Evolution of Energy Storage on the Platform of Supercapacitors

There has been a major effort, all over the world, to increase an energy density of electrochemical capacitors to meet more demands for electric automotive and regenerative energy storage applications. Hybridizing battery-capacitor electrodes can certainly overcome the energy density limitation of the conventional electrochemical capacitors because they employ both the system of a battery-like (redox) and a capacitor-like (double-layer) electrode, producing a larger working voltage and capacitance. Nanoscience and nanotechnology can provide tremendous benefits to electrochemical energy storage devices, such as batteries and supercapacitors, by combining new nanoscale properties to realize enhanced energy and power capabilities. There are increasing number of published reports on hybrid systems. Several potential strategies to enhance the energy density above that of Gen.1 supercapacitors is now being discussed and some fundamental issues and future directions for Gen.2 & 3 will be identified in near future.