Tunable architecture of cobalt-nickel metal-organic framework/activated carbon composites for superior electrochemical performance in asymmetric supercapacitors.

Cobalt-nickel metal-organic framework/activated carbon (MOF/AC) composites with tunable flower-like architectures were synthesized via a straightforward hydrothermal method, utilizing activated carbon as a structural and functional modifier. This modification increased the surface area from 20.3 m/g to 164.5 m/g, providing a high density of nucleation sites and optimizing the morphology for efficient ion diffusion and electrolyte permeability. The incorporation of activated carbon (AC) not only improved structural stability but also facilitated electron transfer, thereby enhancing conductivity. Among the synthesized composites, MOF/AC-180 exhibited a specific capacitance of 731.8 F/g at 1 A/g, with 67.0 % retention at higher current densities. An asymmetric supercapacitor (ASC) based on MOF/AC-180 achieved an energy density of 35.9 Wh/kg at a power density of 750 W/kg, along with considerable cycling stability, retaining 91 % of its initial capacitance after 10,000 cycles. This study highlights the potential of using ACto enhance the structure and conductivity of MOF composites. The tunable morphology improves ion transport and electrochemical performance, making these materials viable for supercapacitor applications. Furthermore, the straightforward synthesis method and scalability provide a basis for future industrial applications across various multifunctional material fields.