Heat-Treated Fe<sub>3</sub>O<sub>4</sub> - Activated Carbon Nanocomposite for High Performance Electrochemical Capacitor

Abstract

The impact of heat treatment temperature on the electrochemical performance of Fe3O4-activated carbon nanocomposite electrodes was investigated using constant current charge-discharge and Electrochemical Impedance Spectroscopy (EIS). An improved capacitive behaviour was observed due to the effect of enhanced ionic and electronic conductivities of the 4 wt% Fe3O4/AC by thermally heating at 200 °C for 6 hours. It was found that the internal resistance of 4 wt% Fe3O4/AC composite electrode calcined at 200 °C for 6 hours is the smallest (2.97 Ω) in comparison to those untreated (4.36 Ω) composite electrodes. The ion mobility inside the porous composite electrodes is favourable at 200 °C, accompanying with the enhanced electronic conductivity of oxide electrode as a result of improved crystallinity. The EIS results and analysis not only have significant impact on the fundamental understanding of the temperature-dependent structural and electrochemical properties of electrode but also provide the insights on the diffusion mechanism of the nanocomposite in neutral Na2SO3 electrolyte.