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Differences Between Capacitor & Battery

Comparison & Differences Between Capacitor, SuperCapacitor & Battery

Capacitors & batteries both operate similarly considering they both store & provide charge. However, there are some important differences in their charging & discharging characteristics that define their usage & applications.

Differences Between Capacitor & Battery

Capacitor:

A capacitor is a passive electronic component made up of two conductive plates & an insulator (dielectric) in-between. It stores charge between its plates in the form of an electric field.

When a current is supplied to the capacitor, the dielectric stops the current flow, due to which, the charge builds up between the plates as an electrostatic field.

Supercapacitor:

Supercapacitors are considered between capacitors & batteries. It consists of two metal plates (electrodes) with an electrolyte in-between. There is an ion-permeable membrane between the plates that allow the transfer of ions.

It stores energy between the ions of the electrolyte & electrode in a double layer of charge. When the voltage is applied to the supercapacitor, the ions inside the electrolyte build up upon each electrode. There are no chemical reactions between the electrolyte & electrode.  

Battery:

The battery is an active component made up of two types of metal plates called Anode (positive terminal) & Cathode (negative terminal) & an electrolyte.

It stores charge in the form of chemical energy through chemical reactions between the electrodes & the electrolyte. This chemical energy converts into electrical energy and provides a constant voltage across its terminals. The fact that it stores charge in its electrolyte which provides a large volume for charge storage, increase its charge capacity tremendously.

Comparison/Differences:

  • A capacitor stores energy in an electrical field between its plates while a battery stores energy in a chemical form by means of chemical reactions.
  • A capacitor can charge & discharge quickly as compared to a battery because the chemical reactions inside a battery take a certain delay to convert into electrical energy & vice versa.
  • During discharging, the output voltage of a capacitor decrease linearly. However, the battery provides a constant output voltage.
  • The fact that the battery stores energy in chemical form provides high energy density than a capacitor.
  • The batteries have a limited current & voltage ratings while capacitors can withstand heavy load currents and voltages.
  • The capacitors have high leakage current compared to a battery.
  • Capacitors have high-temperature tolerance while batteries are more temperature sensitive.
  • The size of the battery is comparatively small as compared to capacitor considering they have same charge capacity.
  • Batteries have limited life cycles of approximately 500 while the capacitors have longer life cycles.
  • A battery is used in DC circuits while capacitors are used in DC as well as AC circuits.
  • The battery can store charge for a long duration thus it is used as a primary source for powering circuits. While the capacitor holds the charge for a short duration thus it is not used as a source.
  • A capacitor can withstand heavy current & voltage spikes which makes it a good surge absorber while the battery cannot tolerate high voltages and current.

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