Sustainable porous activated carbon from Polyalthia longifolia seeds as electrode material for supercapacitor application

Abstract

Polyalthia longifolia Seeds (PLS) derived activated carbon (AC) samples were prepared at different temperatures (600, 700, 800 and 900 °C) by the pyrolytic chemical activation route. The as-prepared PLS-ACs were characterized by spectral and analytical tools. The electrochemical characterization studies were performed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and Impedance spectroscopic techniques. A three-electrode system, consisting of the as-prepared PLS-AC samples coated nickel foil (working electrode), Ag/AgCl (reference electrode) and Pt-wire (counter electrode) in 1 M sodium sulfate (Na2SO4) was constructed. The pronounced specific capacitance (Csp) value of 365 Fg−1 was achieved at current density of 1 Ag−1 with reference to PLS-AC sample pyrolyzed at 900 °C with 92% retention even after 5000 charge/discharge cycles, substantiating the significant recycling durability. Furthermore, the prominent electrochemical behaviour under the selected potential window was supportive of its capacitive nature. The low-cost high performance carbon materials, prepared from the bio-waste, exhibited enhanced Supercapacitance, suitable for power storage devices. Moreover, the fabricated symmetric device using PLS-9 showed the high energy density of 27.5 Wh kg−1 at the power density of 499 W kg−1. Thus, the highly porous PLS-9 electrode was noted to a promising candidate for high-performance supercapacitors.