title: The interaction of electric field and hydrostatic pressure in an electrical double layer: A simple "first principle" model that accounts for the finite sizes of counterions.
abstract: A simple model describing the influence of ion size in the electrical double layer (EDL) near a highly charged plane is proposed here. This model is based on the Poisson-Boltzmann equation with a single additional term representing the mechanical response of bulky ions to hydrostatic pressure. This pressure is produced by Coulomb forces, and increases to several kilobars in the vicinity of a highly charged plane. Numerical simulations demonstrate close packing as a limit for counterion concentrations. Differential capacity reaches maximum at 0.1-0.3V and remains reasonably small in wide range of potentials.
authors.affiliation: N.N. Semenov Institute of Chemical Physics RAS, Kosygina 4, 119991 Moscow, Russian Federation. Electronic address: shapoval@chph.ras.ru.
authors.forename: Vladimir L
authors.initials: VL
authors.lastname: Shapovalov
keywords: Electrical double layer; Gouy–Chapman model; Hydrostatic pressure; Ion size effect; Poisson–Boltzmann equation