Powerful energy storage technologies are needed to satisfy the increasing demands and requirements in the energy sector, especially in the context of sustainable energy supply. In the last decade, electrochemical double layer capacitors (EDLCs) have been used in commercial applications due to their exceedingly high power density and long-term stability. The use of EDLCs is currently restricted to specific application, because their low energy density and comparably high production costs hamper a more widespread applicability. For designing improved devices, material properties of the base compounds and their complex interplay need to be known and understood. In particular, transport and rheological properties of electrolytes are of main relevance for technical applications.<br/>In this context, molecular modeling can provide essential insights and speed-up development time by focusing experimental tests on the most promising candidates. Force field-based approaches have been proven highly useful for predicting material properties The availability of consistent and proper force field parameters is unfortunately not always guaranteed. In particular, ionic species typically represent a challenging class of materials. A tailored force field which can be easily augmented helps to overcome limitations of traditional force fields. We present molecular dynamics simulations using a new tailor-made force field (TMFF) and compare its performance to common force fields and quantum chemical calculations.<br/>Molecular dynamics simulations demonstrate that the percentage deviation from experimental liquid densities is reduced by over 5 % using TMFF compared to conventional force fields and that calculated transport and rheological properties can achieve accuracies of Drude-based polarizable models. Our results show that the new, easily extendable force field is capable to reliably predict trends and material properties of ionic liquid-based electrolytes which are of main importance for a broad variety of technical applications.

Molecular modeling of ionic liquid-based electrolytes

2019 Fall National Meeting

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