High-performance capacitive carbon materials, derived from tobacco stalk, were prepared by a one-step carbonization process in molten carbonate. Owing to the high specific surface area (SSA) (1165.9 m2 g[Formula: see text] and heteroatom doping by the activation effect of molten salt medium for 3 h, the as-obtained carbon material with hierarchically porous structure exhibits an ideal capacitive property with delivering specific capacitances of 219.8, 188.0, 176.4, and 168.4 F g[Formula: see text] at 0.2, 0.5, 1, and 2 A g[Formula: see text], respectively, acceptable rate performance with 76.6% capacitance retention in range of 0.2–2 A g[Formula: see text], and good cyclic stability with 93% capacitance retention after 3000 charge–discharge cycles at 1 A g[Formula: see text], as well as energy density of 30.5 Wh kg[Formula: see text] at 0.2 A g[Formula: see text] and power density of 989.6 W kg[Formula: see text] at 2 A g[Formula: see text] in 1 mol L[Formula: see text] H2SO4 aqueous solution using a three-electrode system. Moreover, it delivers specific capacitances of 143.3, 140.2, 137.4, and 134.3 F g[Formula: see text] at 0.2, 0.5, 1, and 2 A g[Formula: see text], respectively, and excellent rate performance with 93.7% capacitance retention in range of 0.2–2 A g[Formula: see text], as well as energy density of 4.9 Wh kg[Formula: see text] at 0.2 A g[Formula: see text] and power density of 488.6 W kg[Formula: see text] at 2 A g[Formula: see text] in 6 mol L[Formula: see text] KOH aqueous solution using a symmetrical two-electrode system. The correlation between hierarchically porous structure with heteroatom doping and capacitive performance is also discussed.
