Aluminum Electrolytic Capacitors

Also known simply as electrolytic capacitors, these components use a liquid electrolyte as the cathode and an aluminum oxide layer as the dielectric. Their large capacitance is achieved by electrochemically treating the aluminum foil to create microscopic irregularities, which significantly increase the surface area.

Modern variations include super low ESR (Equivalent Series Resistance) capacitors that replace the liquid electrolyte with solid conductive polymers, offering improved performance and reliability. Additionally, hybrid capacitors that combine electrolytes with conductive polymers have emerged recently, reflecting ongoing advancements to optimize aluminum electrolytic capacitors for specific applications.

An electrolytic capacitor is a polarized device that stores electrical charge using a wet electrolytic solution and a thin oxide film. In aluminum electrolytic capacitors, two closely wound aluminum foil strips serve as the anode and cathode, separated by a spacer soaked in electrolyte. The aluminum oxide layer formed on the anode acts as the dielectric, enabling a high capacitance in a compact size. These capacitors are especially useful in applications where compactness and light weight matter, such as in power supplies, filtering circuits, and various electronic devices.