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

[Display omitted] ► This is the first attempt to synthesize ACs using five types waste tea-leaves in Chinese. ► As-made ACs have porous structure with high specific surface area up to 2245–2841m2/g. ► As-made ACs all exhibit superior supercapacitive performances in KOH aqueous electrolytes. 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 2245m2g−1 to 2841m2g−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 330Fg−1 at the current density of 1Ag−1. Furthermore, they all show excellent electrochemical cycle stability with ∼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.