The development of supercapacitors from coconut-shell activated carbon

In an attempt to develop small high-power supercapacitors a 1 V-70 F, 9 cm(3), coin-shaped supercapacitor was fabricated using coconut-shell activated carbon with a surface area of 1660 m(2)/g and 6 mol/L KOH as the electrolyte. The outer package was made from laminated aluminum foil covered with a nylon insulating layer. The electrochemical behavior was measured by constant current charge/discharge and electrochemical impedance spectroscopy. A specific capacitance of 79 F/g was obtained. Results show that a specific power density of 170 W/kg or 330 W/L, and a specific energy density of 1 Wh/kg can be reached with an excellent discharge performance under high current density.