Hydroxyl-rich porous carbons from sulfated sucrose for supercapacitors

Abstract

Using sucrose as a precursor, hydroxyl-rich porous carbons are synthesized by concentrated sulfuric acid pre‑carbonization and further thermochemical activation. The activating agents have significant effects on the physicochemical and electrochemical properties of the resultant porous carbons. Compared with NaOH and K2CO3, KOH delivers the strongest pore etching ability, resulting in a specific surface area of the microporous-dominated carbon (C-PH) as high as 2097 m2 g−1 with a pore volume of 1.62 m3 g−1. In a three-electrode system in a basic aqueous electrolyte, when the mass loading of C-PH is 3 and 5 mg, the specific capacitance of 313 and 295 F g−1 is harvested at 1 A g−1, respectively. In a symmetrical-electrode system, when the mass loading is 3, 5, and 7 mg, the simulated device enclosed C-PH achieves the specific capacitance of 281, 265, and 249 F g−1 at 1 A g−1, respectively. In the case of the corresponding loading mass, the device achieves the energy density of 9.7, 9.3, and 8.6 Wh kg−1 at the power density of 253, 240, and 224 W kg−1, respectively. Results demonstrate KOH has the strongest thermochemical pore-making ability and the resultant hydroxyl-rich porous carbon delivers promising potential in constructing high-performance carbon-based supercapacitors.