Electrolytic capacitor

An electrolytic capacitor (occasionally abbreviated e-cap) is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor. A solid, liquid, or gel electrolyte covers the surface of this oxide layer, serving as the cathode or negative plate of the capacitor. Due to their very thin dielectric oxide layer and enlarged anode surface, electrolytic capacitors have a much higher capacitance-voltage (CV) product per unit volume than ceramic capacitors or film capacitors, and so can have large capacitance values. There are three families of electrolytic capacitor: aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors.Opened winding of an e-cap with multiple connected foilsCloseup cross-section of an aluminium electrolytic capacitor design, showing capacitor anode foil with oxide layer, paper spacer soaked with electrolyte, and cathode foilConstruction of a typical single-ended aluminium electrolytic capacitor with non-solid electrolyteThe capacitor cell of a tantalum electrolytic capacitor consists of sintered tantalum powderSchematic representation of the structure of a sintered tantalum electrolytic capacitor with solid electrolyte and the cathode contacting layersConstruction of a typical SMD tantalum electrolytic chip capacitor with solid electrolyteAluminum electrolytic SMD 'V' (vertical) chip capacitorsAxial style aluminum electrolytic capacitorsRadial or single-ended aluminum electrolytic capacitorsAluminum electrolytic capacitor with 'snap-in' terminalsAluminum electrolytic capacitors with screw terminalsTypical tantalum SMD capacitorDipped lacquered tantalum “pearl” capacitorsAxial style tantalum electrolytic capacitorsTypical impedance and ESR as a function of frequencyTypical impedance as a function of temperatureElectrolytic capacitorElectrolytic capacitorElectrolytic capacitorBipolar electrolytic capacitorElectrolytic capacitors with non-solid electrolyte have a polarity marking at the cathode (minus) sideElectrolytic capacitors with solid electrolyte have a polarity marking at the anode (plus) side, except for cylindrical leaded (single-ended) and SMD (V-chip) polymer capacitorsCylindrical polymer capacitors have a polarity marking at the cathode (minus) side An electrolytic capacitor (occasionally abbreviated e-cap) is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor. A solid, liquid, or gel electrolyte covers the surface of this oxide layer, serving as the cathode or negative plate of the capacitor. Due to their very thin dielectric oxide layer and enlarged anode surface, electrolytic capacitors have a much higher capacitance-voltage (CV) product per unit volume than ceramic capacitors or film capacitors, and so can have large capacitance values. There are three families of electrolytic capacitor: aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors. The large capacitance of electrolytic capacitors makes them particularly suitable for passing or bypassing low-frequency signals, and for storing large amounts of energy. They are widely used for decoupling or noise filtering in power supplies and DC link circuits for variable-frequency drives, for coupling signals between amplifier stages, and storing energy as in a flashlamp.