Electrolytic Capacitor – Working Principle & Its Applications

An electrolytic capacitor is a capacitor that to produce a higher capacitance than other capacitor types employs an electrolyte.
A liquid or gel that has a lot of ions in it is an electrolyte. Since almost all electrolytic capacitors are polarised, the positive terminal’s voltage must always be higher than the negative terminal’s voltage.
Large capacitance in electrolytic capacitors has various disadvantages in addition to its advantages. Large leakage currents, value tolerances, equivalent series resistance, and a short lifetime are a few of these downsides. Wet-electrolyte or solid polymer electrolytic capacitors are both possible. Although other materials might be employed, tantalum or aluminum are typically used to make them.

With capacitances in the hundreds and thousands of farads, supercapacitors are a unique subtype of electrolytic capacitors, also known as double-layer electrolytic capacitors. The aluminum electrolytic capacitors will be the subject of this paper.
These operate at up to a few hundred volts DC and typically have capacitance between 1F to 47mF. Power supply, computer motherboards, and a variety of home appliances are just a few examples of the many uses for aluminum electrolytic capacitors. They can only be used in DC circuits since they are polarised.

Constructions of Electrolytic Capacitor

Two thin films of aluminum foil are used to make this kind of capacitor, with the insulating oxide layer covering one of the layers. Due to the usage of aluminum foil, the capacitor is frequently referred to as an aluminum electrolytic capacitor.

The two plates are coiled around one another and then put into a container with an electrolyte-soaked paper sheet sandwiched in between them.
Electrolytic capacitors must be forward biassed because of how they are made and the properties of the electrolyte they employ. Consequently, the voltage at the positive terminal must always be greater than that at the negative terminal.
The insulating aluminum oxide, which serves as a dielectric, may become damaged and begin operating as a short circuit between the two capacitor terminals if the capacitor is reverse-biased (if the voltage polarity on the terminals is reversed).
Due to the high current flowing through the capacitor as a result, this could cause it to overheat. The electrolyte warms up and begins to leak or even vaporize when the capacitor overheats, which leads to the enclosure bursting.

Electrolytic capacitors store electric energy statically through charge separation in an electric field in the dielectric oxide layer between two electrodes, similar to other types of conventional capacitors. The cathode, which serves as the second electrode of the capacitor, is theoretically the solid or non-solid electrolyte.

Used in a variety of filtering systems to decrease voltage fluctuations.
When the DC signal is weak when combined with the AC component, filtering is used in output and input smoothing.
They are often utilized in power supply for noise filtering or decoupling.
They are also used to store energy in flashlamps and to couple signals between amplifier stages.