Use of Coffee Beans to Obtain Activated Carbon with Potential Applications as Supercapacitors

Abstract

Activated carbons (AC) from coffee bean waste were prepared by chemical activation using as activating compounds potassium hydroxide (KOH) and potassium carbonate (K2CO3) respectively, impregnation times of 24 and 48 hours, 600°C and 700°C as temperatures calcination. After that coals samples were synthesized. They were doped with nickel oxide (NiO) in order to modify the electrical properties of the AC. Later they were characterized (physical adsorption of using N2, FT-IR, XRD). The AC/NiO composites were prepared by the chemical method and the electrodes were compacted into pellet forms, which were placed in a two-electrode cell using 2M sulfuric acid (H2SO4) as electrolyte. Activity electrochemical was evaluated by cyclic voltammetry and galvanostatic chronopotentiometry. Finally, the specific capacitance of the supercapacitors (SCS) was determined from AC/NiO. Results of AC/NiO-48-700°C-KOH and AC/NiO-48-700°C-K2CO3 materials showed maximum capacitances of 405.40 and 394.73 F/g respectively.