Sono-exfoliated graphene-like activated carbon from hazelnut shells for flexible supercapacitors

Currently, more than 80% of commercial supercapacitors utilize chemically synthesized carbon nanomaterials which are expensive and necessitates non-renewable resources. Employing renewable, environment friendly and naturally available biomass feedstock as precursor for producing carbon materials is a low-cost and sustainable way for designing the electrodes of supercapacitors. In the present study, high surface area hierarchical porous multilayered graphene-like carbon is obtained via room temperature sono-exfoliation of the activated carbon synthesized via simple and environmentally friendly hydrothermal carbonization and potassium bicarbonate activation of waste hazelnut shells as the precursor. The high surface area graphene-like carbon showed excellent electrochemical performance with specific capacitance of 320.9 F g(-1) at 0.2 A g(-1) current density and exceptional capacitance retention of 77.8% at 2 A g(-1) current density after 10 000 cycles in 1 M Na2SO4 electrolyte. Moreover, flexible supercapacitors fabricated using sono-exfoliated graphene-like activated carbon coated stainless steel mesh electrodes and biopolymer gel electrolyte exhibits an outstanding energy density of 38.7 W h kg(-1) and power density of 198.4 W kg(-1). These results show that mechanically exfoliated graphene-like activated carbon derived from hazelnut shells exhibit superior electrochemical performance that can compete with other activated carbon materials used in energy storage devices for real time applications.

Automated summary

The study demonstrates the successful synthesis of graphene-like carbon material from waste hazelnut shells for supercapacitor electrodes, showing excellent electrochemical performance. It offers a low-cost and sustainable solution for energy storage devices.