Electrical Double Layer Capacitors, or supercapacitors as they are often called, are high capacity devices that offer much higher capacitance than other capacitors. These are in high demand, because of the recent boom in electric vehicles. Their structure as well as principle of function is much different, resulting in improved performance. Furthermore, several organic and ionic electrolytes are being investigated to increase capacitance. Let’s examine the structure and principle of function of supercapacitors.
Principle of EDL Capacitor
Aluminum electrolytic capacitors and ceramic capacitors have a conventional dielectric. Supercapacitors, in contrast, lack the dielectric constant as a solid or liquid electrolyte is filled between its two electrodes. An electric double layer is formed in these capacitors between the electrodes and the electrolyte. This works as the dielectric. The capacitance is thus proportional to the layer’s surface area. Activated carbon helps achieve higher capacitance due to the large surface area available for electrodes.Mechanism
Charge and discharge of the capacitor depends on ion absorption and desorption mechanism of electrical double layer. The capacitor is charged when ions are drawn over the electrical double layer by applying voltage to the electrodes. In contrast, they move away from the layer when discharging the capacitor. This is how the process of charging and discharging takes place in supercapacitors.Structure of supercapacitors
The capacitor consists of following three components :- Electrodes
- Electrolyte (plus the electrolyte salt)
- Separator
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