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Seo, Dong-Hwa
Computational Energy Materials Science Lab
Research Interests
  • 본 연구실에서는 제일원리 (first-principles) 전산모사 기법을 통해 이차전지용 전극 소재와 고체 전해질 소재에 대해 원자 단위에서 깊이 있게 이해하고 이를 바탕으로 신규 소재를 개발하고 기존 소재의 성능 향상시키는 연구를 진행하고 있습니다. 또한 인공지능 (artificial intelligence)과 기계학습 (Machine learning), 로봇공학 (robotics)을 조합하여 자동 합성/분석을 통한 재료 개발에 대한 연구를 진행하고 있습니다.

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Metal-oxygen decoordination stabilizes anion redox in Li-rich oxides

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Title
Metal-oxygen decoordination stabilizes anion redox in Li-rich oxides
Author
Hong, JihyunGent, William E.Xiao, PenghaoLim, KipilSeo, Dong-HwaWu, JinpengCsernica, Peter M.Takacs, Christopher J.Nordlund, DennisSun, Cheng-JunStone, Kevin H.Passarello, DonataYang, WanliPrendergast, DavidCeder, GerbrandToney, Michael F.Chueh, William C.
Issue Date
2019-03
Publisher
NATURE PUBLISHING GROUP
Citation
NATURE MATERIALS, v.18, no.3, pp.256 - 265
Abstract
Reversible high-voltage redox chemistry is an essential component of many electrochemical technologies, from (electro) catalysts to lithium-ion batteries. Oxygen-anion redox has garnered intense interest for such applications, particularly lithium-ion batteries, as it offers substantial redox capacity at more than 4 V versus Li/Li+ in a variety of oxide materials. However, oxidation of oxygen is almost universally correlated with irreversible local structural transformations, voltage hysteresis and voltage fade, which currently preclude its widespread use. By comprehensively studying the Li2-xIr1-ySnyO3 model system, which exhibits tunable oxidation state and structural evolution with y upon cycling, we reveal that this structure-redox coupling arises from the local stabilization of short approximately 1.8 angstrom metal-oxygen pi bonds and approximately 1.4 angstrom O-O dimers during oxygen redox, which occurs in Li2-xIr1-ySnyO3 through ligand-to-metal charge transfer. Crucially, formation of these oxidized oxygen species necessitates the decoordination of oxygen to a single covalent bonding partner through formation of vacancies at neighbouring cation sites, driving cation disorder. These insights establish a point-defect explanation for why anion redox often occurs alongside local structural disordering and voltage hysteresis during cycling. Our findings offer an explanation for the unique electrochemical properties of lithium-rich layered oxides, with implications generally for the design of materials employing oxygen redox chemistry.
URI
https://scholarworks.unist.ac.kr/handle/201301/30505
URL
https://www.nature.com/articles/s41563-018-0276-1
DOI
10.1038/s41563-018-0276-1
ISSN
1476-1122
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