Atomistic Observation on Lithiation and Delithiation Behaviors of Silicon Nanowires: Reactive Molecular Dynamics Simulation

Title
Atomistic Observation on Lithiation and Delithiation Behaviors of Silicon Nanowires: Reactive Molecular Dynamics Simulation
Authors
정현주재용이광렬한상수
Keywords
Silicon nanowire; lithiation; Reactive force field; Molecular dynamics simulation
Issue Date
2014-06
Publisher
17th International Meeting on Lithium Batteries
Abstract
Recently silicon has attracted intense interest as a promising anode material of lithium-ion batteries due to its extremely high capacity of 4200 mA/g (for Li4.2Si) that is much higher than 372 mAh/g (for LiC6) of graphite. However, it seriously suffers from large volume change (even up to 300%) of the electrode upon lithiation, leading to its pulverization or mechanical failure during lithiation / de-lithiation processes and the rapid capacity fading. To overcome this problem, Si nanowires have been considered. Use of such Si nanowires provides their facile relaxation during lithiation / de-lithiation without mechanical breaking. To design better Si electrodes, a study to unveil atomic-scale mechanisms involving the volume expansion and the phase transformation upon lithiation is critical. In order to investigate the lithiation mechanism in Si nanowires, we have developed a reactive force field (ReaxFF) for Li-Si systems based on density functional theory calculations. The ReaxFF method provides a highly transferable simulation method for atomistic scale simulation on chemical reactions at the nanosecond and nanometer scale. Molecular dynamics with the ReaxFF reproduces well experimental anisotropic volume expansion of Si nanowires during lithiation and diffusion behaviors of lithium atoms, indicating that it would be definitely helpful to investigate lithium mechanism of Si electrodes and then design new Si electrodes.
URI
http://pubs.kist.re.kr/handle/201004/48480
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KIST Publication > Conference Paper
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