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Title: Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation

Abstract

The molecular-scale dynamic properties of the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or [C4mim+ ][Tf2N ], confined in hierarchical microporous mesoporous carbon, were investigated using neutron spin echo (NSE) and molecular dynamics (MD) simulations. Both NSE and MD reveal pronounced slowing of the overall collective dynamics, including the presence of an immobilized fraction of RTIL at the pore wall, on the time scales of these approaches. A fraction of the dynamics, corresponding to RTIL inside 0.75 nm micropores located along the mesopore surfaces, are faster than those of RTIL in direct contact with the walls of 5.8 nm and 7.8 nm cylindrical mesopores. This behavior is ascribed to the near-surface confined-ion density fluctuations resulting from the ion ion and ion wall interactions between the micropores and mesopores as well as their confinement geometries. Strong micropore RTIL interactions result in less-coordinated RTIL within the micropores than in the bulk fluid. Increasing temperature from 296 K to 353 K reduces the immobilized RTIL fraction and results in nearly an order of magnitude increase in the RTIL dynamics. The observed interfacial phenomena underscore the importance of tailoring the surface properties of porous carbons to achieve desirable electrolyte dynamic behavior, since this impactsmore » the performance in applications such as electrical energy storage devices.« less

Authors:
 [1];  [1];  [1];  [2];  [1];  [1];  [3];  [1];  [1];  [1]
  1. ORNL
  2. Vanderbilt University, Nashville
  3. National Institute of Standards and Technology (NIST)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1149778
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Carbon
Additional Journal Information:
Journal Volume: 78; Journal ID: ISSN 0008-6223
Country of Publication:
United States
Language:
English

Citation Formats

Banuelos, Jose Leo, Feng, Guang, Fulvio, Pasquale F, Li, Song, Rother, Gernot, Arend, Nikolas, Faraone, Antonio, Dai, Sheng, Cummings, Peter T, and Wesolowski, David J. Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation. United States: N. p., 2014. Web. doi:10.1016/j.carbon.2014.07.020.
Banuelos, Jose Leo, Feng, Guang, Fulvio, Pasquale F, Li, Song, Rother, Gernot, Arend, Nikolas, Faraone, Antonio, Dai, Sheng, Cummings, Peter T, & Wesolowski, David J. Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation. United States. doi:10.1016/j.carbon.2014.07.020.
Banuelos, Jose Leo, Feng, Guang, Fulvio, Pasquale F, Li, Song, Rother, Gernot, Arend, Nikolas, Faraone, Antonio, Dai, Sheng, Cummings, Peter T, and Wesolowski, David J. Wed . "Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation". United States. doi:10.1016/j.carbon.2014.07.020.
@article{osti_1149778,
title = {Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation},
author = {Banuelos, Jose Leo and Feng, Guang and Fulvio, Pasquale F and Li, Song and Rother, Gernot and Arend, Nikolas and Faraone, Antonio and Dai, Sheng and Cummings, Peter T and Wesolowski, David J},
abstractNote = {The molecular-scale dynamic properties of the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or [C4mim+ ][Tf2N ], confined in hierarchical microporous mesoporous carbon, were investigated using neutron spin echo (NSE) and molecular dynamics (MD) simulations. Both NSE and MD reveal pronounced slowing of the overall collective dynamics, including the presence of an immobilized fraction of RTIL at the pore wall, on the time scales of these approaches. A fraction of the dynamics, corresponding to RTIL inside 0.75 nm micropores located along the mesopore surfaces, are faster than those of RTIL in direct contact with the walls of 5.8 nm and 7.8 nm cylindrical mesopores. This behavior is ascribed to the near-surface confined-ion density fluctuations resulting from the ion ion and ion wall interactions between the micropores and mesopores as well as their confinement geometries. Strong micropore RTIL interactions result in less-coordinated RTIL within the micropores than in the bulk fluid. Increasing temperature from 296 K to 353 K reduces the immobilized RTIL fraction and results in nearly an order of magnitude increase in the RTIL dynamics. The observed interfacial phenomena underscore the importance of tailoring the surface properties of porous carbons to achieve desirable electrolyte dynamic behavior, since this impacts the performance in applications such as electrical energy storage devices.},
doi = {10.1016/j.carbon.2014.07.020},
journal = {Carbon},
issn = {0008-6223},
number = ,
volume = 78,
place = {United States},
year = {2014},
month = {1}
}