Multidimensional design of a cathode electrode composed of a nickel–cobalt carbonate hydroxide and nitrogen-doped pyridine toward high-performance supercapacitors

A three-dimensional (3D) porous NiCo(CO₃)(OH)₂ nanowire composite was fabricated by a facile hydrothermal method and directly grown on a nitrogen-doped, pyridine-based mesoporous carbon substrate to serve as cathode electrode for a supercapacitor. The microscopic structure of this well-organized, independent, nanoscale electrode material exhibited a high electrical conductivity and good ion transportability. The optimized NiCo(CO₃)(OH)₂ composite had a remarkably high specific capacitance of 320.2 mAh g⁻¹ at a current density of 3 A g⁻¹ and excellent cycling stability (84.5 %) maintained after 5000 cycles at a current density of 10 A g⁻¹. An asymmetric supercapacitor fabricated using the optimized NiCo(CO₃)(OH)₂ composite as the positive electrode and graphene as the negative electrode produced a high energy density of 41.1 W h kg⁻¹ and excellent power density of approximately 201.2 W h kg⁻¹ at a current density of 2 A g⁻¹. As a result, this asymmetric supercapacitor was able to power a light-emitting diode. These results suggest that the NiCo(CO₃)(OH)₂ composite on the pyridine-based substrate is a promising candidate for commercial energy storage devices toward the fabrication of high-performance supercapacitors.