Towards controlling the reversibility of anionic redox in transition metal oxides for high-energy Li-ion positive electrodes
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Author(s)
Yu, Yang
Karayaylali, Pinar
Sokaras, Dimosthenis
Giordano, Livia
Kou, Ronghui
Sun, Cheng-Jun
Maglia, Filippo
Jung, Roland
Gittleson, Forrest S.
Shao-Horn, Yang
Date Issued
February 2021
Journal
Energy & Environmental Science
Publisher
Royal Society of Chemistry (RSC)
Citation
Yu, Yang et al. "Towards controlling the reversibility of anionic redox in transition metal oxides for high-energy Li-ion positive electrodes." Energy & Environmental Science 14, 4 (February 2021): 2322-2334. © 2021 The Royal Society of Chemistry
Abstract
Anionic redox in positive electrode materials in Li-ion batteries provides an additional redox couple besides conventional metal redox, which can be harvested to further boost the energy density of current Li-ion batteries. However, the requirement for the reversible anionic redox activity remains under debate, hindering the rational design of new materials with reversible anionic redox. In this work, we employed differential electrochemical mass spectrometry (DEMS) to monitor the release of oxygen and to quantify the reversibility of the anionic redox of Li[subscript 2]Ru[subscript 0.75]M[subscript 0.25]O[subscript 3](M = Ti, Cr, Mn, Fe, Ru, Sn, Pt, Ir) upon first charge. X-ray absorption spectroscopy, coupled with density functional theory (DFT) calculations, show that various substituents have a minimal effect on the nominal metal redox, yet more ionic substituents and reduced metal–oxygen covalency introduce irreversible oxygen redox, accompanied with easier distortion of the M–O octahedron and a smaller barrier for forming an oxygen dimer within the octahedron. Therefore, a strong metal–oxygen covalency is needed to enhance the reversible oxygen redox. We proposed an electron–phonon-coupled descriptor for the reversibility of oxygen redox, laying the foundation for high-throughput screening of novel materials that enable reversible anionic redox activity.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology. Research Laboratory of Electronics
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DOI of Published Version
https://doi.org/10.1039/d0ee03765f
