Supercapacitor Devices

Abstract

Supercapacitors are electrochemical energy storage devices that can be used to store a large amount of energy. It delivers excellent electrochemical performances such as high capacitance, high power density, and long cyclic stability at low cost. In contrast with other energy storage devices, its charge storage mechanism is simple, which makes its charging and discharging process highly reversible. Based on the charge storage mechanism, its electrode material can be categorized as EDLC and pseudocapacitor. EDLC capacitor stores charge electrostatically whereas, reversible redox reaction occurs in pseudocapacitance. Here, the charge is stored via the Faradaic process. The further improvement in the performance is done by the formation of composite electrode material, the introduction of nanostructure electrode, assembling a hybrid capacitor by introducing battery electrode material, and assembly of an asymmetric supercapacitor. Various combinations of electrode and electrolyte material in different types of configuration provide a synergistic effect of both types of charge storage mechanism and wide operating potential range. The main aim is to obtain a high energy density device without compromising other parameters such as power density, rate capability, and cyclic stability. This chapter extensively deals the various materials used in supercapacitors, types of charge storage mechanisms, types of supercapacitor assembly i.e., symmetric supercapacitors, asymmetric supercapacitors, battery-supercapacitor hybrid devices, etc., and their performance to the type of electrode material.