Promising activated carbons derived from waste tea-leaves and their application in high performance supercapacitors electrodes

In this paper, five types of waste tea-leaves, which come from five of the most typical tea in China, are first used to prepare activated carbons (ACs) by high-temperature carbonization and activation with KOH. The resulting ACs show typical amorphous character, and display porous structures with high specific surface areas ranging from 2245 m(2) g(-1) to 2841 m(2) g(-1). As the electro-active electrode materials, the as-made five ACs exhibit ideal capacitive behaviors in aqueous KOH electrolyte, and the maximal specific capacitance is as high as 330 F g(-1) at the current density of 1 A g(-1). Furthermore, they all show excellent electrochemical cycle stability with similar to 92% initial capacitance being retained after 2000 cycles. The desirable capacitive performances enable the waste tea-leaves to act as a new biomass source of carbonaceous materials for high performance supercapacitors and low-cost energy storage devices. (C) 2012 Elsevier Ltd. All rights reserved.