Construction of Ternary Zn0.5Cu0.5Co2O4 Spinel Structure on Nickel Foam: A Comprehensive Theoretical and Experimental Study from Single to Ternary Metal Oxides for High‐Energy‐Density Asymmetric Supercapacitor Application

Abstract 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 Co 3 O 4 spinel systems on supercapacitor performance is investigated by synthesizing single (ZnO, CuO, Co 3 O 4 ), binary (ZnCo 2 O 4 , CuCo 2 O 4 ), and ternary (Zn 0.5 Cu 0.5 Co 2 O 4 ) oxides on nickel foam substrates. Theoretical and experimental analyses highlight that the flower‐like structures of Zn 0.5 Cu 0.5 Co 2 O 4 , comprising nanowires and nanoribbons, effectively reduced transport barriers and enhanced ion adsorption, thereby improving electron/ion reaction kinetics. Oxygen vacancies induced defect states in Zn 0.5 Cu 0.5 Co 2 O 4 , shifting the d‐ and p‐band center values closer to the Fermi level and enhancing electrochemical performance. The Zn 0.5 Cu 0.5 Co 2 O 4 exhibits a specific capacity of 271 mA h g −1 (1776 F g −1 ) at 1 A g −1 with 97% capacity retention after 5 000 charge/discharge cycles. In a Zn 0.5 Cu 0.5 Co 2 O 4 //activated carbon configuration, the device demonstrates superior energy and power densities of 122.2 Wh kg −1 and 800 W kg −1 , respectively, maintaining 91% capacitance after 10 000 cycles at 30 A g −1 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.