Unraveling Oxygen Evolution in Li-Rich Oxides: A Unified Modeling of the Intermediate Peroxo/Superoxo-like Dimers

Zhenlian Chen, Jun Li, Xiao Cheng Zeng

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Peroxo/superoxo is a key intermediate in oxygen evolution/reduction reactions in (electro)catalysis. However, peroxo/superoxo analogues have aroused controversies relevant to the origin of oxygen-anion redox. Specifically, some characteristics such as the magnitude of the O-O bond length in bulk materials have been puzzling during oxygen oxidation, as has the relationship between the peroxo/superoxo intermediate and the release of oxygen. The latter is a major safety concern to the application of oxygen-anion redox in lithium ion batteries. Herein, we present a unified modeling of the full delithiation process for model system Li2MnO3 by using first-principles calculations. We find that the cationic antisite defects and the electron deficiency are two major limiting factors in the anionic oxidation whose state can evolve, as the degree of delithiation increases, from the electron/hole, through peroxo-like O2?- dimer formation, to the eventual release of gas-phase oxygen molecule. During the delithiation process, the dangling oxygen (i.e., singly coordinated with Mn) pairs play a critical role in intermediate dimer formation. Meanwhile, we identify five generic binding patterns of O2?- dimers with Mn ions for which the O-O bond length varies from 1.45 Å in the peroxo state to 1.22 Å in the gas-phase oxygen molecule. Moreover, the dominant features of the three molecular orbitals, σc, ?a, and ?b, are distinguished, with the corresponding energy levels being highly delocalized and mixed as a result of the interplay with the host lattice. This work provides a deep understanding of the intermediate states of the anionic redox and suggests new strategies that mitigate oxygen release for the design of highly efficient and safe Li-rich cathode materials.

Original languageEnglish (US)
Pages (from-to)10751-10759
Number of pages9
JournalJournal of the American Chemical Society
Volume141
Issue number27
DOIs
StatePublished - Jul 10 2019

Fingerprint

Dimers
Oxides
Oxygen
Oxidation-Reduction
Bond length
Anions
Negative ions
Gases
Electrons
Ions
Oxidation
Molecules
Molecular orbitals
Catalysis
Lithium
Electron energy levels
Electrodes
Cathodes
Safety
Defects

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Unraveling Oxygen Evolution in Li-Rich Oxides : A Unified Modeling of the Intermediate Peroxo/Superoxo-like Dimers. / Chen, Zhenlian; Li, Jun; Zeng, Xiao Cheng.

In: Journal of the American Chemical Society, Vol. 141, No. 27, 10.07.2019, p. 10751-10759.

Research output: Contribution to journalArticle

@article{dd78dfd2d52c4c139784ae2ab726da9e,
title = "Unraveling Oxygen Evolution in Li-Rich Oxides: A Unified Modeling of the Intermediate Peroxo/Superoxo-like Dimers",
abstract = "Peroxo/superoxo is a key intermediate in oxygen evolution/reduction reactions in (electro)catalysis. However, peroxo/superoxo analogues have aroused controversies relevant to the origin of oxygen-anion redox. Specifically, some characteristics such as the magnitude of the O-O bond length in bulk materials have been puzzling during oxygen oxidation, as has the relationship between the peroxo/superoxo intermediate and the release of oxygen. The latter is a major safety concern to the application of oxygen-anion redox in lithium ion batteries. Herein, we present a unified modeling of the full delithiation process for model system Li2MnO3 by using first-principles calculations. We find that the cationic antisite defects and the electron deficiency are two major limiting factors in the anionic oxidation whose state can evolve, as the degree of delithiation increases, from the electron/hole, through peroxo-like O2?- dimer formation, to the eventual release of gas-phase oxygen molecule. During the delithiation process, the dangling oxygen (i.e., singly coordinated with Mn) pairs play a critical role in intermediate dimer formation. Meanwhile, we identify five generic binding patterns of O2?- dimers with Mn ions for which the O-O bond length varies from 1.45 {\AA} in the peroxo state to 1.22 {\AA} in the gas-phase oxygen molecule. Moreover, the dominant features of the three molecular orbitals, σc, ?a, and ?b, are distinguished, with the corresponding energy levels being highly delocalized and mixed as a result of the interplay with the host lattice. This work provides a deep understanding of the intermediate states of the anionic redox and suggests new strategies that mitigate oxygen release for the design of highly efficient and safe Li-rich cathode materials.",
author = "Zhenlian Chen and Jun Li and Zeng, {Xiao Cheng}",
year = "2019",
month = "7",
day = "10",
doi = "10.1021/jacs.9b03710",
language = "English (US)",
volume = "141",
pages = "10751--10759",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "27",

}

TY - JOUR

T1 - Unraveling Oxygen Evolution in Li-Rich Oxides

T2 - A Unified Modeling of the Intermediate Peroxo/Superoxo-like Dimers

AU - Chen, Zhenlian

AU - Li, Jun

AU - Zeng, Xiao Cheng

PY - 2019/7/10

Y1 - 2019/7/10

N2 - Peroxo/superoxo is a key intermediate in oxygen evolution/reduction reactions in (electro)catalysis. However, peroxo/superoxo analogues have aroused controversies relevant to the origin of oxygen-anion redox. Specifically, some characteristics such as the magnitude of the O-O bond length in bulk materials have been puzzling during oxygen oxidation, as has the relationship between the peroxo/superoxo intermediate and the release of oxygen. The latter is a major safety concern to the application of oxygen-anion redox in lithium ion batteries. Herein, we present a unified modeling of the full delithiation process for model system Li2MnO3 by using first-principles calculations. We find that the cationic antisite defects and the electron deficiency are two major limiting factors in the anionic oxidation whose state can evolve, as the degree of delithiation increases, from the electron/hole, through peroxo-like O2?- dimer formation, to the eventual release of gas-phase oxygen molecule. During the delithiation process, the dangling oxygen (i.e., singly coordinated with Mn) pairs play a critical role in intermediate dimer formation. Meanwhile, we identify five generic binding patterns of O2?- dimers with Mn ions for which the O-O bond length varies from 1.45 Å in the peroxo state to 1.22 Å in the gas-phase oxygen molecule. Moreover, the dominant features of the three molecular orbitals, σc, ?a, and ?b, are distinguished, with the corresponding energy levels being highly delocalized and mixed as a result of the interplay with the host lattice. This work provides a deep understanding of the intermediate states of the anionic redox and suggests new strategies that mitigate oxygen release for the design of highly efficient and safe Li-rich cathode materials.

AB - Peroxo/superoxo is a key intermediate in oxygen evolution/reduction reactions in (electro)catalysis. However, peroxo/superoxo analogues have aroused controversies relevant to the origin of oxygen-anion redox. Specifically, some characteristics such as the magnitude of the O-O bond length in bulk materials have been puzzling during oxygen oxidation, as has the relationship between the peroxo/superoxo intermediate and the release of oxygen. The latter is a major safety concern to the application of oxygen-anion redox in lithium ion batteries. Herein, we present a unified modeling of the full delithiation process for model system Li2MnO3 by using first-principles calculations. We find that the cationic antisite defects and the electron deficiency are two major limiting factors in the anionic oxidation whose state can evolve, as the degree of delithiation increases, from the electron/hole, through peroxo-like O2?- dimer formation, to the eventual release of gas-phase oxygen molecule. During the delithiation process, the dangling oxygen (i.e., singly coordinated with Mn) pairs play a critical role in intermediate dimer formation. Meanwhile, we identify five generic binding patterns of O2?- dimers with Mn ions for which the O-O bond length varies from 1.45 Å in the peroxo state to 1.22 Å in the gas-phase oxygen molecule. Moreover, the dominant features of the three molecular orbitals, σc, ?a, and ?b, are distinguished, with the corresponding energy levels being highly delocalized and mixed as a result of the interplay with the host lattice. This work provides a deep understanding of the intermediate states of the anionic redox and suggests new strategies that mitigate oxygen release for the design of highly efficient and safe Li-rich cathode materials.

UR - http://www.scopus.com/inward/record.url?scp=85069327610&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85069327610&partnerID=8YFLogxK

U2 - 10.1021/jacs.9b03710

DO - 10.1021/jacs.9b03710

M3 - Article

C2 - 31251049

AN - SCOPUS:85069327610

VL - 141

SP - 10751

EP - 10759

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 27

ER -