A supercapacitor (SC), also known as an ultracapacitor, is an electrochemical energy storage device that stores and releases energy by reversible desorption and adsorption of ions at the interfaces between electrolytes and electrode materials. It is a high-capacity capacitor whose capacitance value is much higher than that of other capacitors, but with a lower voltage limit, which bridges the gap between rechargeable batteries and electrolytic capacitors. Supercapacitors can store 10 to 100 times more energy per unit volume than electrolytic capacitors.
The supercapacitor is used in applications that require many rapid charge and discharge cycles. These applications include cars, trains, buses, elevators, and cranes, where it can be used for short-term energy storage, regenerative braking, and burst-mode power delivery. Batteries offer an improved energy density and have a higher breakdown voltage, while supercapacitors are lighter, possess a longer life expectancy, have more robust operating limits, and have an unparalleled power density. Supercapacitors provide enhanced power density than batteries and higher power density than conventional capacitors.
Its higher capacitance and lower voltage limits make it the perfect choice for a wide variety of electrical systems, from mobile phones to power grids. All-electric vehicles (EVs) employ two distinct types of electric energy storage devices, such as batteries and supercapacitors, to satisfy the needs of the design. Supercapacitors protect batteries from power fluctuations and lead to longer lifespans, whereas batteries provide long-term storage for the energy required by EVs. Thus, with the increasing demand for EVs, the demand for supercapacitors is also increasing.
For example, in August 2021, the U.S. President took a step toward the goal of slashing greenhouse gas emissions with an executive order aimed at making half of all new vehicles sold in 2030 electric, a move made with backing from the biggest U.S. automakers. Electric mobility will also contribute to balancing energy demand, energy storage, and environmental sustainability. This in turn is expected to increase the demand for supercapacitors in the United States.