CdO nanocubes decorated on rGO sheets as novel high conductivity positive electrode material for hybrid supercapacitor

Abstract

Hybrid supercapacitor devices (HSs) are critical in developing electrochemical energy storage systems with large energy storage capacity and low operating costs. Here, we present the development of novel CdO-rGO nanocomposites, with changing rGO concentrations, as positive electrodes exhibiting outstanding energy storage performance. The nanocomposites were synthesized using a controlled and cost-effective hydrothermal technique. Interestingly, the composite with 25% optimal concentration (from now on referred to as CdO-25%rGO) demonstrated excellent specific capacitance (1195 F g−1 at 1 A g−1) with superior rate performance due to the addition of conductive rGO, allowing quick charge transfer kinetics. Inspired by the outstanding performance, we built CdO-25%rGO//AC HSC that expanded the voltage frame to 2 V when tested in a 3 M KOH alkaline electrolyte. Notably, the fabricated CdO-25%rGO//AC HSC delivered a high specific capacitance of 55 F g−1 at 1 A g−1 and displayed a large energy density of 30 Wh kg−1 at a maximum power density of 5000 W kg−1 coupled with excellent stability (12% capacity fade after 7000 cycles). These findings provide a helpful, logical direction for developing materials with unique compositional properties and electrochemical performance for energy storage applications.