Tobacco stalk-derived carbon prepared by one-step molten salt carbonization for supercapacitor

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 m(2) g-1) 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(-1) at 0.2, 0.5, 1, and 2 A g(-1), respectively, acceptable rate performance with 76.6% capacitance retention in range of 0.2-2 A g(-1), and good cyclic stability with 93% capacitance retention after 3000 charge-discharge cycles at 1 A g(-1), as well as energy density of 30.5 Wh kg(-1) at 0.2 A g(-1) and power density of 989.6 W kg(-1) at 2 A g(-1) in 1 mol L-1 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(-1) at 0.2, 0.5, 1, and 2 A g(-1), respectively, and excellent rate performance with 93.7% capacitance retention in range of 0.2-2 A g(-1), as well as energy density of 4.9 Wh kg(-1) at 0.2 A g(-1) and power density of 488.6 W kg(-1) at 2 A g(-1) in 6 mol L-1 KOH aqueous solution using a symmetrical two-electrode system. The correlation between hierarchically porous structure with heteroatom doping and capacitive performance is also discussed.