Recent debates on the oxygen redox behaviors in battery electrodes have triggered a pressing demand for the reliable detection and understanding of non-divalent oxygen states beyond conventional absorption spectroscopy. Here, enabled by high-efficiency mapping of resonant inelastic X-ray scattering (mRIXS) coupled with first-principles calculations, we report distinct mRIXS features of the oxygen states in Li2O, Li2CO3, and especially, Li2O2, which are successfully reproduced and interpreted theoretically. mRIXS signals are dominated by valence-band decays in Li2O and Li2CO3. However, the oxidized oxygen in Li2O2 leads to partially unoccupied O-2p states that yield a specific intra-band excitonic feature in mRIXS. Such a feature displays a specific emission energy in mRIXS, which disentangles the oxidized oxygen states from the dominating transition-metal/oxygen hybridization features in absorption spectroscopy, thus providing critical hints for both detecting and understanding the oxygen redox reactions in transition-metal oxide based battery materials.
@article{arxiv.1809.08292,
title = {Spectroscopic Signature of Oxidized Oxygen States in Peroxides},
author = {Zengqing Zhuo and Chaitanya Das Pemmaraju and John Vinson and Chunjing Jia and Brian Moritz and Ilkyu Lee and Shawn Sallies and Qinghao Li and Jinpeng Wu and Kehua Dai and Yi-de Chuang and Zahid Hussain and Feng Pan and Thomas P. Devereaux and Wanli Yang},
journal= {arXiv preprint arXiv:1809.08292},
year = {2018}
}
Comments
25 pages, 4 figures, plus 11 pages of Supplementary Information with 4 figures