Synergetic Effect on Electrochemical Performance of Activated Carbon - Multiwalled Carbon Nanotubes Supercapacitor using various Electrodes in Aqueous Electrolyte

Abstract

An Electrical double-layer capacitor (EDLC) has been fabricated with activated carbon (AC) and multi-walled carbon nanotubes (MWCNTs), which in turn were synthesized from Pongamia pinnata fruit shell and its seed oil, respectively. The activated carbon was produced by the chemical activation process at varying carbonization temperatures from 600-900 °C for 5 hours in N2 atmosphere. The obtained activated carbon had a high surface area of 1170 m2 g-1 and a total pore volume of 0.5907 cm3 g-1. The surface area of MWCNTs was 216.1 2 m2 g-1 and the total pore volume was 1.5067 cm3 g-1. The as-prepared AC and MWCNTs were characterized by surface area analysis using Brunner-Emmett-Teller method (BET), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopic analysis, Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HR-TEM), Energy-dispersive X-ray spectroscopy (EDAX) and DFT (Density functional theory). The electrochemical performance of AC-MWCNTs (25:75) Stainless steel (SS) electrode and Graphite sheet electrode (GE) were studied by cyclic voltammetry, Galvanostatic charge-discharge and electrochemical impedance spectroscopy using 0.5 M Na2SO4 aqueous electrolyte. It has shown a specific capacitance of 174 Fg-1 and 95.26 Fg-1 respectively, using the three-electrode system at a current density of 1 mA g-1. The AC-MWCNT (25:75) SS electrode has exhibited excellent specific capacitance (CSP) and its Specific energy density and Power density were greater than AC-MWCNT (25:75) GE. The electrochemical performance of AC-MWCNT (25:75) SS electrode was identified as a suitable, low-cost and promising energy storage device for future generations. The present investigation attempts to promote the supercapacitor device in the context of available and future technologies for alternative energy systems with outstanding performance.