Engineering Cu/Ni-O Nanostructures via Bimetallic MOF Conversion for High-Performance Asymmetric Supercapacitors

Rational design of nanostructures composed of mixed-metal oxides synthesized from metal–organic frameworks (MOFs) is a very promising way to enhance the electrochemical performance (EP) of supercapacitor electrode materials. In this work, a porous nanostructured Cu/Ni-O was synthesized via thermal decomposition of bimetallic Cu/Ni-MOF and characterized as battery-type material for application in advanced energy storage systems. Structural characterization showed successful formation of crystalline CuO and NiO with homogeneous distribution of elements inside the nanostructure. Microscopy studies indicated the formation of an interconnected nanoparticle network with a large number of pores and exposed surface sites, which provided favorable pathways for electrolyte diffusion and charge transport. The obtained results have shown significant redox activity linked with the reversible metal–-organic framework. The specific capacity of the prepared Cu/Ni-O material reached the value of 467.1 C/g (129.8 mAh/g) at 0.5 A/g. Moreover, the electrode possessed significant cycling stability with a capacity retention of 88.27% after 9000 GCD cycles and a coulombic efficiency close to 93.8%. For testing the application potential, the Cu/Ni-O//AC hybrid supercapacitor device was prepared employing Cu/Ni-O as a positive electrode and activated carbon as a negative electrode. The assembled Cu/Ni-O//AC device achieved a specific capacity of 205.9 C/g at 0.3 A/g, along with an energy density of 40.1 Wh/kg at a corresponding power density of 212.8 W/kg. Moreover, the device demonstrated notable cycling stability with 94% capacitance retention after 8000 cycles. The increased EP value could be credited to the combined effect of CuO and NiO, the porous structure of MOF-derived material, and charge transfer paths via the nanostructure.