Ultracapacitor or supercapacitor and sometimes also known as an electric double-layer capacitor (EDLC) is a type of electrochemical capacitor which can store a large amount of energy.

The supercapacitors are being developed comparatively recently, particularly for its use in backup systems and start-up hybrids as an alternative to batteries.

Currently, batteries are considered the best power storage device in electric vehicles (EVs) especially the lithium-ion batteries. Both batteries and ultracapacitors can meet the needs of the automotive industry but in a different manner.

The recent technology is reducing the gap between supercapacitor and batteries. Supercapacitors retain energy in static form instead of chemically storing energy and are able to charge and discharge very quickly than batteries.

On the other hand, batteries use chemical reactions to generate power by using the layers of cells. Their charging process as compared to ultracapacitor is very much slower, depending on size and type. In short, ultra-capacitor in self-discharging processing is efficient than batteries.

Ultra-capacitors development is now moving very quickly. They can play a major role in next-generation electric and hybrid cars as they have the potential to overtake lithium-ion batteries if charging infrastructure supports them.

It is considered a best-suited alternative to electric batteries in the near future. It is a viable solution for electric vehicles where much power is required in a short time. In EVs, the energy can be stored in either batteries or ultra-capacitor. In a case of any emergency i.e for power backup they can be used together.

The major issue with ultra-capacitors is the quick discharge time i.e they cannot hold much charge for longer compared to batteries.