KOH activated carbon derived from biomass-banana fibers as an efficient negative electrode in high performance asymmetric supercapacitor

Abstract

Here we demonstrate the fabrication, electrochemical performance and application of an asymmetric supercapacitor (AS) device constructed with β–Ni(OH)2/MWCNTs as positive electrode and KOH activated honeycomb-like porous carbon (K-PC) derived from banana fibers as negative electrode. Initially, the electrochemical performance of hydrothermally synthesized β–Ni(OH)2/MWCNTs nanocomposite and K-PC was studied in a three-electrode system using 1 M KOH. These materials exhibited a specific capacitance (Cs) of 1327 F/g and 324 F/g respectively at a scan rate of 10 mV/s. Further, the AS device i.e., β–Ni(OH)2/MWCNTs// K-PC in 1 M KOH solution, demonstrated a Cs of 156 F/g at scan rate of 10 mV/s in a broad cell voltage of 0–2.2 V. The device demonstrated a good rate capability by maintaining a Cs of 59 F/g even at high current density (25 A/g). The device also offered high energy density of 63 Wh/kg with maximum power density of 5.2 kW/kg. The AS device exhibited excellent cycle life with 100% capacitance retention at 5000th cycle at a high current density of 25 A/g. Two AS devices connected in series were employed for powering a pair of LEDs of different colors and also a mini fan.