Preparation and performance of novel enhanced electrochemical capacitors based on graphene constructed self-assembled Co3O4 microspheres

Abstract

Transition metal oxide nanostructures is one of the current investigation focuses for supercapacitors. In this paper, self-assembled graphene-constructed Co₃O₄ microspheres (GCM) with controllable diameters, have been successfully synthesized by a one-pot hydrothermal treatment, in which the Co₃O₄ microspheres were simultaneously grown on a large scale on graphene nanosheets. When used as electrode materials for aqueous supercapacitors, the composites of GCM (the volume ratio of graphene oxide and 0.01 M NaOH solution is 15 : 1) exhibited a high specific capacitance of 568.8 F g⁻¹ at a discharge current density of 1 A g⁻¹ in 6 mol L⁻¹ KOH aqueous solution, as well as a good rate capability. It also showed high stability and a high capacitance retention behavior of 95.6% of its initial capacitance was retained even after 2000 cycles. The enhancement of excellent electrochemical performances may be attributed to the synergistic effect of graphene and cobalt oxide components in the unique multiscale structure of the composites.