Sustainable electrode materials for supercapacitors: Recycling Radix Bupleuri residue into high-performance porous carbon composites

Supercapacitors have garnered significant attention due to their high power density, rapid charge-discharge capability, and long cycle life. Biomass-derived porous carbon materials, particularly those from traditional Chinese medicine residues, have emerged as promising candidates for supercapacitor electrodes because of their abundance, low cost, and environmental benefits. In this study, Radix Bupleuri residue, a byproduct of traditional Chinese medicine production, was transformed into porous carbon via pre-carbonization and KOH activation. This approach addresses the recycling challenge of Radix Bupleuri residue and produces a high-performance electrode material with a high specific surface area. To overcome the limitations of poor electrical conductivity in Bupleuri-derived carbon, amino-modified multi-walled carbon nanotubes were incorporated into this porous carbon matrix to form a composite material (RBC/CNT-NH 2 -200). The composite material of RBC/CNT-NH 2 -200 exhibited a specific capacitance of 367.9 F g −1 at 1 A g −1 . The assembled symmetrical supercapacitor by RBC/CNT-NH 2 -200 has a high energy density and power density (9.42 Wh kg −1 at 488.02 W kg −1 ) and outstanding cycle stability (97.27 % after 10,000 cycles). The results highlight the potential of RBC/CNT-NH 2 -200 as a high-performance electrode component for advanced supercapacitors. • A waste-to-resource strategy recycles Radix Bupleuri residue into carbon. • Radix Bupleuri -derived carbon has high specific surface area (2487.15 m 2 g 1 ). • RBC/CNT-NH₂-200 shows excellent capacitance performance (367.9 F g 1 at 1 A g 1 ). • Symmetric supercapacitor has long cycling stability (97.27 % after 10,000 cycles).