Facile synthesis of nanowire and rectangular flakes of Co3O4 onto Ni foam for high-performance asymmetric supercapacitors

In this study, Co3O4 with different morphologies (nanowires of single phase, nanowires, and rectangular flakes of both phases) for supercapacitor electrode were synthesized through a hydrothermal approach in the presence of Triton X-100 followed by annealing at 350 °C for 1 h. The different morphologies of the samples were obtained with the assistance of surfactant by adjusting the quantity of reactants. Relative to Co3O4 nanowire (Co3O4 NW) samples, the Co3O4 nanowire-flake (Co3O4 NW-F) samples exhibit excellent electrochemical performance with higher capacity of 1230.65 F g−1 at a current density of 1 A g−1, and with regard to cycling stability, they perform well in a three-electrode system during the larger specific surface area. Moreover, an asymmetric supercapacitor was assembled with Co3O4 NW-F as positive electrode and activated carbon as negative electrode; the device shows a high energy density of 61.60 W h kg−1 at a power density of 1440 W kg−1.