Abstract: A substantially flat electrolytic capacitor capable of retaining several joules of energy has anode and cathodes held together by a solid or elastomeric solid adhesive which is also the electrolyte within the capacitor.

Abstract: A compact multiple anode electrolytic capacitor suitable for an implantable defibrillator includes three or more layers of an anode using a combination of tunnel etched anodes on the outer layer and a layer of highly etched foil with a solid core in the center. By means of this and similar multiple anode arrangements the capacitor achieves a smaller volume overall. The arrangement further allows the electrolyte and thus the conducting ions to reach the whole surface area of the anode, even pores which originate on the inner layer of the foil, yet at the same time the ions are not able to penetrate all the way through the foil. More layers of anode can be used in the sandwich depending on the desired electrical performance. The high energy density renders the capacitors highly suitable for use in technologically sophisticated biomedical electronic devices such as cardiac pacemakers and defibrillator implanted in the human body.