Direct Growth of 3 D Hierarchical Porous Ni 3 S 2 Nanostructures on Nickel Foam for High‐Performance Supercapacitors

Hierarchical nanostructures grown on conductive 3D scaffold materials are excellent candidates for supercapacitor electrodes. Herein, we report the fabrication and electrochemical performance of 3D Ni 3 S 2 nanoporous structures directly grown on nickel foam via a facile and cost‐effective one‐step process using Ni foam as both the template and Ni source. An ultrahigh areal capacitance of 7.25 F cm −2 was obtained at a current density of 5 mA cm −2 for the nanoporous Ni 3 S 2 structures. The encouraging performance of Ni 3 S 2 nanoporous structures allowed for the fabrication of asymmetric supercapacitors (ASCs) using Ni 3 S 2 as cathode and activated carbon as anode. The resulting ASC exhibited high volumetric capacitance (4.48 F cm −3 at 6 mA cm −2 ), high energy density (1.54 mWh cm −3 at a power density of 0.07 W cm −3 ), and excellent cycling stability (92.7 % retention of the initial capacitance after 5000 cycles at a current density of 16 mA cm −2 ).