Hemp-Derived Activated Carbon for the New Generation Zn-Ion Hybrid Supercapacitors

Abstract

In this study, Active carbon material was produced from Hemp-based biomasses (they are called Vezir and Narlı) that are Turkey’s first patented plants to be developed by Academic researchers of Ondokuz mayıs University, Agriculture Department, and were first tested as a cathode material for new trend Zn-ion supercapacitors. The stem parts of the hemp plants were used as a precursor in an attempt to obtain the activated carbon, yielding the final product “ activated carbon” by following hydrothermal, pyrolysis and activation processes with KOH. The solid products obtained in each production step (hydrothermal, pyrolysis, activation process) were characterized by advanced structural characterization techniques such as XRD, SEM, TGA, FTIR, BET and TGA. It has been proven by XRD and TGA analyses that the activated carbon material is synthesized without any impurities. While the surface area of the carbon material obtained as a result of pyrolysis was 280 m2/g, the surface area of activated carbon was found to be 1300 m2/g as a result of activation with KOH. For the electrochemical characterization, the activated carbon was tested in the different electrolytes including Zn-ion via Cyclic voltammetry, Scan rate, and galvanostatic charge/discharge measurements. In addition, the plating/stripping process of metallic Zn plate acting as a cathode was investigated through CV measurement. The activated carbon//Zn hybrid supercapacitor exhibited the best performance in 1M Zn(CF3SO3)2 aqueous electrolyte. The optimized supercapacitor delivered a stable capacity of approximately 220 F/g and an energy density of 65 mWh/g without any loss of capacity over 2000 cycles.