title: Density functional study of the electric double layer formed by a high density electrolyte.
abstract: We use a classical density functional theory (DFT) to study the electric double layer formed by charged hard spheres near a planar charged surface. The DFT predictions are found to be in good agreement with recent computer simulation results. We study the capacitance of the charged hard-sphere system at a range of densities and surface charges and find that the capacitance exhibits a local minimum at low ionic densities and small electrode charge. Although this charging behavior is typical for an aqueous electrolyte solution, the local minimum gradually turns into a maximum as the density of the hard spheres increases. Charged hard spheres at high density provide a reasonable first approximation for ionic liquids. In agreement with experiment, the capacitance of this model ionic liquid double layer has a maximum at small electrode charge density.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602-5700, United States. doug@chem.byu.edu
authors.forename: Douglas
authors.initials: D
authors.lastname: Henderson
authors.forename: Stanisław
authors.initials: S
authors.lastname: Lamperski
authors.forename: Zhehui
authors.initials: Z
authors.lastname: Jin
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Wu