Chapter eight - Introduction to supercapacitors

Supercapacitors (SCs) have emerged as extremely capable electrochemical energy storage devices. Superior performance characteristics, such as exceptional cyclic stability, ease of handling, operational safety, and superior power density when compared with their counterparts, such as rechargeable batteries, have resulted in attracting immense research interest. Enhanced performance of SCs is attributable to the inherent charge storage mechanism, which is predominantly surface-based for both capacitive types as well as for battery-type electrodes used in electric double layer capacitors (EDLCs) and pseudocapacitors (PCs), respectively. Research in the field of SCs is advancing at an unprecedented pace, followed by these devices finding commercial applications in several fields, including transportation, medicine, defense, electrical storage, and distribution. Furthermore, it is anticipated that with the development of the next generation of SCs, further enhancement in their applicability will be observed.

This chapter will provide a brief overview of the fundamentals of SCs whereas detailed discussions on different aspects of supercapacitors will be provided in more specialized chapters in later sections of this book. The historical and technological evolution of SC as an electrochemical energy storage device will be covered comprehensively. Followed by a discussion on the fundamentals, including classification of SCs based on the charge storage mechanism and cell design. Finally, the functions and desired characteristics of different components of SCs including electrodes, electrolyte, separators, and current collectors, will be reviewed.