Dresden 2020 – wissenschaftliches Programm
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AKE 7.3: Vortrag
Dienstag, 17. März 2020, 10:15–10:30, DÜL
Fluctuating Capacitance in Supercapacitors with curved graphitic Electrodes — •Jannes Seebeck1 and Robert Meißner1,2 — 1Institute of Polymer and Composites, Hamburg University of Technology, Denickestraße 15, 21073 Hamburg, Germany — 2Magnesium Innovation Centre MagIC, Helmholtz-Zentrum Geesthacht, Germany
Supercapacitors are promising storage devices for electrical energy, which storage performance based on a reversible ion absorption by forming an electric double layer on the electrode surface. Using molecular dynamic (MD) simulations, insights into the molecular mechanisms of forming electric double layers and the influence of curved electrodes with varying connected concave and convex parts on the differential capacitance can be obtained. By using the Ewald sum for the calculation of the electrical potential and the potential drop, the differential capacitance for more complex electrode geometries can be determined. This results in capacitance fluctuations with respect to the curvature radius of the separate treated convex and concave parts. Simulations showed a preferential orientation of the adsorbed cations depending on the curvature radius, which can be an explanation for the fluctuating capacitance. By determining the differential capacitance using the free energy approach, it becomes clear that there is also a non-linear dependence between the capacitance, the orientation angles of cations in the double layer and the applied voltage. In this context, design criteria for electrode surfaces, e.g., a favorable mean curvature radius for a specific organic electrolyte, can be developed.