Ionic liquids in conducting nanoslits: how important is the range of the screened electrostatic interactions?

Abstract

Analytical models for capacitive energy storage in nanopores attract growing interest as they can provide in-depth analytical insights into charging mechanisms. So far, such approaches have been limited to models with nearest-neighbor interactions. This assumption is seemingly justified due to a strong screening of inter-ionic interactions in narrow conducting pores. However, how important is the extent of these interactions? Does it affect the energy storage and phase behavior of confined ionic liquids? Herein, we address these questions using a two-dimensional lattice model with next-nearest and further neighbor interactions developed to describe ionic liquids in conducting slit confinements. With simulations and analytical calculations, we find that next-nearest interactions enhance capacitance and stored energy densities and may considerably affect the phase behavior. In particular, in some range of voltages, we reveal the emergence of large-scale mesophases that have not been reported before but may play an important role in energy storage.

Theory and Simulations of Ionic Liquids in Nanoconfinement

“…Surprisingly, the Bethe-lattice approximation showed an excellent quantitative agreement with Monte Carlo simulations of the same model (symbols and lines in Figure 6c−e). 43 Most recently, Groda et al 78 revealed that next-to-nearest and higher neighbor interactions in eq 23 can lead to the emergence of large-scale mesophases that have not been reported before.…”

Finding Infinities in Nanoconfined Geothermal Electrolyte Static Dielectric Properties and Implications on Ion Adsorption/Pairing

“…Figure c depicts a lattice model with the Hamiltonian H plasma = 1 / ( 4 π ϵ o ϵ 80 ) ∑ i j 2 N q i q j / | R i j | with equal numbers of monovalent ( q = ±1) cations ( i , j ≤ N ) and anions ( i , j > N ), no checkerboard constraint, no double occupancy, and no lattice water. Lattice models for electrolytes have been previously studied, ,, but to our knowledge not their static dielectric properties. ϵ 80 = 80 strongly screens the Coulomb interactions between the dilute charged lattice particles with a size of 4.5 Å.…”

Setting Boundaries for Statistical Mechanics

“…Ions are crowded where they are most important [184,259] in many systems beyond ion channels and so these issues have attracted much attention in the literature of nanosystems, artificial channels, super capacitors, and so on. Reviews of Jinn-Liang Liu provide a gateway to the immense literature on finite volume effects [186,267] but work is so active [268][269][270], and the literature is expanding so rapidly, that readers must depend on their own searches of the literature. Finite size effects are important in more or less any application involving ions.…”