Can aluminum foil be used as a capacitor anode?

Only during the late 1930s the hard-rolled aluminum foil was found to be able to provide capacitor anodes of improved capacitance. This property had not found any use until the 1960s when the aluminum electrolytic capacitor first appeared in the electronic industry.

How are aluminum electrolytic capacitors made?

Aluminum electrolytic capacitors are made of two aluminum foils and a paper soaked in electrolyte. The anode aluminum foil is anodized to form a very thin oxide layer on one side and the unanodized aluminum acts as cathode; the anode and cathode are separated by paper soaked in electrolyte, as shown in Fig. 8.10A and B.

How does aluminum foil affect the capacitance of a capacitor?

The aluminum foil which forms the anode of the capacitor will have its surface chemically highly etched to increase its surface area, and therefore its capacitance.

Are aluminum foil capacitors bulky & heavy?

Until the wound construction of aluminum foil capacitors, this type of capacitor was bulky and heavy. There are different sizes of capacitor ranging from 3 mm in diameter for 5 mm in height up to 90 mm for 210 mm .

Can aluminum electrolytic capacitors be used in AC circuits?

Therefore, do not use aluminum electrolytic capacitors in any of the AC circuits. Aluminum electrolytic capacitors are sensitive to contamination of halogen ions (especially to chlorine and bromine ions) though the degree of the effect depends on the properties of the electrolyte and/or sealing materials used in the capacitors.

Are aluminum electrolytic capacitors polarized or asymmetrical?

In general, an aluminum electrolytic capacitor is asymmetrical in structure and polarized. The other capacitor type known as a bi-polar (non-polar) comprises the anodic aluminum foils for both electrodes.