Application of the SRISM approach to the study of the capacitance of the double layer of a high density primitive model electrolyte

TL;DR

This paper uses the SRISM method with HNC and KH closures to study the capacitance of a high-density ionic liquid model's electric double layer, comparing results with simulations.

Contribution

It applies the SRISM approach to high-density electrolytes and evaluates the effectiveness of HNC and KH closures for modeling capacitance.

Findings

HNC closure performs well at moderate electrode charges

KH closure is accurate at high densities but less so at low densities

SRISM results compare favorably with simulation data

Abstract

In this study the Singlet Reference Interaction Site Model (SRISM) is employed to the study of the electrode charge dependence of the capacitance of a planar electric double layer using the primitive model of the double layer for a high density electrolyte that mimics an ionic liquid. The ions are represented by charged hard spheres and the electrode is a uniformly charged flat surface. The capacitance of this model fluid is calculated with the SRISM approach with closures based on the hypernetted chain (HNC) and Kovalenko-Hirata (KH) closures and compared with simulations. As long as the magnitude of the electrode charge is not too great, the HNC closure shows the most promise. The KH results are reasonably good for a high density electrolyte but are poor when applied at low densities.