Construction of Ternary ZnCuCoO Spinel Structure on Nickel Foam: A Comprehensive Theoretical and Experimental Study from Single to Ternary Metal Oxides for High-Energy-Density Asymmetric Supercapacitor Application.

Developing nanostructured multi-transition metal-based spinel architectures represents a strategic approach for boosting the energy density of supercapacitors while preserving high power density. Here, the influence of incorporating Zn and Cu into CoO spinel systems on supercapacitor performance is investigated by synthesizing single (ZnO, CuO, CoO), binary (ZnCoO, CuCoO), and ternary (ZnCuCoO) oxides on nickel foam substrates. Theoretical and experimental analyses highlight that the flower-like structures of ZnCuCoO, comprising nanowires and nanoribbons, effectively reduced transport barriers and enhanced ion adsorption, thereby improving electron/ion reaction kinetics. Oxygen vacancies induced defect states in ZnCuCoO, shifting the d- and p-band center values closer to the Fermi level and enhancing electrochemical performance. The ZnCuCoO exhibits a specific capacity of 271 mA h g (1776 F g) at 1 A g with 97% capacity retention after 5 000 charge/discharge cycles. In a ZnCuCoO//activated carbon configuration, the device demonstrates superior energy and power densities of 122.2 Wh kg and 800 W kg, respectively, maintaining 91% capacitance after 10 000 cycles at 30 A g with high coulombic efficiency. This study presents an effective strategy to enhance ion/charge transfer and adsorption in multi-transition metal spinel architectures, advancing the development of supercapacitor electrodes.