Supercapacitors: Fundamentals

Supercapacitors are energy storage devices that fall between traditional capacitors and batteries. They are also called electrochemical capacitors or ultracapacitors. Since the 1950s, research on supercapacitors has increased significantly. Capacitors are generally classified into two types: conventional and supercapacitors. Supercapacitors outperform batteries in some areas and serve as a bridge between capacitors and batteries. They can be divided into three main types: hybrid, pseudo, and electrochemical double-layer capacitors. This chapter reviews high-performance supercapacitors made from waste materials across various industries. It covers their history, types, and main uses. Different materials for electrodes and electrolytes can be used in supercapacitors, making each type unique. These devices can be produced cheaply using waste materials such as rice husks, eggshells, banana peels, coal tar, tire scraps, biomass lignin, and circuit board waste. Each kind has its own role and is used in various research fields and industries. They are common in both industrial and electronic applications. Recent progress has led to the development of supercapacitors that utilize nanostructured materials and hybrid designs. These advancements open new possibilities for their use. Supercapacitors are now applied in many areas, mainly for energy management, in medical devices, electronics, energy storage, and industrial processes.