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Title: Ion transport and association study of glyme-based electrolytes with lithium and sodium salts

Abstract

Glyme solvents are a promising avenue of research in novel electrolytes, due to their thermal and chemical stability, large electrochemical window, and tunable properties. This work examines the transport properties of LiPF 6 and NaPF 6 salts in Monoglyme (G1), Diglyme (G2), and Tetraglyme (G4). Self-Diffusion coefficients, and degrees of ion association were found through spectroscopic techniques. Raman and Fourier-Transform Infrared (FTIR) spectroscopy exhibited an absorbance peak at 740 cm -1, corresponding to the a 1g mode; known to signify the presence of solvent-separated and contact ion pairs. The increased intensity of this peak for G1 compared to G4 suggests that the electrolyte exhibits stronger association with decreasing solvent size. Nuclear Magnetic Resonance Diffusometry measurements yield self-diffusion coefficients for 7Li, 23Na, and 19F across all samples to be on the order of 10 -9 m 2s -1 in G1, to 10 -11 m 2s -1 in G4. Comparison of conductivities calculated from the measured diffusivities and the Nernst-Einstein equation with conductivity measurements deduced from Electrochemical Impedance Spectroscopy (EIS) determined the ion association degree; the electrolytes were shown to exhibit stronger ion pairing with increased temperature which is attributed to a decrease in the dielectric constant of the solvents with increasingmore » temperature. Plus, the ion association was shown to decrease with increasing solvent molecular size, consistent with FTIR findings.« less

Authors:
 [1];  [2];  [2];  [1]
  1. Hunter College of the City Univ. of New York, New York, NY (United States)
  2. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Electricity
OSTI Identifier:
1502562
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Electrochimica Acta
Additional Journal Information:
Journal Volume: 304; Journal Issue: C; Journal ID: ISSN 0013-4686
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Glyme; Hexafluorophosphate; NMR; Diffusion; Ion pairing

Citation Formats

Morales, Daniel, Ruther, Rose E., Nanda, Jagjit, and Greenbaum, Steven. Ion transport and association study of glyme-based electrolytes with lithium and sodium salts. United States: N. p., 2019. Web. doi:10.1016/j.electacta.2019.02.110.
Morales, Daniel, Ruther, Rose E., Nanda, Jagjit, & Greenbaum, Steven. Ion transport and association study of glyme-based electrolytes with lithium and sodium salts. United States. doi:10.1016/j.electacta.2019.02.110.
Morales, Daniel, Ruther, Rose E., Nanda, Jagjit, and Greenbaum, Steven. Fri . "Ion transport and association study of glyme-based electrolytes with lithium and sodium salts". United States. doi:10.1016/j.electacta.2019.02.110.
@article{osti_1502562,
title = {Ion transport and association study of glyme-based electrolytes with lithium and sodium salts},
author = {Morales, Daniel and Ruther, Rose E. and Nanda, Jagjit and Greenbaum, Steven},
abstractNote = {Glyme solvents are a promising avenue of research in novel electrolytes, due to their thermal and chemical stability, large electrochemical window, and tunable properties. This work examines the transport properties of LiPF6 and NaPF6 salts in Monoglyme (G1), Diglyme (G2), and Tetraglyme (G4). Self-Diffusion coefficients, and degrees of ion association were found through spectroscopic techniques. Raman and Fourier-Transform Infrared (FTIR) spectroscopy exhibited an absorbance peak at 740 cm-1, corresponding to the a1g mode; known to signify the presence of solvent-separated and contact ion pairs. The increased intensity of this peak for G1 compared to G4 suggests that the electrolyte exhibits stronger association with decreasing solvent size. Nuclear Magnetic Resonance Diffusometry measurements yield self-diffusion coefficients for 7Li, 23Na, and 19F across all samples to be on the order of 10-9 m2s-1 in G1, to 10-11 m2s-1 in G4. Comparison of conductivities calculated from the measured diffusivities and the Nernst-Einstein equation with conductivity measurements deduced from Electrochemical Impedance Spectroscopy (EIS) determined the ion association degree; the electrolytes were shown to exhibit stronger ion pairing with increased temperature which is attributed to a decrease in the dielectric constant of the solvents with increasing temperature. Plus, the ion association was shown to decrease with increasing solvent molecular size, consistent with FTIR findings.},
doi = {10.1016/j.electacta.2019.02.110},
journal = {Electrochimica Acta},
number = C,
volume = 304,
place = {United States},
year = {2019},
month = {3}
}

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This content will become publicly available on March 1, 2020
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