Abstract
Lamellar activated carbons derived from Konjac sponges (KACs) have been successfully fabricated through a facile KOH activation method. By manipulating the activation temperature and KOH/C ratio, the achieved KACs exhibit ultrahigh specific surface area up to ∼3000 m2/g and hierarchical pore structure with tunable micro/mesopore distribution. Notably, KACs possess plenty of worm-shaped micropores formed by graphene stacking layers with the lateral distance close to size of hydrated electrolyte ions. Owing to optimized pore structure, high graphitization, and extra O/N doping, KACs exhibited much enhanced specific capacitance (253.0 F/g), superior rate ability (77% retention of capacitance at 10 A/g), and remarkable cycling stability (0.4% decay under 5 A/g after 2000 cycles) in the acid electrolyte. The mass production ability of KAC materials and the knowledge of correlation between texture properties and capacitive performance open new opportunities for the application of such novel biomass-derived carbons in supercapacitor devices.
Highlights
Lamellar activated carbons derived from Konjac sponges (KACs) have been successfully fabricated through a facile KOH activation method
Fabrication of Hierarchical Porous Carbon from Konjac Sponge. e Konjac sponge was firstly crushed and precarbonized in the tube furnace under N2 atmosphere at 500°C for 2 h, and the achieved sample was mixed thoroughly with KOH (C/KOH ratio of 1 : 3). e mixture was carbonized under N2 flow at 700°C, 800°C, and 900°C for 2 h. e resultant products were marked as Konjac derived activated carbon (KAC)- 700, 800, and 900, respectively. e precarbonized sample carbonized under 700°C without the addition of KOH was denoted as UAC
The KOH etching effect became obvious at a high temperature of 900°C and a high KOH/C ratio of 4 : 1, with the observation of the rough surface and plentiful mesopores. e negligible observation of the change of carbon lattice distances for KAC4 may be due to the less-ordered crystalline area from the existence of great deal of mesopores (Figure S5(b)). erefore, the hierarchical porous structure consisting of large amount of graphene layer subnanopore and a portion of mesopores formed due to activation process
Summary
Lamellar activated carbons derived from Konjac sponges (KACs) have been successfully fabricated through a facile KOH activation method. E mass production ability of KAC materials and the knowledge of correlation between texture properties and capacitive performance open new opportunities for the application of such novel biomass-derived carbons in supercapacitor devices. To satisfy the demand of generation SCs for both high-specific capacitance and rate ability, rational design of pore distribution/structure and optimization of surface modification have been urgently required for ACs while maintaining the considerable specific surface area (SSA) [11,12,13]. Erefore, development of well-designed ACs with high SSA, welldesigned pore structure, heteroatom doping, and high graphitization degree opens new opportunities for this sort of traditional materials in future SC devices. Hierarchically porous ACs which inherit the original microstructure and heteroatom can be achieved [22, 23]. us, selection of appropriate carbon precursor and optimization of activation condition become the research hotspot in nowadays
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