| Supercapacitors have been developed as novel energy storage devices between traditional capacitors and batteries, owing to its high energy density, high power density and long cycle life in comparison with traditional capacitors and batteries, respectively. Supercapacitor, as an energy storage device, exhibits a broad application prospect and huge economic value. Due to high specific surface area（SSA）, easy preparation, easily tunable microstructure, diversified morphologies, good conductivity and electrochemical stability, carbonaceous materials are widely used as supercapacitor electrode materials. Biomass materials are renewable, easy visible, low-cost, which is the preferred precursor for the preparation of porous carbon materials. Research and development for porous carbon materials with high SSA and flourishing porous microstructure has been gaining continuous increasing attention for supercapacitor electrode materials research.Soymeal is the by-products in soybean oil extracted processing, which is renewable, easy visible, low-price. Soymeal, especially, enriches in no-carbon atoms of N, O, etc. indicates the unique advantages in terms of the preparation of high specific surface area activated carbon. This paper aims to take advantage of the instability, easy decomposition and escapement of N, O, etc. elements enriched in soymeal, explore the strategy on obtaining high SSA activated carbon. The main research works and results are list as following:（1） Taking advantage of the instability, easy decomposition and escapement of non-carbon elements enriched in soymeal, the strategy is studied to prepare soymeal-derived activated carbon with high SSA and porous microstructure by KOH and Zn Cl2 treatment with less dosage of active agent. The supercapacitor performance of soymeal-derived activated carbon is investigated in alkaline electrolyte.Results show that: One-step activated method with less dosage of active agent is explored to prepare soymeal-derived activated carbon with relatively high SSA and porous microstructure. For example, with 900 oC activated temperature and 1:1 activated ratio, the soymeal-derived activated carbon with a SSA of 2664 m2 g-1 and pore volume of 1.509 cm3 g-1 is obtained, which shows a micro- and mesostructure and a specific capacitance of 195 F g-1 at 5 m V s-1 scan rate in KOH electrolyte.And that the N-enriched soymeal-derived activated carbon is prepared at 900 oC and 1:1 activated ratio by Zn Cl2 activation. The N-enriched soymeal-derived activated carbon（N-content >10 %） has micro- and mesostructure with a SSA of 1091 m2 g-1 and pore volume of 0.562 cm3 g-1, and a specific capacitance of 145 F g-1 at 5 m V s-1 scan rate in KOH electrolyte.（2） Two-step activated method（pre-carbonization and KOH activation） is explored to obtain the soymeal-derived activated carbon with hierarchical pore structure and super high SSA by KOH activation on soymeal char, which is composed of basic graphite crystallite and has initial pore structure.Results show that: After pre-carbonization, soymeal char has a definite strength and initial pore structure. At high temperature（>= 700 oC）, physical activation of CO2 and water vapor, K2CO3 and K2 O secondary activation, and the formation of graphite intercalation compound with K and its compounds are exist during KOH activation process. And that the as-product has an increased-first-and-then-decreased SSA and increasing pore volume. The pore diameter shows the transformation from micropore to mesopore.At 800 oC and 3:1 activated ratio, soymeal-derived activated carbon with super high SSA is obtained, which has a 3798 m2 g-1 SSA and 2.638 cm3 g-1 pore volume. The pore is composed of 12 nm micropore and 35 nm mesopore. The specific capacitance is 300 and 211 F g-1 at 2 m V s-1 scan rate, and has a 3 % and 15 % attenuation of specific capacitance after 10000 cycles in aqueous and organic electrolyte, respectively, which exhibits perfect power properties and cycle stability.（3） O-doping and N-doping are carried out on soymeal-derived activated carbon with super high SSA. The effect of doping process on microstructure, SSA, porosity and supercapacitor performance is investigated.Results show that: The pore structure of super high SSA activated carbon is mainly from the overlap of 12 graphene layers and easy to be burned off during O-doping process with HNO3, which causes the breakup of microstructure, the decrease of SSA and mesopore, the decrease on mesopore diameter from 35 nm to 24 nm, the increase of micropore, and the reduce of specific capacitance and power performance in KOH electrolyte. By studying on the O-doping soymeal-derived activated carbon process with hydrogen peroxide and ammonium persulphate, it is found that the matching between the structure strength of carbon material and oxidant activity should be taken fully into account. Only when the structure strength of carbon material and oxidant activity has well matched with each other, the specific capacitance of carbon material could improve by O-doping process.N-doping is carried out on super high SSA soymeal-derived activated carbon with urea. It is found that urea N-doping process has introduced N-containing functional group and pseudocapacitance, and improved electrical conductivity without breaking the microstructure of activated carbon. With 2:1 N-doping ratio, the specific capacitance of as-product has a notable increase from 304 F g-1 to 437 F g-1（43.8 %） at 5 m V s-1 scan rate in KOH electrolyte, and the internal resistance of electrode is decreased. It indicates that after N-doping, the super high SSA soymeal-derived activated carbon exhibits wonderful capacitance characteristics. |
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