Multiorbital bond formation for stable oxygen-redox reaction in battery electrodes

Takaaki Sudayama,Masashi Okubo,Takahiro Mukai,Tatau Shimada,Masanobu Nakayama,Daisuke Asakura,Kazuki Uehara,Atsuo Yamada,Yoshihisa Harada,Eriko Watanabe,Benoit Mortemard De Boisse,Xiang-Mei Shi,Akihisa Tsuchimoto

doi:10.1039/c9ee04197d

Abstract

Nonbonding oxygen 2p orbitals during oxygen-redox reaction are monitored using resonant inelastic X-ray scattering (RIXS).

Highlights

The use of redox reactions of oxygen in addition to conventional transition-metal redox reactions is an attractive way to increase the capacity of transition-metal oxides.[7]
Oxygen K-edge RIXS spectroscopy was used to examine the existence of p-type localized oxygen 2p orbitals in Li2MnO3, a standard Li-excess layered transition-metal oxide
Oxygen K-edge RIXS spectroscopy records the inelastic scattering during core excitation–relaxation (1s - 2p - 1s), in which the energy loss corresponds to valence excitation between occupied and unoccupied 2p bands.[26]

Summary

Introduction

The use of redox reactions of oxygen in addition to conventional transition-metal redox reactions is an attractive way to increase the capacity of transition-metal oxides.[7] In general, most oxygen 2p orbitals in conventional electrode materials LiMO2 (M: transition metal) form s-type bonds with axial M 3d orbitals (eg orbitals in an Oh symmetry). Research groups led by Bruce and Ceder postulated that oxygen in Li-excess transition-metal oxides Li1+xM1ÀxO2 (Fig. 1a) intrinsically have localized (‘‘orphaned’’) 2p orbital along the Li–O–Li axis without s-type bonding characteristics, which can contribute to an additional oxygen-redox capacity.[10,11]

Methods

Results

Conclusion