HIGH-POWER ELECTROCHEMICAL CAPACITORS BASED ON CARBON NANOTUBE ELECTRODES

Carbon nanotube sheet electrodes have been prepared from catalytically grown carbon nanotubes of high purity and narrow diameter distributio n, centered around 80 Angstrom. Our study shows that the electrodes ar e free-standing mats of entangled nanotubes with an open porous struct ure almost impossible to obtain with activated carbon or carbon fiber. These properties are highly desirable for high power and long cycle l ife electrochemical capacitors. Specific capacitances of 102 and 49 F/ g were measured at 1 and 100 Hz, respectively, on a single cell device with 38 wt% H2SO4 as the electrolyte. The same cell had a power densi ty of > 8000 W/kg. (C) 1997 American Institute of Physics.