Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect

Type
Article

Authors
Zhang, Qianfan
Cui, Yi
Wang, Enge

KAUST Grant Number
KUS-l1-001-12

Online Publication Date
2011-04-22

Print Publication Date
2011-05-19

Date
2011-04-22

Abstract
Silicon nanowires (SiNWs) have recently been shown to be promising as high capacity lithium battery anodes. SiNWs can be grown with their long axis along several different crystallographic directions. Due to distinct atomic configuration and electronic structure of SiNWs with different axial orientations, their lithium insertion behavior could be different. This paper focuses on the characteristics of single Li defects, including binding energy, diffusion barriers, and dependence on uniaxial strain in [110], [100], [111], and [112] SiNWs. Our systematic ab initio study suggests that the Si-Li interaction is weaker when the Si-Li bond direction is aligned close to the SiNW long axis. This results in the [110] and [111] SiNWs having the highest and lowest Li binding energy, respectively, and it makes the diffusion barrier along the SiNW axis lower than other pathways. Under external strain, it was found that [110] and [001] SiNWs are the most and least sensitive, respectively. For diffusion along the axial direction, the barrier increases (decreases) under tension (compression). This feature results in a considerable difference in the magnitude of the energy barrier along different diffusion pathways. © 2011 American Chemical Society.

Citation
Zhang Q, Cui Y, Wang E (2011) Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect. The Journal of Physical Chemistry C 115: 9376–9381. Available: http://dx.doi.org/10.1021/jp1115977.

Acknowledgements
This work was supported by CAS and NSFC. E.W. acknowledges Stanford’s GCEP visiting scholar program. We also gratefully acknowledge the computational time provided by the Swedish agency SNAC. Y.C. acknowledges support from the King Abdullah University of Science and Technology (KAUST) Investigator Award (No. KUS-l1-001-12), Stanford GCEP, and US ONR.

Publisher
American Chemical Society (ACS)

Journal
The Journal of Physical Chemistry C

DOI
10.1021/jp1115977

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