Effect of carbonaceous support between graphite oxide and reduced graphene oxide with anchored Co3O4 microspheres as electrode-active materials in a solid-state electrochemical capacitor

Abstract

Hydrothermally synthesized Co3O4 microspheres were anchored to graphite oxide (GO) and thermally reduced graphene oxide (rGO) composites at different cobalt weight percentages (1, 10, and 100 wt%). The composite materials served as the active materials in bulk electrodes for two-electrode cell electrochemical capacitors (ECCs). GO/Co3O4–1 exhibited a high energy density of 35 W kg−1 with a specific capacitance (C sp) of 196 F g−1 at a maximum charge density of 1 A g−1. rGO/Co3O4-100 presented high specific power output values of up to 23.41 kW h kg−1 with linear energy density behavior for the charge densities applied between 0.03 and 1 A g−1. The composite materials showed Coulombic efficiencies of 96 and 93 % for GO/Co3O4–1 and rGO/Co3O4–100 respectively. The enhancement of capacitive performance is attributed to the oxygenated groups in the GO ECC and the specific area in the rGO ECC. These results offer an interesting insight into the type of carbonaceous support used for graphene derivative electrode materials in ECCs together with Co3O4 loading to improve capacitance performance in terms of specific energy density and specific power.