High-performance supercapacitor electrodes for energy storage using activated carbons from argan husks, date seeds and olive stones

Electrochemical performances of three electrodes (E) fabricated using activated carbons (AC) derived from agricultural biomass waste, specifically argan husks (ah), date seeds (ds) and olive stones (os), denoted ACah-E, ACds-E and ACos-E respectively were evaluated. These activated carbons were produced through a combination of thermal and chemical methods, involving carbonization for 2 hours at a temperature of 900 °C, followed by chemical activation using phosphoric acid as the activating agent. The scanning electron microscope observations revealed that the obtained samples exhibited variable pore size distributions tailored based on the raw materials activated by the same process. Subsequently, cyclic voltammetry, galvanostatic charge-discharge, and electro­chemical impedance spectroscopy were used to characterize the electrochemical performances of ACah-E, ACds-E and ACos-E as supercapacitor electrodes. The results revealed that the ACah-E, ACds-E and ACos-E cells have specific capacitances of 138.26, 50.41 and 34.61 F/g, respectively. These results were found to be influenced by the specific surface areas, which were 476 m²/g for ACah, 441 m²/g for ACds and 362 m²/g for ACos, as determined by the BET method. The behaviour of electrochemical double-layer capacitors (EDLC) in acidic aqueous electrolyte (1 M H2SO4) is demonstrated by these findings, which suggest that the waste materials used may also be prospective candidates for supercapacitor applications, with the best performance for ACah-E than other.