Thickness analysis of activated carbon electrode of cocoa shell on electrochemical performance of supercapacitors

• Activated carbon was derived from cocoa shell waste for electrode material. • Chemical activation with 0.4 M KOH produced a surface area of 360.290 m²/g. • Electrode thicknesses of 0.4, 0.5, and 0.6 mm were compared for performance. • The 0.5 mm electrode showed the highest capacitance of 366.67 F/g. • BET, SEM, XRD, CV, and GCD analyses confirmed structural and electrochemical quality. • Maximum energy and power densities reached 743.29 Wh/kg and 2678.53 W/kg. • Cocoa shells proved to be a sustainable material for supercapacitor electrodes. • Optimized pore structure enabled effective ion transport and energy storage. Activated carbon was successfully synthesized from cocoa shells with 0.4 M KOH activator with a specific surface area of 360.290 m²/g. This activated carbon will be used as a base material for supercapacitor electrodes. The manufacture of activated carbon from cocoa shells with varying electrode thicknesses has been carried out, namely: 0.4; 0.5; and 0.6 mm. This thickness variation is the first research conducted on activated carbon from cocoa pods. The purpose of the thickness variation is to see its effect on supercapacitor performance. The synthesis of carbon electrodes from cocoa shells was prepared in several stages, namely collecting fruit shells, drying, precarbonation, chemical activation with 0.4 M KOH activator, and pellet molding using a hydraulic press with a pressure of 8 tons. Then the pellets were carbonated using N 2 gas at a temperature of 600 ⁰C and continued with physical activation with CO 2 gas at a temperature of 700⁰ C. The electrochemical performance of the supercapacitor cell was analyzed through a two-electrode system in 1 M KOH solution. The optimum condition was obtained at an electrode with a thickness of 0.5 mm with a specific capacitance reaching 366.67 F/g at a current density of 1.0 A/g, and a maximum energy density of 660 Wh/Kg at an optimum power density of 2378.39 W/Kg. The 0.5 mm thick cocoa shells activated carbon electrode showed high and stable supercapacitor electrochemical energy storage device performance with good material resistance. These results indicate that cocoa pod activated carbon has great potential to be used as a base material for supercapacitor electrodes.