Classical density functional theory & simulations on a coarse-grained model of aromatic ionic liquids

Microscopic Simulations of Electrochemical Double-Layer Capacitors

Electrochemical double-layer capacitors (EDLCs) are devices allowing the storage or production of electricity. They function through the adsorption of ions from an electrolyte on high-surface-area electrodes and are characterized by short charging/discharging times and long cycle-life compared to batteries. Microscopic simulations are now widely used to characterize the structural, dynamical, and adsorption properties of these devices, complementing electrochemical experiments and in situ spectroscopic analyses. In this review, we discuss the main families of simulation methods that have been developed and their application to the main family of EDLCs, which include nanoporous carbon electrodes. We focus on the adsorption of organic ions for electricity storage applications as well as aqueous systems in the context of blue energy harvesting and desalination. We finally provide perspectives for further improvement of the predictive power of simulations, in particular for future devices with complex electrode compositions.

Density functional theory of confined ionic liquids: the influence of power-law attractions on molecule distributions and surface forces

Interaction energies and density profiles for two model ionic liquids, [C₄mim⁺][BF₄⁻] and [C₄mim⁺][TFSI⁻], confined between charged planar walls are studied within a density functional theory framework. The results of these simulations are also compared with results assuming a simpler linear hexamer–monomer, cation–anion system. We focus attention on the effect on the atom site distributions and the surface forces of an additional, specific attractive potential between oppositely charged molecules. We consider both short- and long-ranged attractive potentials in order to span the degree to which the ionic counterions associate. Independent of its strength, we interpret the results found with the short-ranged potential to be a manifestation of limited molecular association. In contrast, depending on its strength, the results found with the long-ranged potential suggest a much stronger and possibly longer ranged associations of ionic groups. Both potentials are found to influence the behavior of the surface force at small separations, while the long-ranged attractive potential has the greater influence of the two on the long-ranged behavior of the surface force.

Interaction energies and density profiles for two model ionic liquids, [C₄mim⁺][BF₄⁻] and [C₄mim⁺][TFSI⁻], confined between charged planar walls are studied within a density functional theory framework.

Fused coarse-grained model of aromatic ionic liquids and their behaviour at electrodes

A fused coarse-grained model of aromatic ionic liquids 1-alkyl-3-methylimidazoliums tetrafluoroborate ([C_nMIM⁺][BF₄⁻]) has been constructed.

Interfacial structure and orientation of confined ionic liquids on charged quartz surfaces

Atomistic molecular dynamics simulations have been performed to study microscopic ionic structures and orientational preferences of absorbed [BMIM] cations and four paired anions ([BF₄], [PF₆], [TFO] and [TF₂N]) on quartz surfaces.