Flower-Like Nanostructured ZnCo2O4/RuO2 Electrode Materials for High Performance Asymmetric Supercapacitors

Abstract

RuO2 is well known to be an active and expensive metal oxide. In the paper, ZnCo2O4/RuO2 nanocomposites were synthesized by simple hydrothermal, impregnation and calcination methods. Due to the multifunctional bridge structure, RuO2 could not only effectively inhibit the volume change of ZnCo2O4 in long-term work but also provide more redox active sites. The forbidden bandwidth was reduced and the conductivity was improved after doping RuO2. Compared with ZnCo2O4, the density of state of ZnCo2O4/RuO2 tended to a higher energy level. ZnCo2O4/3 wt% RuO2 electrode exhibited an excellent specific capacitance (1346.56 F g−1) and cyclic stability in 6 M KOH aqueous solution. For the first time, the electrochemical performance of ZnCo2O4/RuO2//IrO2-ZnO ASC has been evaluated in two-electrode configurations. The supercapacitor exhibited an excellent energy density of 40.89 W h kg−1 at the power density of 740 W kg−1 and a high capacitance retention of 87.5% even after 7000 cycles at a scanning rate of 100 mV s−1. The ZnCo2O4/RuO2 was a promising electrode material for supercapacitors.