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The structure characteristic of aluminum electrolytic capacitor

January 03,2023

Working medium of aluminum electrolytic capacitors

(1) the working medium ofaluminum electrolytic capacitorsis to form an extremely thin aluminium oxide layer (AL2O3) on the surface of aluminum foil by anodic oxidation. The oxide medium layer and the anode of the capacitor are combined to form a complete system, they are interdependent and can not be independent of each other; the electrodes and dielectric of what is commonly called a capacitor are independent of each other.

The anode of aluminum electrolytic capacitor

(2) the anode of  aluminum electrolytic capacitor  is the aluminum foil with AL _ 2O _ 3 dielectric layer on the surface. The cathode is not the negative foil as we used to think, but the electrolyte of the capacitor.

The negative foil acts as an electrical draw-out

(3) the negative foil acts as an electrical draw-out in the electrolytic capacitor because the electrolyte, as the cathode of the electrolytic capacitor, can not be directly connected to the external circuit, an electrical path must be formed through another metal electrode and other parts of the circuit.

The anodic aluminum foil and cathode aluminum foil of aluminum electrolytic capacitor

(4) They are usually corrosion aluminum foil, the actual surface area is much larger than its surface area, which is also a reason why aluminum electrolytic capacitor usually has a large capacitance. Due to the use of aluminum foil with numerous micro-pits, liquid electrolyte is usually required to make more effective use of its actual electrode area.

The dielectric oxide film of aluminum electrolytic capacitor

(5) It is obtained by anodic oxidation, and its thickness is proportional to the voltage applied by anodic oxidation, the dielectric layer thickness of aluminum electrolytic capacitors can be precisely controlled artificially.

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