Chapter 3 - Electrode materials for supercapacitors

Abstract

One of the key challenges faced by this present century is to identify and develop suitable and efficient energy storage devices in order to tap the full potentialities of various renewable energy technologies. In the ongoing pursuit for energy sustainability, supercapacitors are in forefront owing to their superior characteristics, such as high power densities at relatively high energy densities and long cycle life, compared to other storage devices known to date. Supercapacitors are also known as ultracapacitors or electrochemical capacitors, having other advantages compared to batteries. Performance comparison reveals that supercapacitor devices exhibit significantly lower energy storage capability compared to existing commercial batteries. The energy density of commercial supercapacitor cells is limited to 10 Wh kg−1 whereas that of common lead acid batteries reaches 35–40 Wh kg−1, while lithium ion batteries exhibit values higher than 100 Wh kg−1. As supercapacitors are characterized by fast discharge rates and minimum maintenance requirements, these are in demand for frequency regulation applications, apart from their applications in the fields of power electronics, large scale transport systems, energy storage at intermittent power generations, such as wind mills, solar, and tidal renewable technologies.