Microwave assisted green synthesis of MgO–carbon nanotube composites as electrode material for high power and energy density supercapacitors

Abstract

In the present study, a novel attempt has been made to fabricate an asymmetric supercapacitor based on a MgO–multi-walled carbon nanotube (MWCNT) composite as the cathode and activated carbon (AC) as the anode using an organic electrolyte (1 M LiPF₆ in EC : DMC 1 : 1 by volume). Supercapacitance behavior is examined by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge studies. The results reveal that the test cell displayed excellent capacitance performance between 0 and 3 V. The MgO–MWCNT/AC cell delivers a specific capacitance of 66 F g⁻¹ at a current density of 2.2 A g⁻¹. Cycling studies show that this cell can retain 97% of its initial capacitance after 35 000 cycles. Additionally, the MgO–MWCNT/AC cell also exhibits a maximum energy density of 30 W h kg⁻¹, which is comparable to the values obtained from other supercapacitor configurations. These results encourage utilization of the MgO–MWCNT composite as a potential electrode in developing green and low cost energy storage devices with high energy and power densities as well as prolonged cycle life.