Aluminum electrolytic capacitor

Aluminum electrolytic capacitors are polarized electrolytic capacitors whose anode electrode (+) is made of a pure aluminum foil with an etched surface. The aluminum forms a very thin insulating layer of aluminium oxide by anodization that acts as the dielectric of the capacitor. A non-solid electrolyte covers the rough surface of the oxide layer, serving in principle as the second electrode (cathode) (-) of the capacitor. A second aluminum foil called “cathode foil” contacts the electrolyte and serves as the electrical connection to the negative terminal of the capacitor.Opened winding of a capacitor with multiple connected foilsCloseup cross-section of an aluminum electrolytic capacitor design, showing capacitor anode foil with oxide layer, paper spacer soaked with electrolyte, and cathode foilConstruction of a typical single-ended aluminum electrolytic capacitor with non-solid electrolyteAl-e-cap with non-solid electrolyteAl-e-cap with solid manganese oxide electrolyte, graphite/silver cathode connectionAl-e-cap with polymer electrolyteAl-e-cap with polymer electrolyte, graphite/silver cathode connectionAl-e-cap with polymer and non-solid electrolyte (Hybrid polymer)Typical impedance and ESR as a function of frequencyTypical impedance as a function of temperature Aluminum electrolytic capacitors are polarized electrolytic capacitors whose anode electrode (+) is made of a pure aluminum foil with an etched surface. The aluminum forms a very thin insulating layer of aluminium oxide by anodization that acts as the dielectric of the capacitor. A non-solid electrolyte covers the rough surface of the oxide layer, serving in principle as the second electrode (cathode) (-) of the capacitor. A second aluminum foil called “cathode foil” contacts the electrolyte and serves as the electrical connection to the negative terminal of the capacitor.