Pencil Peel Derived Highly Porous and Conductive Activated Carbon for All-Solid-State 1.8 V Symmetrical Supercapacitors

Abstract

Activated carbon recycled from biomass resources are recently gaining attention for variety of applications due to their tunable pore size, high specific surface area and good electrical conductivity. Herein, we have synthesized highly porous and conductive activated carbon using commonly available and recyclable pencil peels. The pencil-peel derived activated carbon (PDAC) shows very high specific surface area and good conductivity, therefore becomes suitable to be used as an active electrode material for supercapacitors. The PDAC material is obtained at different temperatures viz. 700, 800 and 900 °C. Among them PDAC-800 shows highest specific surface area and hierarchal pore size while maintaining good conductivity. Due to these properties, PDAC-800 based electrode shows enormous electrochemical performance as compared to its other counterparts. The PDAC-800 electrode possesses high specific capacitance of 552.5 F/g at a current density of 1 A/g using 1 M H2SO4 aqueous electrolyte. Furthermore, an PDAC-800//PDAC-800 based all solid-state flexible symmetrical supercapacitor is assembled using two equally weighted PDAC-800 electrodes, which shows a wide potential window of 1.8 V. Therefore, the as fabricated solid-state device delivers a high energy density of 25.7 Wh/kg with a high-power density of 939.6 W/kg. Meanwhile, the device shows a long-term cycle life of 92.2 % after 5000 continuous charge-discharge cycles. A PDAC-800 based supercapacitor device in PVA-1 M H2SO4 polymer gel electrolyte with 1.8 V potential window is capable to power up a white LED for 3 minutes upon charging for 40 seconds. This work paves the way for the next generation energy storage technology and demonstrate its potential for future supercapacitor application.