A new porous carbon derived from waste Pongamia pinnata oil residue as a renewable resource for supercapacitor performance

A significant portion of ongoing research is focused on transforming biological waste into valuable carbon compounds suitable for use in supercapacitors. However, there is a notable challenge in creating the necessary porous structure and achieving high capacitance. This study aimed to produce a hierarchical porous carbon material through a two-step chemical activation process using the leftover oil-pressed residue from Pongamia pinnata . By combining carbonization with KOH chemical activation, we successfully created a porous carbon substance with a large specific surface area of 811 m 2 g -1 . Through electrochemical evaluations, we identified a notably high specific capacitance of 205 Fg -1 at 1 Ag -1 . In a 1M Na₂SO₄ water-based electrolyte solution, a symmetrical supercapacitor made of this material demonstrated a capacitance of 87.09 Fg -1 at 0.4 Ag -1 , a high energy density of 42.8 Whkg −1 , and a high power density of 9.67 kWkg −1 . Moreover, at a high current density of 10 Ag -1 , the porous carbon material maintained a consistently stable cyclic performance, retaining 93 % of its initial capacitance throughout 5000 charge-discharge cycles. This study underscores the promising potential of utilizing porous carbon derived from oil residue in supercapacitor applications, contributing to the effective utilization of biowaste resources. • A porous carbon symmetric supercapacitor was produced from small-scale industrial waste. •Porous carbon material has a high graphitic nature. •The electrochemical study achieved was higher compared to other industrial waste porous carbon. •Manufacturing porous carbon electrodes might strengthen the reuse of waste for the production of energy storage devices.