Supercapacitors have established their role as high-power density devices capable of storing energy for multiple cycles; these devices are more plentiful than batteries. This book outlines the fundamentals of charge-storage mechanisms in different configurations of supercapacitors. It describes the supercapacitor-related phenomena, state-of-the-art supercapacitor technologies, design and fabrication of electrodes, supercapacitor materials, macro-supercapacitor, planar supercapacitor, significance of electrode design, merits, demerits of current technologies, and future directions. It also details related physics, including prospective materials and electrode parameters. Features: Provides understanding of the device architecture, electrode design, and pros-cons of classical supercapacitors Explains material design in the context of electrochemical energy storage Covers state-of-the-art quantum supercapacitor and technological challenges Describes advanced versions of supercapacitor devices, including macro-to-micro scale devices and applications at different scales Includes details of challenges and outlines of future designs This book is aimed at researchers and professionals in electronics, electrochemistry, energy-storage engineering, chemical engineering, and materials science.