In the context of increasing demand for portable electricity-based energy storage, a large amount of research is currently dedicated to supercapacitors and Li-ion batteries. Atomistic simulations are a successful tool to predict and assist the experiment in designing new generation of energy storage devices, if an appropriate simulation methodology and molecular representation are utilized. In this talk we will discuss and compare simulation techniques useful for the study of electrode-electrolyte interfaces. For certain types of problems, such as the dynamics of ions confined inside nanopores, the utilization of explicit electrode polarizability (i.e. the fluctuation local charges on electrode surface) could be very important for prediction the correct behavior. New approaches for simulations that allow to dial-in the desired electrode polarizability will be discussed.  <br/>A comparative study of the structure and dynamics of room temperature ionic liquids (RTIL) and their solutions will be presented. The observed large heterogeneity of the ion dynamics inside nanopores indicate that concurrent slow and fast processes contribute to the charging and discharging of supercapacitors. Analysis of molecular simulations allows us to identify structural correlations (electrode nanostructure, electrolyte composition, etc.) that slow down the underlying mechanisms of ion motions and, therefore, diminish the delivered energy density and power. The role of solvent addition on static and dynamic properties of RTIL-based electrolytes will be also discussed. We will show that solutions of RTILs can behave very differently compared to pure RTILs. For example, a solution of [BMIM][BF4] in acetonitrile solvent will generate a quite different differential capacitance dependence on electrode potential than most RTILs previously studied near flat, rough, and nanoporous electrodes. The difference in dynamic properties (i.e. diffusion coefficients and dynamic electrode-charge-discharge) between [BMIM][BF4] in acetonitrile versus pure RTIL will be also discussed.   <br/>

Ionic liquids at charged interfaces: Static and dynamic properties from atomistic simulations

251st National Meeting (2016)

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