Binder-free urchin-like 3D ZnCo2O4 nanostructure as a potential electrode for supercapacitors

Abstract

In this paper, reaction temperature-derived innovative nanostructures of ZnCo₂O₄ resemble the shape of urchin-like flowers when grown on 3D nickel foam using a straightforward binder-free hydrothermal method, followed by annealing treatment. These three-dimensional structures are composed of various nanosized petals interconnected on a spherical base, imitating the novel form of an urchin-like flower. This diverse arrangement improves the electrode's structural stability and electrochemical performance through its huge surface area and interconnected porous network. In conjunction with the binder-free design, the combined effects of ZnO and Co₃O₄ ions promote efficient charge transport and successfully modify electrochemistry. Notably, the optimized electrode displays a remarkable specific capacitance of 957.14 F/g (186.11 mAh/g) at a current density of 1 mA/cm² with prominent cycle stability. Moreover, the fabricated symmetric device of ZC120//ZC120 delivered 83.3 F/g (41.6 mAh/g) at 1 mA/cm² with 84.51 % cyclic stability over 10,000 GCD cycles at 30 mA/cm². Overall results suggested that temperature-dependent urchin-like flowers of ZnCo₂O₄ will be a good future choice for energy storage applications.