Supercapacitor price per kilowatt-hour

High capital cost and low energy density of supercapacitors make the unit cost of energy stored (kWh) more expensive than alternatives such as batteries. Their attributes make them attractive for uses in which frequent small charges/discharges are required (e.g., ensuring power quality or providing frequency regulation).

Supercapacitors are developed within a small industry relative to other types of energy storage, such as batteries. Lithium-ion batteries have become the dominant storage technology for most grid applications through significant investment in innovation and scale-up of deployment, as well as the corresponding increased power densities at less cost.

Electric vehicles are one of the most visible applications of high power density. When an electric vehicle decelerates or brakes, it generates kinetic energy, which can be caught and stored for later use. Supercapacitors work with batteries to swiftly absorb and release energy, giving the power required for rapid acceleration.

Typically supercapacitors are used for their high specific power (W/kg). However, the specific energy of present commercial supercapacitors is lower than that of most batteries. Fig. 2 is a Ragone plot depicting the specific power vs specific energy for a range of different types of electric energy storage devices.

Batteries employ chemical reactions to create electrical energy, while supercapacitors store electrical energy by a mechanism called the electric double layer (EDL) effect. This article will explore the EDL operation of supercapacitor devices in further detail in Section 2, while comparing it to other classes of electrical storage devices.

For example, supercapacitors have a very high cycle life and fast charge/discharge rates but low energy density; lithium-ion batteries have lower cycle life and slower charge/discharge rates but much higher energy density.