Zusammenfassung
In the reporting period July 2014 to June 2015, we performed molecular dynamics (MD) simulations with the software packages ESPResSo and Gromacs as well as custom MD-code to investigate different models of room temperature ionic liquids (RTILs) in confined environment and bulk solution. The application in mind is an IL-based electric double-layer capacitor, a non-faradaic energy storage device with advantages in power density and cycle stability over electrochemical cells. In this field, we have developed and applied force fields for ion-ion and ion-electrode interactions on different levels of detail. In 2014, we focused on algorithms for metal boundary conditions in various geometries, needed for realistic modeling of the charging process in a capacitor device. Further, we studied the effects of graphite structure on the adsorbed ions in planar capacitor setups. A possible one-dimensional force field for the interaction between ion and electrode was tested and compared to a fully modeled graphite surface with explicit carbon atoms. This allowed us to show the increased adsorption of the ionic liquid on graphite surfaces due to the texturing influence of the honeycomb pattern. More recently, we performed MD-simulations with electrolyte mixtures and accurate models for carbide-derived carbon electrode systems. In this ongoing work, we study the effect of solvent concentration in ionic liquids on the capacitance of the porous electrode material.
Nutzer
