3.3 Contribution of Ion Desolvation to Capacitance
Now
we start to analyze the ion desolvation effect on capacitance. To
validate the feasibility of CDFT in combination with the RPM
coarse-grained model for predicting capacitance, comparisons between the
CDFT calculation and relevant simulation59are performed and shown in Figure 6 . In the simulation, the
electrochemical properties of hard-sphere ions near a planar hard wall
are investigated, in which the relative dielectric constant is set as =
78.50 for mimicking aqueous solution, and a moderate electrolyte
concentration is adopted as = 1.0 M with equal diameters of cation and
anion = 0.40 nm. The system temperature is = 298.15 K. The identical
system parameters are used in the CDFT calculation except that
a
nanoslit with pore width is
applied.
The comparison shows that our coarse-grained-model based CDFT
calculation gives satisfactory predictions on the relation between
surface voltage and surface charge density, and the relation between the
capacitance and the surface charge density except a little overestimate
at the peaks.