Electric double layer theory for room temperature ionic liquids on charged electrodes: milestones and prospects

TL;DR

This review summarizes key theoretical milestones in mean-field models of room temperature ionic liquids on charged electrodes, focusing on differential capacitance and microscopic ion parameters, and discusses recent nonlocal theories addressing overscreening and crowding.

Contribution

It highlights the development of mean-field theories since 2007, emphasizing the role of microscopic ion parameters and recent nonlocal approaches in understanding ionic liquid behavior.

Findings

Differential capacitance profiles are influenced by ion size, polarizability, and dipole moments.

Nonlocal mean-field theories can describe overscreening and transition to crowding.

Milestones include the evolution from classical to advanced nonlocal models.

Abstract

In this review, we shortly summarize the basic theoretical milestones achieved in the mean-field theory of room temperature ionic liquids (RTILs) on charged electrodes since the publication of Kornyshev's seminal paper in 2007. We pay special attention to the behavior of the differential capacitance profile and the microscopic parameters of ions that can have substantial influence on it. Among them are parameters of short-range specific interactions, ionic diameters, static polarizabilities, and permanent dipole moments. We also discuss the recent "nonlocal" mean-field theories that can describe the overscreening behavior of the local ionic concentrations, as well as the crossover from overscreening to crowding.