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Title: Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ~3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. In this study, we performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery model during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization ofmore » the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. Also, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode.« less
Authors:
 [1] ;  [1] ; ORCiD logo [2]
  1. Texas A & M Univ., College Station, TX (United States). Department of Chemical Engineering
  2. Texas A & M Univ., College Station, TX (United States). Department of Chemical Engineering, Department of Electrical and Computer Engineering and Department of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
EE0007766; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Journal of Molecular Modeling
Additional Journal Information:
Journal Volume: 23; Journal Issue: 4; Journal ID: ISSN 1610-2940
Publisher:
Springer-Verlag
Research Org:
Texas A&M Engineering Experiment Station, College Station, TX (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 36 MATERIALS SCIENCE; Battery; Li-ion; Molecular dynamics; Nanobattery; Silicon anode
OSTI Identifier:
1430651

Galvez-Aranda, Diego E., Ponce, Victor, and Seminario, Jorge M.. Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery. United States: N. p., Web. doi:10.1007/s00894-017-3283-2.
Galvez-Aranda, Diego E., Ponce, Victor, & Seminario, Jorge M.. Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery. United States. doi:10.1007/s00894-017-3283-2.
Galvez-Aranda, Diego E., Ponce, Victor, and Seminario, Jorge M.. 2017. "Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery". United States. doi:10.1007/s00894-017-3283-2. https://www.osti.gov/servlets/purl/1430651.
@article{osti_1430651,
title = {Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery},
author = {Galvez-Aranda, Diego E. and Ponce, Victor and Seminario, Jorge M.},
abstractNote = {Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ~3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. In this study, we performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery model during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li14Si5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. Also, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode.},
doi = {10.1007/s00894-017-3283-2},
journal = {Journal of Molecular Modeling},
number = 4,
volume = 23,
place = {United States},
year = {2017},
month = {3}
}

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