Capacitance of nanoporous carbon-based supercapacitors is a trade-off between the concentration and the separability of the ions

Burt, Ryan, Breitsprecher, Konrad, Daffos, Barbara, Taberna, Pierre-Louis, Simon, Patrice, Birkett, Greg, Zhao, X. S., Holm, Christian and Salanne, Mathieu (2016) Capacitance of nanoporous carbon-based supercapacitors is a trade-off between the concentration and the separability of the ions. Journal of Physical Chemistry Letters, 7 19: 4015-4021. doi:10.1021/acs.jpclett.6b01787


Author Burt, Ryan
Breitsprecher, Konrad
Daffos, Barbara
Taberna, Pierre-Louis
Simon, Patrice
Birkett, Greg
Zhao, X. S.
Holm, Christian
Salanne, Mathieu
Title Capacitance of nanoporous carbon-based supercapacitors is a trade-off between the concentration and the separability of the ions
Journal name Journal of Physical Chemistry Letters   Check publisher's open access policy
ISSN 1948-7185
Publication date 2016-10-06
Year available 2016
Sub-type Article (original research)
DOI 10.1021/acs.jpclett.6b01787
Open Access Status Not yet assessed
Volume 7
Issue 19
Start page 4015
End page 4021
Total pages 7
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Abstract Nanoporous carbon-based supercapacitors store electricity through adsorption of ions from the electrolyte at the surface of the electrodes. Room temperature ionic liquids, which show the largest ion concentrations among organic liquid electrolytes, should in principle yield larger capacitances. Here, we show by using electrochemical measurements that the capacitance is not significantly affected when switching from a pure ionic liquid to a conventional organic electrolyte using the same ionic species. By performing additional molecular dynamics simulations, we interpret this result as an increasing difficulty of separating ions of opposite charges when they are more concentrated, that is, in the absence of a solvent that screens the Coulombic interactions. The charging mechanism consistently changes with ion concentration, switching from counterion adsorption in the diluted organic electrolyte to ion exchange in the pure ionic liquid. Contrarily to the capacitance, in-pore diffusion coefficients largely depend on the composition, with a noticeable slowing of the dynamics in the pure ionic liquid.
Keyword Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Physics, Atomic, Molecular & Chemical
Chemistry
Science & Technology - Other Topics
Materials Science
Physics
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID SFB 716
CM1206
102539
DP130101870
ANR-10-LABX-0076
H2020-EINFRA-2015-1-676629
x2016096728
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
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