Please use this identifier to cite or link to this item: doi:10.22028/D291-28915
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Title: Salt concentration and charging velocity determine ion charge storage mechanism in nanoporous supercapacitors
Author(s): Prehal, Christian
Koczwara, Christian
Amenitsch, Heinz
Presser, Volker
Paris, Oskar
Language: English
Title: Nature Communications
Volume: 9
Issue: 1
Publisher/Platform: Nature Publishing Group UK
Year of Publication: 2018
Publikation type: Journal Article
Abstract: A fundamental understanding of ion charge storage in nanoporous electrodes is essential to improve the performance of supercapacitors or devices for capacitive desalination. Here, we employ in situ X-ray transmission measurements on activated carbon supercapacitors to study ion concentration changes during electrochemical operation. Whereas counter-ion adsorption was found to dominate at small electrolyte salt concentrations and slow cycling speed, ion replacement prevails for high molar concentrations and/or fast cycling. Chronoamperometry measurements reveal two distinct time regimes of ion concentration changes. In the first regime the supercapacitor is charged, and counter- and co-ion concentration changes align with ion replacement and partially co-ion expulsion. In the second regime, the electrode charge remains constant, but the total ion concentration increases. We conclude that the initial fast charge neutralization in nanoporous supercapacitor electrodes leads to a non-equilibrium ion configuration. The subsequent, charge-neutral equilibration slowly increases the total ion concentration towards counter-ion adsorption.
DOI of the first publication: 10.1038/s41467-018-06612-4
URL of the first publication:
Link to this record: hdl:20.500.11880/27814
ISSN: 2041-1723
Date of registration: 17-Sep-2019
Faculty: NT - Naturwissenschaftlich- Technische Fakultät
Department: NT - Materialwissenschaft und Werkstofftechnik
Professorship: NT - Prof. Dr. Volker Presser
Collections:SciDok - Der Wissenschaftsserver der Universität des Saarlandes

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