What is an Electrolytic Capacitor made of?

 Diagram of an Electrolytic Capacitor

What is an Electrolytic Capacitor and what’s it made of?

Electrolytic capacitors are polarized capacitors whose anode (positive) plate is made of a metal film that forms from an insulating (film) oxide layer through anodization. The oxide layer then acts as the dielectric of the capacitor. A solid, liquid, or gel electrolyte covers the surface of the oxide layer, becoming the cathode (negative) plate of the capacitor and a protective cover of the capacitor.

Due to the thin layer of dielectric oxide and enlarged anode surface, electrolytic capacitors have a much higher capacitance-voltage (CV) product per unit volume than ceramic capacitors or film capacitors, resulting in large capacitance values.

 

The three families of electrolytic capacitors:

 

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