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Title: Communication: Spectroscopic characterization of a strongly interacting C (2) H group on the EMIM + cation in the (EMIM + ) 2 X (X = BF 4 , Cl, Br, and I) ternary building blocks of ionic liquids

Authors:
 [1];  [1]; ORCiD logo [1]
  1. Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520-8107, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1413549
Grant/Contract Number:
FG02-00ER15800
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 147; Journal Issue: 23; Related Information: CHORUS Timestamp: 2018-02-14 20:21:41; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Gorlova, Olga, Craig, Stephanie M., and Johnson, Mark A. Communication: Spectroscopic characterization of a strongly interacting C (2) H group on the EMIM + cation in the (EMIM + ) 2 X − (X = BF 4 , Cl, Br, and I) ternary building blocks of ionic liquids. United States: N. p., 2017. Web. doi:10.1063/1.5009009.
Gorlova, Olga, Craig, Stephanie M., & Johnson, Mark A. Communication: Spectroscopic characterization of a strongly interacting C (2) H group on the EMIM + cation in the (EMIM + ) 2 X − (X = BF 4 , Cl, Br, and I) ternary building blocks of ionic liquids. United States. doi:10.1063/1.5009009.
Gorlova, Olga, Craig, Stephanie M., and Johnson, Mark A. 2017. "Communication: Spectroscopic characterization of a strongly interacting C (2) H group on the EMIM + cation in the (EMIM + ) 2 X − (X = BF 4 , Cl, Br, and I) ternary building blocks of ionic liquids". United States. doi:10.1063/1.5009009.
@article{osti_1413549,
title = {Communication: Spectroscopic characterization of a strongly interacting C (2) H group on the EMIM + cation in the (EMIM + ) 2 X − (X = BF 4 , Cl, Br, and I) ternary building blocks of ionic liquids},
author = {Gorlova, Olga and Craig, Stephanie M. and Johnson, Mark A.},
abstractNote = {},
doi = {10.1063/1.5009009},
journal = {Journal of Chemical Physics},
number = 23,
volume = 147,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on December 15, 2018
Publisher's Accepted Manuscript

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  • This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li{sup +} coordination and transportation were studied in the ternary electrolyte system, i.e., PEO{sub 16}LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generatedmore » significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.« less
  • Dynamic crossover above T g has been recognized as a characteristic feature of molecular dynamics of liquids approaching glass transition. Experimentally, it is manifested as a change in Vogel–Fulcher–Tammann dependence or a breakdown of the Stokes–Einstein and related relations. In this study, we report the exception from this rather general pattern of behavior. By means of dielectric, ultrasonic, rheological, and calorimetric methods, dynamics of two good ionic conductors (BMIm) 2[Co(NCS) 4] and (EMIm) 2[Co(NCS) 4] of less common stoichiometry (2:1) was studied in a very broad temperature range. However, none of the mentioned dynamic changes was observed in the entiremore » studied temperature range. On the contrary, the single VFT and the same fractional Walden coefficient were found for conductivity and viscosity changes over 12 decades. Finally and moreover, ultrasonic studies revealed that the data at temperatures which cover the normal liquid region cannot be fitted by a single exponential decay, and the Cole–Cole function should be used instead.« less
  • Dynamic crossover above T g has been recognized as a characteristic feature of molecular dynamics of liquids approaching glass transition. Experimentally, it is manifested as a change in Vogel Fulcher Tammann dependence or a breakdown of the Stokes Einstein and related relations. In this paper, we report the exception from this rather general pattern of behavior. By means of dielectric, ultrasonic, rheological, and calorimetric methods, dynamics of two good ionic conductors (BMIm) 2[Co(NCS) 4] and (EMIm) 2[Co(NCS) 4] of less common stoichiometry (2:1) was studied in a very broad temperature range. However, none of the mentioned dynamic changes was observedmore » in the entire studied temperature range. On the contrary, the single VFT and the same fractional Walden coefficient were found for conductivity and viscosity changes over 12 decades. Furthermore, ultrasonic studies revealed that the data at temperatures which cover the normal liquid region cannot be fitted by a single exponential decay, and the Cole Cole function should be used instead.« less
  • We clarify the role of the critical imidazolium C{sub (2)}H position (the central C between N atoms in the heterocycle) in the assembly motif of the [EMIM][BF{sub 4}] ionic liquid by analyzing the vibrational spectra of the bare EMIM{sup +} ion as well as that of the cationic [EMIM]{sub 2}[BF{sub 4}]{sup +} (EMIM{sup +} = 1-ethyl-3-methylimidazolium, C{sub 6}H{sub 11}N{sub 2}{sup +}) cluster. Vibrational spectra of the cold, mass-selected ions are obtained using cryogenic ion vibrational predissociation of weakly bound D{sub 2} molecules formed in a 10 K ion trap. The C{sub (2)}H behavior is isolated by following the evolution ofmore » key vibrational features when the C{sub (2)} hydrogen, the proposed binding location of the anion to the imidazolium ring, is replaced by either deuterium or a methyl group (i.e., in the EMMIM{sup +} analogue). Strong features in the ring CH stretching region of the bare ion are traced to Fermi resonances with overtones of lower frequency modes. Upon incorporation into the EMIM{sup +} ⋅ ⋅ ⋅ BF{sub 4}{sup −} ⋅ ⋅ ⋅ EMIM{sup +} ternary complex, the C{sub (2)}H oscillator strength is dramatically increased, accounting for the much more complicated patterns derived from the EMIM{sup +} ring CH stretches in the light isotopomer, which are strongly suppressed in the deuterated analogue. Further changes in the spectra that occur when the C{sub (2)}H is replaced by a methyl group are consistent with BF{sub 4}{sup −} attachment directly to the imidazolium ring in an arrangement that maximizes the electrostatic interaction between the molecular ions.« less