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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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Intrinsic Nanodomains in Triplite LiFeSO4F and Its Implication in Lithium-Ion Diffusion

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Title
Intrinsic Nanodomains in Triplite LiFeSO4F and Its Implication in Lithium-Ion Diffusion
Author
Seo, Dong-HwaPark, Kyu-YoungKim, HaegyeomJung, Sung-KyunPark, Min-SikKang, Kisuk
Issue Date
2018-02
Publisher
WILEY-V C H VERLAG GMBH
Citation
ADVANCED ENERGY MATERIALS, v.8, no.6, pp.1701408
Abstract
Triplite-type LiFeSO4F has attracted considerable attention as a promising cathode for next-generation lithium-ion batteries because of its high redox potential based on earth-abundant Fe2+/3+. However, successful extraction/reinsertion of all the lithium ions in triplite host is challenging even at a low current rate, resulting in a low specific capacity. These experimental findings contrast with previous theoretical works that predicted that the triplite structure would be a fast ionic conductor with low activation barriers for lithium-ion hopping. Origin of this discrepancy is elusive to date. Herein, combined first-principles calculations and high-angle annular dark-field scanning transmission electron microscopy analyses reveal that typical triplite structure is composed of nanodomains consisting of corner-shared FeO4F2 octahedra, whereas their domain boundaries are regions of mixed corner/edge-shared FeO4F2 octahedra. More importantly, these locally disordered domain boundaries significantly reduce the overall lithium diffusivity of the materials. Inspired by these findings, this study redesigns triplite structure with sufficiently small sizes to avoid local bottlenecks arising from the domain boundaries, successfully achieving nearly full lithium extraction/reinsertion with high power and energy density. This work represents the first direct observation of the presence of domain boundaries within a crystalline structure playing a critical role in governing the lithium diffusivity in a battery electrode.
URI
https://scholarworks.unist.ac.kr/handle/201301/30520
URL
https://onlinelibrary.wiley.com/doi/full/10.1002/aenm.201701408
DOI
10.1002/aenm.201701408
ISSN
1614-6832
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