Low-cost superior symmetric solid-state supercapacitors based on MWCNTs/MnO 2 nanocomposite thin film

Abstract

Abstract Herein we developed a nanocomposite of MnO 2 and multiwall carbon nanotubes (MWCNTs) deposited on a stainless-steel mesh substrate using a simple and scalable chemical approach to greatly expand the capacitive performance of MnO 2 -based electrodes. Electrochemical investigations of the chemically prepared MWCNTs/MnO 2 nanocomposite showed that it has high specific capacitance (614 F/g), high specific energy (85.3 Wh/kg), and high stability over 2500 cycles. The enhanced capacitive performance of the MWCNTs/MnO 2 nanocomposite was analyzed by calculating the surface-controlled and diffusion-controlled charge components. A symmetric solid-state supercapacitor using a MWCNTs/MnO 2 nanocomposite electrode and polyvinyl alcohol (PVA)-Na 2 SO 4 gel electrolyte achieved a cell voltage of 1.0 V and a maximum specific capacitance of 204 F/g with an energy density of 28.33 Wh/kg. Furthermore, the assembled symmetric solid-state supercapacitor achieved coulombic efficiency of 99.04%. The excellent electrochemical features of the MWCNTs/MnO 2 nanocomposite electrode make it a promising material for application in future capacitor-based energy storage systems.