ELECTROLYTIC CAPACITOR2

"The overall capacitance of this device is the sum of two series coupled capacitances because the metal electrical contact in the solution will have an electrical double layer. The capacitance of the double layer is even larger than that of the oxide covered electrode because the ""dielectric"" in the double layer is only a few molecular layers of the solvent. Consequently, the overall capacitance is dominated by the lower value of the oxide-covered electrode. "