Nickel-doped Co3O4 spinel nanospheres embedded in nitrogen-doped carbon composites derived from bimetallic NiCo metal–organic framework as a high-performance asymmetric supercapacitor

In this work, nitrogen-doped porous carbon spheres (NCS) with NixCo3O4 composite were derived from a metal–organic framework through a simple hydrothermal method followed by heat treatment. The composition and structure of the resulting Co3O4/NCS and Nix–Co3O4/NCS were regulated by the temperature treatment of nitrogen-doped porous carbon spheres (NCSs) with an organic ligand source. The materials were characterized using a variety of analytical methods such as FE-SEM, XRD, FTIR, XPS, HRTEM, and BET, respectively. The Nix–Co3O4/NCS-2 composite has a high surface area of 198 m2 g−1 and a pore volume of 4.85 cm3 g−1. As-prepared Nix–Co3O4/NCS-2 electrode delivered a high specific capacitance value of 1284 F g−1 at a current density of 1 A g−1 with excellent cycling stability of 96.9% retention after 3000 cycles. Excellent electrochemical performance is due to the synergetic effect of the porous structure and nitrogen-doped carbon. Moreover, an asymmetric supercapacitor was built using Nix–Co3O4/NCS-2 as a positive electrode and MWCNT as a negative electrode, which delivered a maximum power density of 416.7 W kg−1 at an energy density of 26.38 Wh kg−1 with good cycling stability of 92% retention after 3000 cycles. The results demonstrate nitrogen-doped porous carbon spheres (NCS) with Nix–Co3O4 as a promising electrode material for high-performance supercapacitors.