High-Performance Porous Carbon Electrodes from Tea Residues: A Sustainable Approach for Advanced Supercapacitors

Carbon electrodes sourced through biomass for application in supercapacitors are currently a significant focus in the development of energy storage devices that prioritize efficiency, environmental sustainability and cost-effectiveness. This investigation highlights a potential avenue for tea residues, concentrating on the conversion of waste to useful resources. Tea residues served as a raw material to produce activated carbon via a simple single-step process, aimed at creating highly efficient electrode material for supercapacitors. The samples were subjected to chemical activation using ZnCl2 at two different temperatures (800 and 900 ºC). Surface area of the two TRAC samples were analyzed using BET technique and noted as 940.14 m2/g and 1158.06 m2/g. The electrochemical investigation was specifically carried out in both aqueous (6 M KOH) and non-aqueous (TEABF4) environments. The TRAC 900 electrode exhibited an impressive specific capacitance of 395.42 F g–1 at 1 A g–1 and displayed exceptional cycling stability, maintaining 96.66% of its capacitance after 16,000 cycles in a non-aqueous environment. Furthermore, the peak power density attained was around 63,000 W kg–1 at an energy density of 35 Wh g–1 when subjected to a higher current density of 10 A g–1. The impressive electrochemical performance suggests that the highly ordered porous carbon electrodes derived from used-tea solid waste represent a promising option for high-performance supercapacitors and exemplify the idea of converting waste into valuable resources.