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Title: Carbons with Regular Pore Geometry Yield Fundamental Insights into Supercapacitor Charge Storage

Abstract

We conduct molecular dynamics simulations of electrical double-layer capacitors (EDLCs) using a library of ordered, porous carbon electrode materials called zeolite templated carbons (ZTCs). The well-defined pore shapes of the ZTCs enable us to determine the influence of pore geometry on both charging dynamics and charge storage mechanisms in EDLCs, also referred to as supercapacitors. We show that charging dynamics are negatively correlated with the pore-limiting diameter of the electrode material and display signatures of both progressive charging and ion trapping. However, the equilibrium capacitance, unlike charging dynamics, is not strongly correlated to commonly used, purely geometric descriptors such as pore size. Instead, we find a strong correlation of capacitance to the charge compensation per carbon (CCpC), a descriptor we define in this work as the average charge of the electrode atoms within the coordination shell of a counterion. A high CCpC indicates efficient charge storage, as the strong partial charges of the electrode are able to screen counterion charge, enabling higher ion loading and thus more charge storage within the electrode at a fixed applied voltage. We determine that adsorption sites with a high CCpC tend to be found within pockets with a smaller radius of curvature, where themore » counterions are able to minimize their distance with multiple points on the electrode surface, and therefore induce stronger local partial charges.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of California, Berkeley, CA (United States); École polytechnique fédérale de Lausanne (EPFL), Sion (Switzerland)
  2. Univ. de Toulouse (France); Federation de Recherche CNRS, Amiens (France)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; European Research Council (ERC)
OSTI Identifier:
1591831
Grant/Contract Number:  
AC02-05CH11231; 714581
Resource Type:
Accepted Manuscript
Journal Name:
ACS Central Science
Additional Journal Information:
Journal Volume: 5; Journal Issue: 11; Journal ID: ISSN 2374-7943
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; electrical properties; electrodes; ions; mathematical methods materials

Citation Formats

Liu, Yifei Michelle, Merlet, Céline, and Smit, Berend. Carbons with Regular Pore Geometry Yield Fundamental Insights into Supercapacitor Charge Storage. United States: N. p., 2019. Web. https://doi.org/10.1021/acscentsci.9b00800.
Liu, Yifei Michelle, Merlet, Céline, & Smit, Berend. Carbons with Regular Pore Geometry Yield Fundamental Insights into Supercapacitor Charge Storage. United States. https://doi.org/10.1021/acscentsci.9b00800
Liu, Yifei Michelle, Merlet, Céline, and Smit, Berend. Fri . "Carbons with Regular Pore Geometry Yield Fundamental Insights into Supercapacitor Charge Storage". United States. https://doi.org/10.1021/acscentsci.9b00800. https://www.osti.gov/servlets/purl/1591831.
@article{osti_1591831,
title = {Carbons with Regular Pore Geometry Yield Fundamental Insights into Supercapacitor Charge Storage},
author = {Liu, Yifei Michelle and Merlet, Céline and Smit, Berend},
abstractNote = {We conduct molecular dynamics simulations of electrical double-layer capacitors (EDLCs) using a library of ordered, porous carbon electrode materials called zeolite templated carbons (ZTCs). The well-defined pore shapes of the ZTCs enable us to determine the influence of pore geometry on both charging dynamics and charge storage mechanisms in EDLCs, also referred to as supercapacitors. We show that charging dynamics are negatively correlated with the pore-limiting diameter of the electrode material and display signatures of both progressive charging and ion trapping. However, the equilibrium capacitance, unlike charging dynamics, is not strongly correlated to commonly used, purely geometric descriptors such as pore size. Instead, we find a strong correlation of capacitance to the charge compensation per carbon (CCpC), a descriptor we define in this work as the average charge of the electrode atoms within the coordination shell of a counterion. A high CCpC indicates efficient charge storage, as the strong partial charges of the electrode are able to screen counterion charge, enabling higher ion loading and thus more charge storage within the electrode at a fixed applied voltage. We determine that adsorption sites with a high CCpC tend to be found within pockets with a smaller radius of curvature, where the counterions are able to minimize their distance with multiple points on the electrode surface, and therefore induce stronger local partial charges.},
doi = {10.1021/acscentsci.9b00800},
journal = {ACS Central Science},
number = 11,
volume = 5,
place = {United States},
year = {2019},
month = {11}
}

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Cited by: 8 works
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