First-Principles Study of Lithiation of Type i Ba-Doped Silicon Clathrates

Xihong Peng, Qun Wei, Ying Li, Candace Chan

Research output: Contribution to journalArticle

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Abstract

Silicon clathrate materials, previously known for their superconducting and thermoelectric characteristics, have also recently been investigated for their electrochemical properties as anodes for lithium-ion batteries due to their unique cage structure and ability to incorporate extrinsic guest atoms. To better understand the preferred structures for small degrees of lithiation, first-principles density functional theory (DFT) was used to investigate the type I clathrate compounds Si46, LixBaySi46 (0 ≤ x ≤ 8; y = 6, 8), and LixBayAl6Si40 (0 ≤ x ≤ 8; y = 6). The formation energies, electronic band structures, and density of states (DOS) were calculated. Lithium occupation in framework vacancies, empty and Ba-occupied cage cavities, and near the pentagonal and hexagonal faces of the clathrate polyhedra was considered. The data showed that Li insertion into framework or Ba vacancies could stabilize the clathrate structure. Silicon substitution by Al lowered the formation energies of the lithiated compounds and mitigated the calculated volume increase upon lithiation. The results also showed that it is energetically feasible for multiple guest atoms to be placed in the Si24 cages. Changes in the clathrate atomic structure (e.g., bond lengths and angles) and electronic structure were highly dependent on the location of the Li and guest atom spacing within the clathrate framework. The results from this study can elucidate the preferred structural configurations for Li in type I, Ba-doped silicon clathrates and also be informative for efforts related to understanding the structures obtained after electrochemical insertion of lithium into silicon clathrates.

Original languageEnglish
Pages (from-to)28247-28257
Number of pages11
JournalJournal of Physical Chemistry C
Volume119
Issue number51
DOIs
Publication statusPublished - Dec 24 2015

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clathrates
Silicon
silicon
Lithium
Atoms
Vacancies
lithium
Bond length
energy of formation
Electrochemical properties
Band structure
Electronic structure
Density functional theory
insertion
Anodes
Substitution reactions
atoms
polyhedrons
atomic structure
occupation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

First-Principles Study of Lithiation of Type i Ba-Doped Silicon Clathrates. / Peng, Xihong; Wei, Qun; Li, Ying; Chan, Candace.

In: Journal of Physical Chemistry C, Vol. 119, No. 51, 24.12.2015, p. 28247-28257.

Research output: Contribution to journalArticle

Peng, Xihong ; Wei, Qun ; Li, Ying ; Chan, Candace. / First-Principles Study of Lithiation of Type i Ba-Doped Silicon Clathrates. In: Journal of Physical Chemistry C. 2015 ; Vol. 119, No. 51. pp. 28247-28257.
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