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Does capillary evaporation limit the accessibility of nonaqueous electrolytes to the ultrasmall pores of carbon electrodes?

Liu, Kun and Zhang, Pengfei and Wu, Jianzhong (2018) Does capillary evaporation limit the accessibility of nonaqueous electrolytes to the ultrasmall pores of carbon electrodes? Journal of Chemical Physics, 149 (23). Art. No. 234708. ISSN 0021-9606. doi:10.1063/1.5064360.

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Porous carbons have been widely utilized as electrode materials for capacitive energy storage. Whereas the importance of pore size and geometry on the device performance has been well recognized, little guidance is available for identification of carbon materials with ideal porous structures. In this work, we study the phase behavior of ionic fluids in slit pores using the classical density functional theory. Within the framework of the restricted primitive model for nonaqueous electrolytes, we demonstrate that the accessibility of micropores depends not only on the ionic diameters (or desolvation) but also on their wetting behavior intrinsically related to the vapor-liquid or liquid-liquid phase separation of the bulk ionic systems. Narrowing the pore size from several tens of nanometers to subnanometers may lead to a drastic reduction in the capacitance due to capillary evaporation. The wettability of micropores deteriorates as the pore size is reduced but can be noticeably improved by raising the surface electrical potential. The theoretical results provide fresh insights into the properties of confined ionic systems beyond electric double layer models commonly employed for rational design/selection of electrolytes and electrode materials.

Item Type:Article
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URLURL TypeDescription
Liu, Kun0000-0003-1359-7865
Zhang, Pengfei0000-0002-4226-1394
Wu, Jianzhong0000-0002-4582-5941
Additional Information:© 2018 AIP Publishing. (Received 3 October 2018; accepted 26 November 2018; published online 21 December 2018) This work was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Some calculations in this work are performed on the National Energy Research Scientific Computing (NERSC) Center. The authors would like to thank Dr. Jian Jiang for helpful discussions.
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
Issue or Number:23
Record Number:CaltechAUTHORS:20181221-103345255
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91951
Deposited By: George Porter
Deposited On:21 Dec 2018 18:42
Last Modified:16 Nov 2021 03:45

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