SYNTHESIS AND ELECTROCHEMICAL CHARACTERIZATION OF CARBMATERIALS FROM SUB-BITUMINOUS COAL-DERIVED HYPERCOAL FOR ELECTRIC DOUBLE-LAYER CAPACITORS

Abstract

In this study, we set out to explore a new path for creating high-performance electrode materials for Electric Double-Layer Capacitors (EDLCs), also known as supercapacitors. We focused on carbon powder derived from sub-bituminous coal-derived HyperCoal (SB-HPC), a remarkably pure precursor obtained through a special process. We carefully carbonized this material at different temperatures to craft highly porous carbon structures. Our detailed characterization, using techniques like nitrogen adsorption-desorption, SEM, TEM, XRD, and Raman spectroscopy, showed that these carbons boast impressive specific surface areas (ranging from 1500-2000 m2/g) and a really effective mix of tiny (micropores) and slightly larger (mesopores) channels. When we put these materials to the test in a 6 M KOH electrolyte, they showed excellent capacitive performance. Their cyclic voltammetry curves were almost perfectly rectangular, which is exactly what we look for in ideal capacitive behavior. Galvanostatic charge-discharge tests confirmed high specific capacitances, hitting around 250-280 F/g at 1 A/g, and they held up well even at faster rates. Electrochemical impedance spectroscopy revealed low internal resistance, which is great for power delivery. What's more, these materials demonstrated outstanding long-term stability, keeping over 95% of their initial capacitance even after 10,000 cycles! These exciting results truly highlight the potential of SB-HPC derived carbon as a cost-effective, high-performing, and durable material for the next generation of EDLC electrodes.