Dual activated carbon derived from Keekar leaves as an excellent symmetric supercapacitor material

Abstract

Porous carbonaceous materials derived from biomass, which are both cost-effective and obtained from sustainable resources, have emerged as appealing electrode materials for energy storage devices. These materials have received great interest as active electrode materials due to their ample, low-cost, sustainable nature and excellent electrochemical stability. In the present work, porous activated carbon (AC) was synthesized from Keekar leaves by dual activation using H2SO4 and KOH. This Keekar leaves derived AC (KLAC) possesses a surface area of ~1677m2g−1 with a combination of micro and mesoporosity displaying a specific capacitance of 411F/g in 6 M KOH and 219.55F/g for 1 M H2SO4 electrolytic solution at a current density of 1 A/g. Further, the symmetric devices were fabricated using both aqueous (aq.) and polymer gel electrolytes for practical evaluation of the material. The aq. and gel device are capable of delivering a specific capacitance of 108.34 F/g and 88.45 F/g, respectively, at a current density of 0.5 A/g. The aq. device offers a maximum energy density of 33.85 Whkg−1 at a power density of 562.5 Wkg−1. The outstanding capacitance retention of 89.5 % is demonstrated by the aq. device at a higher scan rate of 20 A/g after continuous 10,000 charging-discharging cycles. Such high performance and stability make KLAC a potential candidate as an affordable and sustainable electrochemical energy storage application.