Electrochemical capacitors or supercapacitors offer a number of advantages over batteries; they are more safe and reliable, charge quicker, have an indefinite lifespan, exhibit a high power density and a wide range of working temperature. Supercapacitors demonstrate an extraordinary potential in both consumer electronics and large-sized energy storage applications, e.g. in communications, transportation, aviation, and power industries. The book explores recent developments in the area of composite applications for supercapacitor electrodes based von conducting polymers, graphene, biomass, or carbonaceous quantum dots. Synthesis strategies of composite materials and electrode preparation methods are discussed in detail.