According the present invention, anode foils are encapsulated in separator material so as to insulate them from the metal housing of an electrolytic capacitor. The present invention also provides for enclosed capacitor configurations for use in stacked capacitor configurations. Preferably, heat-sealable polymeric materials are used as separator materials to encapsulate or enclose the anode assemblies and capacitor configurations. The encapsulated anode assemblies and capacitor configurations of the present invention may be used in implantable cardioverter defibrillators.