Abstract:

Transition metal oxides are ideal electrode materials used for supercapacitors. However, the synthesis of transition metal oxides suffers from drawbacks such as high reaction temperature and energy consumption. Herein, we report the synthesis of sea urchin-like Co₃O₄-NiO composites supported on graphene oxide (GO) using a hydrothermal method followed by calcination with a low temperature (250 °C). The obtained Co₃O₄-NiO/GO composite demonstrates a high specific capacitance of 883 F g^-1 at 1 A g^-1. Furthermore, upon coupling with an activated carbon (AC) positive electrode, an asymmetric cell of Co₃O₄-NiO/GO//AC exhibits outstanding stability reflected by the high capacitance retention of 82% at a high current density of 10 A g^-1. The excellent electrochemical properties of the composite may be attributed to the good synergistic effect of Co₃O₄ and NiO, as well as the assembly of Co₃O₄ and NiO into a sea urchin structure, which results in increased electron conductivity and more exposed electroactive sites leading to the promotion of the Faradaic redox process.

Key words: Supercapacitor, Co₃O₄-NiO, Graphene oxide, Composite, Electrochemical properties