TY - JOUR
T1 - Molecular Orbital Principles of Oxygen-Redox Battery Electrodes
AU - Okubo, Masashi
AU - Yamada, Atsuo
N1 - Funding Information:
We acknowledge the financial support received from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan; the Grant-in-Aid for Specially Promoted Research no. 15H05701. M.O. was financially supported by the Iketani Science and Technology Foundation. We are grateful to B. Mortemard de Boisse, E. Watanabe, and Y. Harada at the University of Tokyo, D. Asakura at the National Institute of Advanced Industrial Science and Technology, and M. Nakayama at the Nagoya Institute of Technology for their fruitful discussions.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/10/25
Y1 - 2017/10/25
N2 - 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.
AB - 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.
KW - battery
KW - cathode
KW - molecular-orbital method
KW - orphaned oxygen orbital
KW - oxygen-redox reaction
KW - transition-metal oxides
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U2 - 10.1021/acsami.7b09835
DO - 10.1021/acsami.7b09835
M3 - Article
C2 - 29016101
AN - SCOPUS:85032943810
SN - 1944-8244
VL - 9
SP - 36463
EP - 36472
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 42
ER -
