Redox additives dependent supercapacitor performances of ZnO/SnO2@MWCNT nanocomposites

Abstract

The poor cyclic stability arose from the low conductivity and strong electrostatic interaction between the ions remain the formidable challenge on the development of ZnO/SnO2 based electrodes for high-performance supercapacitor devices. Herein, an effective strategy was developed to achieve the higher conductivity by the growth of ZnO/SnO2 nanocomposites (NCs) on multiwalled carbon nanotube (MWCNT) through hydrothermal approach. Physiochemical characteristics of the synthesized ZnO/SnO2@MWCNT (ZSM) NCs were investigated by the XRD, FT-IR, SEM, HR-TEM, and XPS analyses. The fabricated working electrodes performances were examined for supercapacitor devices under pure 1 M Na2SO4 (NSE) and 0.1 M K4[Fe(CN)6] added redox additive electrolytes (RAE). The fabricated working electrode showed 297 Fg−1 specific capacitance in NSE and it was increased to 3885 Fg−1 under RAE. The fabricated working electrode possessed the cyclic retention of 81.15 % even after consecutive 5000 GCD cycles and it was enhanced up to 84.42 % in RAE. Also, incorporation of redox additives, greatly enhanced the energy and power densities of the fabricated device and they were found to be 22.50 Whkg−1 and 3200 Wkg−1, respectively in RAE. It confirmed that the incorporation of MWCNT in electrode material and RAE, greatly improved the overall efficiency of the ZnO/SnO2 based supercapacitors.