Composite micelle induced biomass self-assembly into N, S co-doped hierarchical porous carbon spheres with tunable properties for energy storage

Background: Porous carbon spheres are extremely promising for energy storage application. However, how to controllably synthesize heteroatom-doped hierarchical porous carbon spheres in the simple and sustainable method remains a challenge. Methods: The hydrothermal carbonization of soft templates method was applied to synthesize N, S co-doped hierarchical porous carbon spheres (NSHCS) with F127 and TMB as templates, glucose and cysteine as carbon precursors. Significant findings: By changing the amounts of F127 and cysteine, we obtained diverse carbon spheres with different morphologies and structures. Based on the study of the morphology changes of carbon spheres under different conditions, the formation process and synthesis mechanism were proposed. Additionally, the NSHCS electrode presents good specific capacitance of 321.5 F g−1 at a current density of 0.5 A g−1 due to its high specific surface area, heteroatom doping and porous structure. Meanwhile, the assembled symmetrical supercapacitor exhibits an energy density of 12.78 W h kg−1 at power density of 300 W kg−1 in 6 M KOH electrolyte and an energy density of 44.76 W h kg−1 at power density of 1250 W kg−1 in ionic liquid electrolyte.