On the electrical double layer capacitance of the restricted primitive model: a link between the mesoscopic theory and the associative mean spherical approximation

TL;DR

This paper compares mesoscopic theory and associative mean spherical approximation in predicting electrical double layer capacitance and charge density, showing good agreement at high densities and low temperatures.

Contribution

It links mesoscopic theory with the associative mean spherical approximation for better understanding of electrical double layer properties.

Findings

Good agreement between theories at high densities

Both theories account for charge density fluctuations

Results applicable at low temperatures

Abstract

The results for the electrical double layer capacitance and the charge density of ``free ions'' obtained from the mesoscopic theory are compared with the corresponding results of the associative mean spherical approximation. While the first theory takes into account the fluctuations of the charge density, the second theory assumes that the free ions and ion pairs are in chemical equilibrium according to the mass action law. Our results demonstrate a fairly good agreement between the two theories at high densities and low temperatures.