Carbon from Fujimoto bean

Abstract

In this paper, we report a method to prepare high-performance porous carbon from the high-yield Fujimoto bean by the process of chemical activation with KOH. The physicochemical properties of porous carbon were characterized by scanning electron microscopy, X-ray diffraction, nitrogen adsorption/desorption, Raman spectroscopy and X-ray photoelectron spectroscopy. The nitrogen adsorption/desorption test demonstrated that KOH has a good pore-making ability (maximum specific surface area of 1,159.95 m(2).g(-1) and a total pore volume of 0.60 cm(3).g(-1)). The porous carbon exhibited excellent performance in symmetric double-layer capacitors, with a high specific capacitance of 219.8 F.g(-1) at a current density of 2 A.g(-1). When the current density increased from 1 A.g(-1) to 10 A.g(-1), the capacitance retention rate reached 84.73%; favourable cycle stability with 96.3% was maintained after 5,000 cycles at a current density of 2 A.g(-1) in an aqueous electrolyte of 6 M KOH. At the same time, the material exhibited a higher energy density (32.292 W.h.kg(-1)) and power density (500 W.kg(-1)). This result suggests that the porous carbon material could serve as an ideal electrode for supercapacitors.