@article{a219fa3580e140e0a41d323e730d90cd,
title = "Multiorbital bond formation for stable oxygen-redox reaction in battery electrodes",
abstract = "High-energy-density batteries have been a long-standing target toward sustainability, but the energy density of state-of-the-art lithium-ion batteries is limited in part by the small capacity of the positive electrode materials. Although employing the additional oxygen-redox reaction of Li-excess transition-metal oxides is an attractive approach to increase the capacity, an atomic-level understanding of the reaction mechanism has not been established so far. Here, using bulk-sensitive resonant inelastic X-ray scattering spectroscopy combined with ab initio computations, we demonstrate the presence of a localized oxygen 2p orbital weakly hybridized with transition metal t2g orbitals that was theoretically predicted to play a key role in oxygen-redox reactions. After oxygen oxidation, the hole in the oxygen 2p orbital is stabilized by the generation of either a (σ + π) multiorbital bond through strong π back-donation or peroxide O22- through oxygen dimerization. The multiorbital bond formation with σ-accepting and π-donating transition metals can thus lead to reversible oxygen-redox reaction.",
author = "Takaaki Sudayama and Kazuki Uehara and Takahiro Mukai and Daisuke Asakura and Shi, {Xiang Mei} and Akihisa Tsuchimoto and {Mortemard De Boisse}, Benoit and Tatau Shimada and Eriko Watanabe and Yoshihisa Harada and Masanobu Nakayama and Masashi Okubo and Atsuo Yamada",
note = "Funding Information: This work was financially supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan; Grant-in-Aid for Specially Promoted Research No. 15H05701 and the {"}Elemental Strategy Initiative for Catalysis and Batteries{"} (ESICB). M. O. was financially supported by JSPS KAKENHI Grant Number 19H05816, 18K19124, and the Iketani Science and Technology Foundation. The RIXS spectroscopy was performed by the joint research in Synchrotron Radiation Research Organization and the Institute for Solid State Physics, the University of Tokyo (Proposal No. 2019B7456, 2019A7452, 2018B7590, 2018A7560, 2017B7540, 2017A7525, 2016B7516 and 2015B7500). We also thank the Information Technology Center of Nagoya University for providing computing resources (CX400 and FX400). M. N. was supported by {"}Materials Research by Information Integration{"} Initiative (MI2I) project of the Support Program for Starting Up Innovation Hub from Japan Science and Technology Agency (JST), and JSPS KAKENHI Grant Number 19H05815. We are grateful to J. Miyawaki at the University of Tokyo for his support to the RIXS measurements. Funding Information: This work was financially supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan; Grant-in-Aid for Specially Promoted Research No. 15H05701 and the {\textquoteleft}{\textquoteleft}Elemental Strategy Initiative for Catalysis and Batteries{\textquoteright}{\textquoteright} (ESICB). M. O. was financially supported by JSPS KAKENHI Grant Number 19H05816, 18K19124, and the Iketani Science and Technology Foundation. The RIXS spectroscopy was performed by the joint research in Synchrotron Radiation Research Organization and the Institute for Solid State Physics, the University of Tokyo (Proposal No. 2019B7456, 2019A7452, 2018B7590, 2018A7560, 2017B7540, 2017A7525, 2016B7516 and 2015B7500). We also thank the Information Technology Center of Nagoya University for providing computing resources (CX400 and FX400). M. N. was supported by {\textquoteleft}{\textquoteleft}Materials Research by Information Integration{\textquoteright}{\textquoteright} Initiative (MI2I) project of the Support Program for Starting Up Innovation Hub from Japan Science and Technology Agency (JST), and JSPS KAKENHI Grant Number 19H05815. We are grateful to J. Miyawaki at the University of Tokyo for his support to the RIXS measurements. Publisher Copyright: {\textcopyright} The Royal Society 2020 of Chemistry.",
year = "2020",
doi = "10.1039/c9ee04197d",
language = "English",
volume = "13",
pages = "1492--1500",
journal = "Energy and Environmental Science",
issn = "1754-5692",
publisher = "Royal Society of Chemistry",
number = "5",
}