Utilization of carbon-black industry waste to synthesize electrode material for supercapacitors

Solid waste utilization in synthesizing porous carbon materials for supercapacitor electrodes has been a fast-progressing research domain in past decades. Different types of agricultural and industrial waste have the potential to act as a precursor supply for carbon with porous structures. In this study, the waste generated from a furnace-grade conductive carbon black manufacturing industry was utilized to synthesize porous carbon through pyrolysis at 400°C for 2 hours, followed by chemical activation at 800°C for 1 hour. Different activating agents, precisely, potassium hydroxide, orthophosphoric acid, and zinc chloride, were used. Similar activation conditions as well as the mass ratio of activating agent to sample (4:1), were maintained to make a comparative study. All three samples were then tested in a three-electrode set-up through cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy for their performance as electrode material for supercapacitors with a mass loading of 4.0 mg/cm² in 1 M Na₂SO₄ electrolyte. The largest specific capacitance was obtained for the KOH-activated sample, that is, 21.3 F/g, followed by 17.9 F/g for H₃PO₄ activated sample and 13.7 F/g for the ZnCl₂-activated sample, at a scan rate of 50 mV/s. Though the obtained capacitance is much smaller for its practical application, the study acts as a base for further modifications and upgrades to utilize this high carbon-containing waste in energy storage.