Introduction to Green Supercapacitors: Fundamentals, Design, Challenges, and Future Prospects

Abstract

Many efforts have been dedicated to the design of high-energy and power-based green energy storage systems. In this context, supercapacitors with tailored electrode and device architectures are found to be highly appropriate. Recent years have seen supercapacitors attracting worldwide interest due to their critical role in replacing conventional fuels in the transportation sector and also owing to their promising electrochemical characteristics like long cycle life, high power density, and low toxicity. Supercapacitors bridge the gap between conventional dielectric capacitors and primary or secondary Li-ion batteries in terms of their energy and power densities. However, the basic electrochemistry based on how different types of supercapacitors work is less established. Therefore, the underlying charge storage mechanisms, redox reactions, and processes may be confusing. A good supercapacitor electrode material should possess certain characteristics such as large specific surface area and porosity, good surface wettability, high electrical conductivity, tuning of textural parameters, and thermodynamic stability to deliver good electrochemical properties. This chapter discusses the fundamentals of supercapacitors, their classification, and storage mechanisms. This is followed by a brief discussion of various electrode materials used among the different supercapacitor types and their corresponding synthesis and electrochemical progress. Furthermore, the chapter also details the challenges and scope of each of the classifications.