Differential Capacitance of Electric Double Layer – Influence of Asymmetric Size of Ions, Thickness of Stern Layer and Orientational Ordering of Water Dipoles

Abstract

The mean-field theoretical model of the electric double layer which takes into account the asymmetric finite size of anions and cations and the orientational ordering of water dipoles in the Stern and the diffuse layers is described together with a short description of the main concepts and a brief review of the literature in the theory of the electric double layer. As an example of the application of the described mean-field lattice model of the electric double layer, the influence of different sizes of anions and cations, the influence of the thickness of the Stern layer and the influence of the orientational ordering of water molecules on the asymmetric, bimodal camel-like dependence of differential capacitance on the surface potential is theoretically considered.

The presented theoretical model of the electric double layer is flexible enough to be in the future extended to more complicated multicomponent systems with molecules of different sizes and the orientational ordering of molecules.