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Anisotropic Volume Expansion of Crystalline Silicon during Electrochemical Lithium Insertion: An Atomic Level Rationale

Cited 85 time in Web of Science Cited 85 time in Scopus
Authors
Jung, Sung Chul; Choi, Jang Wook; Han, Young-Kyu
Issue Date
2012-10
Citation
Nano Letters, Vol.12 No.10, pp.5342-5347
Keywords
Lithium-ion batterysilicon anodeanisotropic volume expansiondensity functional calculationinterfacial energymolecular dynamics
Abstract
The volume expansion of silicon is the most important feature for electrochemical operations of high capacity Si anodes in lithium ion batteries. Recently, the unexpected anisotropic volume expansion of Si during lithiation has been experimentally observed, but its atomic-level origin is still unclear. By employing first-principles molecular dynamics simulations, herein, we report that the interfacial energy at the phase boundary of amorphous LixSi/crystalline Si plays a very critical role in lithium diffusion and thus volume expansion. While the interface formation turns out to be favorable at x = 3.4 for all of the (100), (110), and (111) orientations, the interfacial energy for the (110) interface is the smallest, which is indeed linked to the preferential volume expansion along the (110) direction because the preferred (110) interface would promote lithiation behind the interface. Utilizing the structural characteristic of the Si(110) surface, local Li density at the (110) interface is especially high reaching Li5.5Si. Our atomic-level calculations enlighten the importance of the interfacial energy in the volume expansion of Si and offer an explanation for the previously unsolved perspective.
ISSN
1530-6984
URI
http://hdl.handle.net/10371/164559
DOI
https://doi.org/10.1021/nl3027197
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Journal Papers (저널논문_화학생물공학부)
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