Solid coin-like design activated carbon nanospheres derived from shallot peel precursor for boosting supercapacitor performance

Thin porous carbon nanospheres based on natural materials, characterized by abundant availability, facile synthesis without templates, and heteroatom doping have confirmed the enhanced high performance of electrochemical energy storage devices. However, these potentials are difficult to obtain, further poses a serious challenge. This work, activated nanosphere was obtained from biomass precursor shallot peel through solid coin-like design with different chemical impregnations high-temperature pyrolysis. The three activators used were KOH, ZnCl2, NaOH, selected optimize precursor's potential produce nanospheres. All carbons prepared exhibited nano-sized morphological structures content 77.71–90.11%. Furthermore, oxygen 24.60% indicated for electrode material. Surprisingly, KOH impregnation nanosphere-rich structure diameter 102–124 nm adhering nanofiber surface. combination material properties has benefit improving supercapacitor's specific capacitance 170.12 F g−1 in 1 M H2SO4 aqueous electrolyte. Meanwhile, maximum reached 16.67 Wh kg−1 power 86.40 W at constant current density 1.0 A g−1, two-electrode system. Therefore, derived waste is source rich strategy large-scale commercial applications.