Enhanced supercapacitor performance of ZnO/SnO2:rGO nanocomposites under redox additive electrolyte

Abstract

Supercapacitor performances of ZnO/SnO2 mixed metal oxides (ZS) and mixed metal oxides loaded reduced graphene oxide (ZnO/SnO2:rGO - ZSR) nanocomposites (NCs) were reported. A simple one-pot hydrothermal method was adopted to prepare ZS and ZSR NCs and the prepared NCs were analytically characterized by XRD, SEM, FT-IR, XPS and HRTEM analyses. XRD analysis confirmed the presence of hexagonal-structured ZnO and orthorhombic-structured SnO2 nanoparticles in ZS and ZSR NCs, respectively. The presence of ZnO nanospheres and SnO2 nanorods loaded rGO nanosheets were identified by SEM and HRTEM analyses. The electrochemical characteristics of the ZS and ZSR NCs were tested under 1 M Na2SO4 (NS) and redox additive electrolytes (RAE). The ZSR NCs modified working electrodes possessed the superior specific capacitance of 3238 Fg−1 in RAE with the electrochemical capacitance retention of 91.54% after 5000 GCD cycles. Similarly, the fabricated ZSR NCs-based asymmetrical supercapacitors revealed the highest specific capacitance of 89.19 Fg−1 with the energy and power density values of 17.34 W h kg−1 and 2000 W kg−1, respectively under redox additive electrolytes.