are coordinated by four Na ions and consequently have their 2p electrons lifted closer to the Fermi level. For lower Na content (x ≈ 1), Na1RuO3 adopts an ilmenite type R3 structure in which O ions are coordinated by two Ru and two Na ions. In this case, O under-coordination further elevates O 2p states closer to the Fermi level. In both cases, high O electronic population near the Fermi level facilitates continuous participation of O in the redox reaction over a wide range of Na concentrations. Based on this concept, we also predict that Na1NbO3 with an ilmenite framework is a suitable and economical candidate for high voltage and high capacity cathodes for Na ion batteries.

Original languageEnglish
Pages (from-to)3747-3753
Number of pages7
JournalJournal of Materials Chemistry A
Volume6
Issue number8
DOIs
Publication statusPublished - 2018
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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