Figure illustrates the characteristic frequency (f c = 1 τ = 1 RC ) as a function of distance from the electrode under various applied potentials. At the electrode surface, f c is initially zero, indicating purely capacitive behavior in the absence of free ions within the Helmholtz layer. Notably, within this region, the relative permittivity is at its lowest due to the highly ordered alignment of water molecules under the intense local electric field. As the system transitions into the compact layer, f c remains near zero, as ion conduction is still negligible due to the scarcity of free ions. In this layer, the relative permittivity gradually increases as the electric field weakens across the Helmholtz and compact layers. Upon reaching the diffusion layer, f c begins to rise due to the increasing presence of mobile ions, peaking in the megahertz range where ionic conduction is most pronounced. Therefore, a CPE behavior can be expected across the frequency range from zero to megahertz due to the coupled distribution of conductivity and permittivity in the compact and diffusion layers. Beyond this peak, f c decreases as ion concentration declines, reducing the number of charge carriers available for conduction. In the bulk electrolyte, f c stabilizes at a value dictated by the ionic conductivity of the electrolyte and the bulk permittivity of the solvent. At frequencies beyond this point, EIS ceases to provide information on interfacial ion dynamics, as the impedance response becomes predominantly governed by the intrinsic dielectric properties of the solvent-water in this case.