The electrode I electrolyte interface is modelled by a mixture of charged and dipolar hard spheres against a planar, charged hard wall. A mean field theory is used to describe the coulombic interactions while steric effects are given by the Percus-Yevick theory. The underlying Percus-Yevick theory for three uncharged species against a planar wall is derived by using the standard method developed by Henderson et al. (D. Henderson, F.F. Abraham, J.A. Barker, Mel. Phys., 31 (1976) 1291) and compared with Monte-Carlo simulations. Although the Percus-Yevick theory has shortcomings, the theory provides an estimate of how the high density of the solvent influences the structural and thermodynamic properties. Consideration of the solvent molecules introduces oscillations in the density distribution of the ions and solvent while the different molecular sizes and ion valences lead to an asymmetry in the differential capacitance.