  We investigate the electric double layer formed between charged walls of a
slit-like pore and a solvent primitive model (SPM) for electrolyte solution.
The recently developed version of the weighted density functional approach for
electrostatic interparticle interaction is applied to the study of the density
profiles, adsorption and selectivity of adsorption of ions and solvent species.
Our principal focus, however, is in the dependence of differential capacitance
on the applied voltage, on the electrode and on the pore width. We discuss the
properties of the model with respect to the behavior of a primitive model,
i.e., in the absence of a hard-sphere solvent. We observed that the
differential capacitance of the SPM on the applied electrostatic potential has
the camel-like shape unless the ion fraction is high. Moreover, it is
documented that the dependence of differential capacitance of the SPM on the
pore width is oscillatory, which is in close similarity to the primitive model.
