Nanocomposite Electrodes for High-Performance Supercapacitors

We report a new class of nanocomposite electrodes for the development of high-performance supercapacitors with environmentally friendly ionic liquid electrolytes. Having the high-surface-area activated carbons, carbon nanotubes, and ionic liquids as integrated constituent components, the resultant composites show significantly improved charge storage and delivery capabilities. In an ionic liquid electrolyte, the composites possess a superior capacitance (188 F/g) over a pure carbon nanotube electrode (20 F/g) and a conventional activated carbon electrode (90 F/g). On the basis of these nanocomposite electrodes and an ionic liquid electrolyte, we have further developed prototype supercapacitors with a high cell voltage (4 V) and superior energy and power densities (50 Wh/kg and 22 kW/kg, respectively, in terms of the mass of the active electrode material). The nanocomposite supercapacitors developed in the present study clearly outperform the current supercapacitor technology, providing a new approach in fabricating advanced supercapacitors with a high-performance, inherently safe operation and long lifetime.