Fabrication of tobacco-stem-derived hierarchical porous carbon via synergistic gas exfoliation effect for high-performance supercapacitors

The high-value utilization of agricultural and forestry waste holds the promise of alleviating the issues of energy crisis. Among them, the manufacturing of high-performance supercapacitor electrode materials from tobacco waste biomass is a reliable avenue. In this work, tobacco-stem-derived hierarchical porous carbon (TS-HPC) was prepared by one-pot ball milling and carbonization using calcium carbonate (CaCO3) and potassium oxalate (K2C2O4) as mild activating agents. Due to the synergistic activation of CaCO3 and K2C2O4, the specific surface area of TS-HPC is 2749 m2/g. TS-HPC with the hierarchical porous structure greatly shows an excellent specific capacitance (402 F/g at 0.5 A/g) in the three-electrode configuration. In addition, symmetric supercapacitor based on TS-HPC exhibits 10.2 W h/kg energy density at 150.0 W/kg power density, together with outstanding cycling stability (remains 97.8% after 10,000 cycles). Moreover, we demonstrated that the gas exfoliation of CaCO3 and K2C2O4 could contribute to the formation of hierarchical porous structures with a synergistic activation effect. This work could provide a new perspective on the preparation of biomass-derived carbon as electrode for supercapacitors.