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Title: Ionic liquid structure, dynamics, and electrosorption in carbon electrodes with bimodal pores and heterogeneous surfaces

Abstract

In this paper, we investigate the aggregation, diffusion, and resulting electrochemical behavior of ionic liquids inside carbon electrodes with complex pore architectures and surface chemistries. Carbide-derived carbons (CDCs) with bimodal porosities and defunctionalized or oxidized electrode surfaces served as model electrode materials. Our goal was to obtain a fundamental understanding of room-temperature ionic liquid ion orientation, mobility, and electrosorption behavior. Neat 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide confined in CDCs was studied using an integrated experimental and modeling approach, consisting of quasielastic neutron scattering, small-angle neutron scattering, X-ray pair distribution function analysis, and electrochemical measurements, which were combined with molecular dynamics simulations. Our analysis shows that surface oxygen groups increase the diffusion of confined electrolytes. Consequently, the ions become more than twice as mobile in oxygen-rich pores. Although greater self-diffusion of ions translates into higher electrochemical mobilities in oxidized pores, bulk-like behavior of ions dominates in the larger mesopores and increases the overall capacitance in defunctionalized pores. Experimental results highlight strong confinement and surface effects of carbon electrodes on electrolyte behavior, and molecular dynamics simulations yield insight into diffusion and capacitance differences in specific pore regions. Finally, we demonstrate the significance of surface defects on electrosorption dynamics of complex electrolytes in hierarchical pore architecturesmore » of supercapacitor electrodes.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [2];  [2];  [4];  [4];  [3];  [4]; ORCiD logo [1]
  1. Drexel Univ., Philadelphia, PA (United States). A.J. Drexel Nanomaterials Inst. Dept. of Materials Science and Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
  3. Vanderbilt Univ., Nashville, TN (United States). Chemical and Biomolecular Engineering
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Drexel Univ., Philadelphia, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1432166
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Carbon
Additional Journal Information:
Journal Volume: 129; Journal ID: ISSN 0008-6223
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; energy storage; carbide-derived carbon; ionic liquid; neutron scattering; self-diffusion; supercapacitor; pair distribution function; surface chemistry; molecular dynamics; interface

Citation Formats

Dyatkin, Boris, Osti, Naresh C., Zhang, Yu, Wang, Hsiu-Wen, Mamontov, Eugene, Heller, William T., Zhang, Pengfei, Rother, Gernot, Cummings, Peter T., Wesolowski, David J., and Gogotsi, Yury. Ionic liquid structure, dynamics, and electrosorption in carbon electrodes with bimodal pores and heterogeneous surfaces. United States: N. p., 2017. Web. doi:10.1016/j.carbon.2017.12.001.
Dyatkin, Boris, Osti, Naresh C., Zhang, Yu, Wang, Hsiu-Wen, Mamontov, Eugene, Heller, William T., Zhang, Pengfei, Rother, Gernot, Cummings, Peter T., Wesolowski, David J., & Gogotsi, Yury. Ionic liquid structure, dynamics, and electrosorption in carbon electrodes with bimodal pores and heterogeneous surfaces. United States. doi:10.1016/j.carbon.2017.12.001.
Dyatkin, Boris, Osti, Naresh C., Zhang, Yu, Wang, Hsiu-Wen, Mamontov, Eugene, Heller, William T., Zhang, Pengfei, Rother, Gernot, Cummings, Peter T., Wesolowski, David J., and Gogotsi, Yury. Tue . "Ionic liquid structure, dynamics, and electrosorption in carbon electrodes with bimodal pores and heterogeneous surfaces". United States. doi:10.1016/j.carbon.2017.12.001.
@article{osti_1432166,
title = {Ionic liquid structure, dynamics, and electrosorption in carbon electrodes with bimodal pores and heterogeneous surfaces},
author = {Dyatkin, Boris and Osti, Naresh C. and Zhang, Yu and Wang, Hsiu-Wen and Mamontov, Eugene and Heller, William T. and Zhang, Pengfei and Rother, Gernot and Cummings, Peter T. and Wesolowski, David J. and Gogotsi, Yury},
abstractNote = {In this paper, we investigate the aggregation, diffusion, and resulting electrochemical behavior of ionic liquids inside carbon electrodes with complex pore architectures and surface chemistries. Carbide-derived carbons (CDCs) with bimodal porosities and defunctionalized or oxidized electrode surfaces served as model electrode materials. Our goal was to obtain a fundamental understanding of room-temperature ionic liquid ion orientation, mobility, and electrosorption behavior. Neat 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide confined in CDCs was studied using an integrated experimental and modeling approach, consisting of quasielastic neutron scattering, small-angle neutron scattering, X-ray pair distribution function analysis, and electrochemical measurements, which were combined with molecular dynamics simulations. Our analysis shows that surface oxygen groups increase the diffusion of confined electrolytes. Consequently, the ions become more than twice as mobile in oxygen-rich pores. Although greater self-diffusion of ions translates into higher electrochemical mobilities in oxidized pores, bulk-like behavior of ions dominates in the larger mesopores and increases the overall capacitance in defunctionalized pores. Experimental results highlight strong confinement and surface effects of carbon electrodes on electrolyte behavior, and molecular dynamics simulations yield insight into diffusion and capacitance differences in specific pore regions. Finally, we demonstrate the significance of surface defects on electrosorption dynamics of complex electrolytes in hierarchical pore architectures of supercapacitor electrodes.},
doi = {10.1016/j.carbon.2017.12.001},
journal = {Carbon},
number = ,
volume = 129,
place = {United States},
year = {Tue Dec 05 00:00:00 EST 2017},
month = {Tue Dec 05 00:00:00 EST 2017}
}

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