All-Solid-State Supercapacitors Based on Flexible Co3O4 Nanoflowers/rGO Nanocomposites

Abstract

Co3O4 nanoflowers were synthesized by a conventional hydrothermal method at 180°C for 12 h, and flexible Co3O4 nanoflowers/reduced graphene oxide (rGO) nanocomposites were prepared by mechanical mixing with rGO. The all-solid-state supercapacitors (SCs) were constructed using flexible Co3O4 nanoflowers/rGO nanocomposites as electrodes and KOH-PAAK gel as electrolyte. The results show that the obtained SCs have nearly rectangular cyclic voltammetry and linear charge/discharge curves, which indicate its fast electronic migration and response speed. The specific capacitance of the SC is as high as 190 F/g, with an excellent cycling performance (capacitance retention of 90% after 10,000 cycles). The cyclic voltammetrys of SCs are almost unchanged and can work normally when bent from 0° to 180°, exhibiting high flexibility and good reliability of the Co3O4 nanoflowers/rGO nanocomposites. In addition, a green light-emitting diode, electronic watch and electronic scale have been successfully powered by the as-fabricated SCs and can work for several minutes. All the performances have shown that the Co3O4 nanoflowers/rGO nanocomposites could have potential practical applications in the future in flexible energy storage devices.