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Title: Cation Molecular Structure Affects Mobility and Transport of Electrolytes in Porous Carbons

Abstract

We examined the electrosorption and ion dynamics of imidazolium-based room temperature ionic liquids (RTILs) having short (3-carbon, C3mim +) and long (12-carbon, C12mim +) cations, that is, 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C3mimTFSI) and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C12mimTFSI), confined in ordered mesoporous carbon (OMC) and analyzed the influence of the cation alkyl chain length on the ion dynamics and the capacitive behavior using electrochemical measurements together with quasi-elastic neutron scattering (QENS) observations and classical density functional theory (cDFT) computations. Electrochemical tests highlighted the significant influence of specific applied potentials on accumulated charge storage densities and on the limits of saturation of larger electrolytes in the pores. Computational analyses corroborated these findings and predicted a 16% increase in the capacitance of the smaller-cation electrolyte under high applied potentials. However, QENS experiments revealed a behavior of decoupling of alkyl chain dynamics from the ring in electrolytes with larger ions. cDFT calculations identified density spikes for C12mim + away from the pore walls to further corroborate this unique behavior. Here, our insights into chain length-dependent dynamics and electrosorption in complex electrolyte-electrode systems deepen fundamental understanding of confined RTIL electrolyte behavior in the porous carbon electrodes.

Authors:
ORCiD logo [1];  [2];  [3];  [4]; ORCiD logo [1];  [1]; ORCiD logo [5]; ORCiD logo [5];  [3];  [2]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
  2. Drexel Univ., Philadelphia, PA (United States). A. J. Drexel Nanotechnology Inst., Dept. of Materials Science and Engineering
  3. Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering
  4. Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab., ISIS Neutron Source Pulsed Neutron and Muon Source
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Science Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1505315
Grant/Contract Number:  
AC05-00OR22725; DGE-1326120
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 166; Journal Issue: 4; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; Energy Storage; Molten Salts; Ionic liquid; Quasi-elastic neutron scattering; Supercapacitors

Citation Formats

Osti, Naresh C., Dyatkin, Boris, Gallegos, Alejandro, Voneshen, David, Keum, Jong K., Littrell, Ken, Zhang, Pengfei, Dai, Sheng, Wu, Jianzhong, Gogotsi, Yury, and Mamontov, Eugene. Cation Molecular Structure Affects Mobility and Transport of Electrolytes in Porous Carbons. United States: N. p., 2019. Web. doi:10.1149/2.0131904jes.
Osti, Naresh C., Dyatkin, Boris, Gallegos, Alejandro, Voneshen, David, Keum, Jong K., Littrell, Ken, Zhang, Pengfei, Dai, Sheng, Wu, Jianzhong, Gogotsi, Yury, & Mamontov, Eugene. Cation Molecular Structure Affects Mobility and Transport of Electrolytes in Porous Carbons. United States. doi:10.1149/2.0131904jes.
Osti, Naresh C., Dyatkin, Boris, Gallegos, Alejandro, Voneshen, David, Keum, Jong K., Littrell, Ken, Zhang, Pengfei, Dai, Sheng, Wu, Jianzhong, Gogotsi, Yury, and Mamontov, Eugene. Wed . "Cation Molecular Structure Affects Mobility and Transport of Electrolytes in Porous Carbons". United States. doi:10.1149/2.0131904jes.
@article{osti_1505315,
title = {Cation Molecular Structure Affects Mobility and Transport of Electrolytes in Porous Carbons},
author = {Osti, Naresh C. and Dyatkin, Boris and Gallegos, Alejandro and Voneshen, David and Keum, Jong K. and Littrell, Ken and Zhang, Pengfei and Dai, Sheng and Wu, Jianzhong and Gogotsi, Yury and Mamontov, Eugene},
abstractNote = {We examined the electrosorption and ion dynamics of imidazolium-based room temperature ionic liquids (RTILs) having short (3-carbon, C3mim+) and long (12-carbon, C12mim+) cations, that is, 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C3mimTFSI) and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C12mimTFSI), confined in ordered mesoporous carbon (OMC) and analyzed the influence of the cation alkyl chain length on the ion dynamics and the capacitive behavior using electrochemical measurements together with quasi-elastic neutron scattering (QENS) observations and classical density functional theory (cDFT) computations. Electrochemical tests highlighted the significant influence of specific applied potentials on accumulated charge storage densities and on the limits of saturation of larger electrolytes in the pores. Computational analyses corroborated these findings and predicted a 16% increase in the capacitance of the smaller-cation electrolyte under high applied potentials. However, QENS experiments revealed a behavior of decoupling of alkyl chain dynamics from the ring in electrolytes with larger ions. cDFT calculations identified density spikes for C12mim+ away from the pore walls to further corroborate this unique behavior. Here, our insights into chain length-dependent dynamics and electrosorption in complex electrolyte-electrode systems deepen fundamental understanding of confined RTIL electrolyte behavior in the porous carbon electrodes.},
doi = {10.1149/2.0131904jes},
journal = {Journal of the Electrochemical Society},
issn = {0013-4651},
number = 4,
volume = 166,
place = {United States},
year = {2019},
month = {2}
}

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