The performance analysis of supercapacitors utilizing chemically activated carbon derived from Chinese medicine residues

Chinese medicine decoction produces large amounts of residue, which must be efficiently recycled for economic and social benefits. Activated carbon was obtained via carbonization–activation using Chinese medicine residues as the raw material and KOH and H₃PO₄ used as the activators. The effect of activator dosage on the as-produced activated carbon was analyzed by changing the activator-to-Chinese medicine residue mass ratio. The characterization of KOH-activated carbon materials revealed that activated carbon materials have a rich pore structure; the specific surface area and pore volume of ZAC-0.75 reached 1258 m²/g and 0.58 cm3/g, respectively. The electrochemical properties of carbon materials were tested to determine their applicability in supercapacitors. Results showed that ZAC-0.75 exhibited the highest capacitance of 239 F/g at the current density of 1 A/g. The specific capacitance retention rate was 98.69% after 10,000 cycles of charge and discharge, indicating good cyclic stability. Using H₃PO₄, with better electrochemical properties, as the activator, the specific capacitance of ZAC-P2 reached 246 F/g at a current density of 1 A/g. The performance of samples activated using both methods exceeded that of commercial carbon YP-50. Thus, the activated carbon prepared using Chinese medicine residues has a very broad application prospect in the field of energy storage materials.