Low-temperature synthesis of sea urchin-like Co-Ni oxide on graphene oxide for supercapacitor electrodes

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 Co 3 O 4 -NiO composites supported on graphene oxide (GO) using a hydrothermal method followed by calcination with a low temperature (250 °C). The obtained Co 3 O 4 -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 Co 3 O 4 -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 Co 3 O 4 and NiO, as well as the assembly of Co 3 O 4 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 .