Carbon for Energy Storage Derived from Granulated White Sugar by Hydrothermal Carbonization and Subsequent Zinc Chloride Activation

Abstract

Various electrochemical methods have been applied to establish the electrochemical characteristics of the electrical double layer capacitor consisting of the activated carbon material based electrodes and 1 M triethylmethylammonium tetrafluoroborate solution in acetonitrile and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid as the electrolytes. Activated carbon material used for the preparation of electrodes has been synthesized from hydrochar prepared via hydrothermal carbonization process of granulated white sugar solution in H2O, followed by activation with ZnCl2 with a mass ratio of 1:4 at the temperature 700°C. High porosity and Brunauer-Emmett-Teller specific surface area (SBET = 2100 m2 g−1), micropore surface area (Smicro = 2080 m2 g−1) and total pore volume (Vtot = 1.05 cm3 g−1) have been achieved for the granulated white sugar derived carbon (GWS carbon) material. Wide region of ideal polarizability (ΔE ≤ 3.0 V), short characteristic relaxation time (0.5 s and 4.0 s), high specific series capacitance (125 F g−1 and 140 F g−1) and high energy density (39 W h kg−1 and 48 W h kg−1) have been calculated for the GWS carbon material in 1 M triethylmethylammonium tetrafluoroborate solution in acetonitrile and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, respectively, demonstrating that these systems are very promising for energy storage devices.