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Title: Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces

The use of high concentration salts in electrolyte solutions of lithium-sulfur (Li-S) batteries has been shown beneficial for mitigating some effects such as polysulfide shuttle and dendrite growth at the Li metal anode. Such complex solutions have structural, dynamical, and reactivity associated issues that need to be analyzed for a better understanding of the reasons behind such beneficial effects. A passivation interfacial layer known as solid-electrolyte interphase (SEI) is generated during battery cycling as a result of electron transfer from the metal anode causing electrolyte decomposition. Here in this work, we investigate using density functional theory and ab initio molecular dynamics simulations the salt decomposition, solvation effects, interactions among intermediate products and other species, and potential components of the SEI layer as a function of chemical nature and concentration of the salt, for lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) at 1M and 4M concentrations in dimethoxyethane. It is found that LiTFSI undergoes a less complete reduction and facilitates charge transfer from the anode, whereas LiFSI shows a more complete decomposition forming LiF as one of the main SEI products. In addition, the specific decomposition mechanisms of each salt clearly point to the initial SEI components and the potential mainmore » products derived from them. Finally, very complex networks are found among the salt and solvent molecules in their attempt to maximize Li ion solvation that is quantified through the determination of coordination numbers.« less
Authors:
 [1] ;  [2] ; ORCiD logo [3]
  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 and Department of Materials Science and Engineering
  3. Texas A & M Univ., College Station, TX (United States). Department of Chemical Engineering, Department of Materials Science and Engineering and Department of Chemistry
Publication Date:
Grant/Contract Number:
EE0006832
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 1; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
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; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1430634

Camacho-Forero, Luis E., Smith, Taylor W., and Balbuena, Perla B.. Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces. United States: N. p., Web. doi:10.1021/acs.jpcc.6b10774.
Camacho-Forero, Luis E., Smith, Taylor W., & Balbuena, Perla B.. Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces. United States. doi:10.1021/acs.jpcc.6b10774.
Camacho-Forero, Luis E., Smith, Taylor W., and Balbuena, Perla B.. 2016. "Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces". United States. doi:10.1021/acs.jpcc.6b10774. https://www.osti.gov/servlets/purl/1430634.
@article{osti_1430634,
title = {Effects of High and Low Salt Concentration in Electrolytes at Lithium–Metal Anode Surfaces},
author = {Camacho-Forero, Luis E. and Smith, Taylor W. and Balbuena, Perla B.},
abstractNote = {The use of high concentration salts in electrolyte solutions of lithium-sulfur (Li-S) batteries has been shown beneficial for mitigating some effects such as polysulfide shuttle and dendrite growth at the Li metal anode. Such complex solutions have structural, dynamical, and reactivity associated issues that need to be analyzed for a better understanding of the reasons behind such beneficial effects. A passivation interfacial layer known as solid-electrolyte interphase (SEI) is generated during battery cycling as a result of electron transfer from the metal anode causing electrolyte decomposition. Here in this work, we investigate using density functional theory and ab initio molecular dynamics simulations the salt decomposition, solvation effects, interactions among intermediate products and other species, and potential components of the SEI layer as a function of chemical nature and concentration of the salt, for lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) at 1M and 4M concentrations in dimethoxyethane. It is found that LiTFSI undergoes a less complete reduction and facilitates charge transfer from the anode, whereas LiFSI shows a more complete decomposition forming LiF as one of the main SEI products. In addition, the specific decomposition mechanisms of each salt clearly point to the initial SEI components and the potential main products derived from them. Finally, very complex networks are found among the salt and solvent molecules in their attempt to maximize Li ion solvation that is quantified through the determination of coordination numbers.},
doi = {10.1021/acs.jpcc.6b10774},
journal = {Journal of Physical Chemistry. C},
number = 1,
volume = 121,
place = {United States},
year = {2016},
month = {12}
}