Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 56: Focus: Computational Methods for the Energy Transition: Paving the Road to Future Materials and Storage Systems - organized by Stephan Kramer and Jochen Zausch
CPP 56.6: Vortrag
Donnerstag, 4. April 2019, 17:15–17:30, H14
Simulating Curved Graphene Supercapacitors — •Jannes Seebeck1 and Robert Meissner1,2 — 1Hamburg University of Technology, Institute of Polymer and Composites, Hamburg, Germany — 2MagIC Magnesium Innovation Centre, Institute of Materials Research, Helmholtz Zentrum Geesthacht, Geesthacht, Germany
Supercapacitors are promising storage devices for electrical energy that offers a high power density but typically low energy density. Their storage performance is due to a reversible ion absorption by forming an electric double layer on the electrode surface. Molecular dynamics (MD) simulations offer the possibility to gain insights into the molecular mechanisms of forming electric double layers and pore filling. However, simulations show that in supercapacitors with an ionic liquid as electrolyte, the mean-field approach for calculating the differential capacitance leads to false results due to the strong correlation of ions. By using a free energy approach for the calculation of the differential capacity from the fluctuating charge density on the electrode surfaces it is possible to show a non-linear behaviour of the ionic liquid on the capacitance. Furthermore, MD-Simulations show a different orientation of the ionic liquid to the electrode interface depending on the applied potential, which can be a reason for the fluctuation of the capacity. By simulating curved graphitic electrodes, with a convex and concave pore-like structure, in combination with a diluted ionic liquid as electrolyte it is possible to examine the impact of curvature on the orientation of the ionic liquid, and finally the resulting capacity.