ABSTRACT
Supercapacitors (SCs), also called “ultracapacitors” and “electrochemical capacitors,” have been accepted as one of the most promising energy storage devices owing to their high power density and long cycling life. These excellent properties make SCs a very good complementary device for batteries in certain applications by providing backup power supplies to protect against sudden current density changes in both charging and discharging processes. Besides high power density and long cycling life, SCs also have some other unique advantages such as quick charging, high efficiency, and deep charge and discharge without decreasing the performance or lifetime. This chapter will cover the fundamentals, fabrication, performance characterization, degradation, and theoretical modeling of SCs. Furthermore, the challenge and new designs of SCs will also be discussed.
