Cherry stones as precursor of activated carbons for supercapacitors

It is shown that cherry stones-wastes can be recycled as activated carbons for electrode material in supercapacitors. KOH-activation of this precursor at 800–900 °C is an efficient process to obtain carbons with large specific surface areas (1100–1300 m² g⁻¹), average pore sizes around 0.9–1.3 nm, which makes them accessible to electrolyte ions, and conductivities between 1 and 2 S cm⁻¹. These features lead to capacitances at low current density as high as 230 F g⁻¹ in 2 M H₂SO₄ aqueous electrolyte and 120 F g⁻¹ in the aprotic medium 1 M (C₂H₅)₄NBF₄/acetonitrile. Furthermore, high performance is also achieved at high current densities, which means that this type of materials competes well with commercial carbons used at present in supercapacitors.