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Title: Electronic Origin For The Phase Transition From Amorphous LixSi To Crystalline Li15Si4

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 (STEM), electron energy loss spectroscopy (EELS), 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.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1091442
Report Number(s):
PNNL-SA-96285
47714
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
ACS Nano, 7(7):6303-6309
Additional Journal Information:
Journal Name: ACS Nano, 7(7):6303-6309
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Gu, Meng, Wang, Zhiguo, Connell, Justin G., Perea, Daniel E., Lauhon, Lincoln J., Gao, Fei, and Wang, Chong M. Electronic Origin For The Phase Transition From Amorphous LixSi To Crystalline Li15Si4. United States: N. p., 2013. Web. doi:10.1021/nn402349j.
Gu, Meng, Wang, Zhiguo, Connell, Justin G., Perea, Daniel E., Lauhon, Lincoln J., Gao, Fei, & Wang, Chong M. Electronic Origin For The Phase Transition From Amorphous LixSi To Crystalline Li15Si4. United States. https://doi.org/10.1021/nn402349j
Gu, Meng, Wang, Zhiguo, Connell, Justin G., Perea, Daniel E., Lauhon, Lincoln J., Gao, Fei, and Wang, Chong M. 2013. "Electronic Origin For The Phase Transition From Amorphous LixSi To Crystalline Li15Si4". United States. https://doi.org/10.1021/nn402349j.
@article{osti_1091442,
title = {Electronic Origin For The Phase Transition From Amorphous LixSi To Crystalline Li15Si4},
author = {Gu, Meng and Wang, Zhiguo and Connell, Justin G. and Perea, Daniel E. and Lauhon, Lincoln J. and Gao, Fei and Wang, Chong M.},
abstractNote = {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 (STEM), electron energy loss spectroscopy (EELS), 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.},
doi = {10.1021/nn402349j},
url = {https://www.osti.gov/biblio/1091442}, journal = {ACS Nano, 7(7):6303-6309},
number = ,
volume = ,
place = {United States},
year = {Mon Jun 24 00:00:00 EDT 2013},
month = {Mon Jun 24 00:00:00 EDT 2013}
}