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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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A New Strategy for High-Voltage Cathodes for K-Ion Batteries: Stoichiometric KVPO4F

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Title
A New Strategy for High-Voltage Cathodes for K-Ion Batteries: Stoichiometric KVPO4F
Author
Kim, HaegyeomSeo, Dong-HwaBianchini, MatteoClement, Raphaele J.Kim, HyunchulKim, Jae ChulTian, YaosenShi, TanYoon, Won-SubCeder, Gerbrand
Issue Date
2018-09
Publisher
WILEY-V C H VERLAG GMBH
Citation
ADVANCED ENERGY MATERIALS, v.8, no.26, pp.1801591
Abstract
The exploration of high-energy-density cathode materials is vital to the practical use of K-ion batteries. Layered K-metal oxides have too high a voltage slope due to their large K+-K+ interaction, resulting in low specific capacity and average voltage. In contrast, the 3D arrangement of K+, with polyanions separating them, reduces the strength of the effective K+-K+ repulsion, which in turn increases specific capacity and voltage. Here, stoichiometric KVPO4F for use as a high-energy-density K-ion cathode is developed. The KVPO4F cathode delivers a reversible capacity of approximate to 105 mAh g(-1) with an average voltage of approximate to 4.3 V (vs K/K+), resulting in a gravimetric energy density of approximate to 450 Wh kg(-1). During electrochemical cycling, the KxVPO4F cathode goes through various intermediate phases at x = 0.75, 0.625, and 0.5 upon K extraction and reinsertion, as determined by ex situ X-ray diffraction characterization and ab initio calculations. This work further explains the role of oxygen substitution in KVPO4+xF1-x: the oxygenation of KVPO4F leads to an anion-disordered structure which prevents the formation of K+/vacancy orderings without electrochemical plateaus and hence to a smoother voltage profile.
URI
https://scholarworks.unist.ac.kr/handle/201301/30518
URL
https://onlinelibrary.wiley.com/doi/full/10.1002/aenm.201801591
DOI
10.1002/aenm.201801591
ISSN
1614-6832
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