Molecular Orbital Principles of Oxygen-Redox Battery Electrodes

Masashi Okubo, Atsuo Yamada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Citations (Scopus)

Abstract

Lithium-ion batteries are key energy-storage devices for a sustainable society. The most widely used positive electrode materials are LiMO2 (M: transition metal), in which a redox reaction of M occurs in association with Li+ (de)intercalation. Recent developments of Li-excess transition-metal oxides, which deliver a large capacity of more than 200 mAh/g using an extra redox reaction of oxygen, introduce new possibilities for designing higher energy density lithium-ion batteries. For better engineering using this fascinating new chemistry, it is necessary to achieve a full understanding of the reaction mechanism by gaining knowledge on the chemical state of oxygen. In this review, a summary of the recent advances in oxygen-redox battery electrodes is provided, followed by a systematic demonstration of the overall electronic structures based on molecular orbitals with a focus on the local coordination environment around oxygen. We show that a π-type molecular orbital plays an important role in stabilizing the oxidized oxygen that emerges upon the charging process. Molecular orbital principles are convenient for an atomic-level understanding of how reversible oxygen-redox reactions occur in bulk, providing a solid foundation toward improved oxygen-redox positive electrode materials for high energy-density batteries.

Original languageEnglish
Pages (from-to)36463-36472
Number of pages10
JournalACS Applied Materials and Interfaces
Volume9
Issue number42
DOIs
Publication statusPublished - 2017 Oct 25
Externally publishedYes

Keywords

  • battery
  • cathode
  • molecular-orbital method
  • orphaned oxygen orbital
  • oxygen-redox reaction
  • transition-metal oxides

ASJC Scopus subject areas

  • Materials Science(all)

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