Exploring the Rational Design and Strategy of Metal Ion‐Integrated 3D Hierarchical Spinel Oxide Nano/Microarchitecture for Battery‐Supercapacitor Hybrid Energy Storage System

The synergistic interaction and strategic manipulation of electronic structures by incorporating metal ions into the host matrix have captivated research efforts for supercapacitors. This study presents an efficient strategy for synthesizing Cu‐ion‐incorporated NiCo 2 O 4 (CNCO) nano/microarchitectures using a hydrothermal method followed by heat treatment. It establishes a clear link between variations in Cu content and their effects on material properties, which influence electrochemical performance. Optimizing the Cu content enhances ion transport and conductivity, while creating active sites for faster charge transfer. The porous framework boosts structural integrity and mass transport, reducing aggregation risks. Enhanced performance stems from synergistic interactions between Cu and the NCO matrix in the CNCO nano/microarchitecture. The experimental findings are further substantiated by computational analyses utilizing density functional theory (DFT) calculations. Impressively, the regulated CNCO electrode material exhibits a remarkable specific capacitance of 1301 F/g at 1 A/g and a rate capability of 81.3% at 20 A/g, significantly outperforming other CNCO variants. The optimized CNCO electrode material contributes to a high‐performance battery‐supercapacitor hybrid system, achieving an energy density of 61.36 Wh/kg at a power density of 1.18 kW/kg, with excellent cyclic stability. This system illuminates green and pink light‐emitting diodes.