Fabrication of Low-Cost and Ecofriendly Porous Biocarbon Using Konjaku Flour as the Raw Material for High-Performance Supercapacitor Application

Abstract

Low-cost and ecofriendly porous biocarbons were fabricated from konjaku flour via precarbonization and potassium hydroxide (KOH) activation. The obtained biocarbon AC K -5 derived from a precarbonized carbon/potassium hydroxide (KOH) mass ratio of 1:5 possessed an ultrahigh specific surface area of 1403 m 2 g –1 and hierarchical porous structures with the existence of micro- to macropores. When AC K -5 was employed as a supercapacitor electrode in 6 M KOH, it showed a high specific capacitance of 216 F g –1 and excellent cycling stability with capacitance retention remaining 93.7% after 5000 cycles. Moreover, the AC K -5 sample acquired a supramaximal specific capacitance of 609 F g –1 , and the high energy density of AC K -5//AC K -5 symmetrical cells reached up to 9.2 Wh kg –1 when p -phenylenediamine serving as a redox electrolyte was added into KOH electrolyte. The reported simple fabrication strategy would leverage a green biomass precursor for the preparation of supercapacitors.

Solid waste-derived carbon nanomaterials for supercapacitor applications: a recent overview

“…Micropores ensure high specific surface area and contribute electrical double layer capacitance. To obtain optimized performance, researchers are synthesizing the hierarchically porous CNMs which contain both the mesopores and micropores by adjusting experimental parameters, such as amount of actuating reagent [126][127][128], pyrolysis temperature and pressure [129][130][131][132][133], activating reagents [134][135][136][137][138][139], etc. 31 Fig.…”

Hierarchical Biocarbons with Controlled Micropores and Mesopores Derived from Kapok Fruit Peels for High-Performance Supercapacitor Electrodes

“…Electrodes were composed of porous biocarbons (85 wt %), polytetrafluoroethylene (5 wt %, as binder), and acetylene carbon black (10 wt %). Then, 2 mg of electrode material mixture was pressed onto a clean stainless steel mesh (1 cm × 1 cm) at 10 MPa and dried at 60 °C for 24 h. 49 All works were performed by a CHI660E electrochemical workstation (Chenhua Instrument Co.) at room temperature. A typical three-electrode cell was assembled with Ag/AgCl as a reference electrode, carbon as a working electrode, Pt wire as a counter electrode, and 6 mol/L KOH as an electrolyte solution.…”

“…A symmetrical two-electrode supercapacitor was assembled by two biocarbon electrodes (containing 85 wt % porous biocarbons, 5 wt % polytetrafluoroethylene binder, and 10 wt % acetylene carbon black) in a beaker where the two electrodes were separated by an air-laid paper, and 6 mol/L KOH served as an electrolyte solution. 49 Cyclic voltammetry (CV) was investigated at scan rates of 10, 20, 50, 100, and 200 mV/s. GCD was performed at a current density load of 1, 2, 5, and 10 A/g.…”

“…Electrodes were composed of porous biocarbons (85 wt %), polytetrafluoroethylene (5 wt %, as binder), and acetylene carbon black (10 wt %). Then, 2 mg of electrode material mixture was pressed onto a clean stainless steel mesh (1 cm × 1 cm) at 10 MPa and dried at 60 °C for 24 h …”

High Specific Capacitance Electrode Material for Supercapacitors Based on Resin-Derived Nitrogen-Doped Porous Carbons

“…1−5 Supercapacitors, as a kind of green energy-storage device, have attracted extensive attention because of its high power density, excellent rate performance, and good reversibility along with long durability. 6−10 Furthermore, the electrode materials play a vital role in supercapacitors. 11 Porous carbons of excellent thermochemical stability, low toxicity, good electrical conductivity, and large specific surface area have received extensive attention in electrode materials.…”