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Kwak, Sang Kyu
Kyu’s MolSim Lab @ UNIST
Research Interests
  • Molecular modeling and simulation, statistical thermodynamics, molecular physics

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Understanding lithium, sodium, and potassium storage mechanisms in silicon oxycarbide

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Title
Understanding lithium, sodium, and potassium storage mechanisms in silicon oxycarbide
Author
Chandra, ChristianDevina, WindaCahyadi, Handi SetiadiKwak, Sang KyuKim, Jaehoon
Issue Date
2022-01
Publisher
Elsevier BV
Citation
CHEMICAL ENGINEERING JOURNAL, v.428, pp.131072
Abstract
The use of silicon oxycarbides (SiOCs) as anode materials in lithium-ion batteries and sodium-ion batteries has risen considerably in recent years. However, the amorphous and complex structures of SiOCs that contains C-rich and O-rich SiOC phases make it difficult to clarify Li+- and Na+-ion storage mechanisms experimentally. This study uncovers the Li+-, Na+-, and K+-ion storage mechanisms in both the O-rich SiO1.5C0.5 and C-rich SiO0.5C1.5 structures using the density functional theory. The ions inserted at the initial discharge process fill the microvoids in the SiOCs. A further ion insertion causes Si–O and Si–C bond cleavage, and thus results in the formation of a large-size free volume, which is favorable for subsequent ion insertion. The reasons for the high Li+-ion storage capacity as compared to Na+-ion are less severe volume expansion, more favorable formation of Li-rich Si compounds and Li–Si alloys. The theoretical K+-ion storage capacities in the O-rich SiO1.5C0.5 and C-rich SiO0.5C1.5 phases are much lower (335 and 186 mAh g−1, respectively) than those of Li+-ion (519 and 681 mAh g−1, respectively) and Na+-ion storages (335 and 681 mAh g−1, respectively). The huge structural instability caused by the repulsive interaction between the K+ ions results in the low storage capacity.
URI
https://scholarworks.unist.ac.kr/handle/201301/53847
URL
https://www.sciencedirect.com/science/article/pii/S1385894721026541?via%3Dihub
DOI
10.1016/j.cej.2021.131072
ISSN
1385-8947
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