High-energy supercapacitor based on phosphoric acid (H3PO4)-activated Moringa oleifera leave waste as the electrode material

Abstract

Moringa oleifera-leaves were used as the main starting material for making activated carbon for supercapacitor electrodes. The research focused on producing Moringa oleifera-leaves activated carbon and examining its physical properties and electrochemical performance. The activated carbon was produced through a chemical activation process using 0.5 M H₃PO₄, carbonization under N₂ gas, and physical activation using CO₂ gas. Density measurements showed a decrease from 0.94 g/cm³ to 0.60 g/cm³ following pyrolysis, representing a reduction of 36.17%. Electrochemical testing was performed using cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) methods in a 1 M Na₂SO₄ electrolyte with a current density of 1 A/g. Results obtained within a test voltage window of 0 – 1 V yielded specific capacitances of 45 F/g (CV) and 130 F/g (GCD). Further testing across a wider operating voltage window of 0 – 2 V resulted in a specific capacitance of 153.33 F/g, with a specific energy of 85.18 Wh/kg, and specific power of 1,840 W/kg. These findings demonstrate the potential of Moringa oleifera leaves waste for use as an electrode material in supercapacitors capable of operating at a voltage range of 0 – 2 V, thereby supporting the development of high-energy supercapacitors.