Electronic origin for the phase transition from amorphous LixSi to crystalline Li15Si4

Meng Gu, Zhiguo Wang, Justin G. Connell, Daniel E. Perea, Lincoln James Lauhon, Fei Gao, Chongmin Wang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

102 Scopus citations

Abstract

Silicon has been widely explored as an anode material for lithium ion battery. Upon lithiation, silicon transforms to amorphous LixSi (a-LixSi) via electrochemical-driven solid-state amorphization. With increasing lithium concentration, a-LixSi transforms to crystalline Li15Si4 (c-Li15Si4). The mechanism of this crystallization process is not known. In this paper, we report the fundamental characteristics of the phase transition of a-LixSi to c-Li15Si4 using in situ scanning transmission electron microscopy, electron energy loss spectroscopy, and density function theory (DFT) calculation. We find that when the lithium concentration in a-LixSi reaches a critical value of x = 3.75, the a-Li3.75Si spontaneously and congruently transforms to c-Li15Si4 by a process that is solely controlled by the lithium concentration in the a-LixSi, involving neither large-scale atomic migration nor phase separation. DFT calculations indicate that c-Li15Si4 formation is favored over other possible crystalline phases due to the similarity in electronic structure with a-Li3.75Si.

Original languageEnglish (US)
Pages (from-to)6303-6309
Number of pages7
JournalACS nano
Volume7
Issue number7
DOIs
StatePublished - Jul 23 2013

Keywords

  • EELS
  • Si
  • electronic structure
  • in situ TEM
  • lithiation
  • phase transition

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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