Nano-Porous ZnCo ₂ O ₄ /CoS ₂ Heterostructured Framework as an Aqueous Asymmetric Supercapacitor

The development of advanced electrode materials with a high energy density and long-term stability is essential for next-generation supercapacitors. Herein, we report the synthesis of ZnCo2O4/CoS2 (ZCO/CS) nanocomposite via a facile two-step hydrothermal route that integrates ZnCo2O4(ZCO) nanorods with CoS2(CS) nanoplates to form a hybrid nanostructure. Structural and surface analyses using XRD, FESEM, TEM, and XPS confirm the successful formation of the ZCO/CS heterostructure with a nanoporous framework. Following BET analyses, an ∼8% increase in specific surface area along with an enhanced nanoscale porosity resulting from CS incorporation into ZCO corroborates the formation of a nanoporous framework. The ZCO/CS electrode exhibits a remarkable specific capacitance of 1722 F g–1 at 0.5 A g–1, nearly twice that of the pristine ZCO, along with superior rate capability as revealed by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The enhanced electrochemical performance of the ZCO/CS electrode can be attributed to the synergistic interaction between ZCO and CS, culminating in a nanoporous architecture that allows better electrolyte accessibility, enhanced bulk electrical conductivity, reduced interfacial charge transfer resistance, and minute lattice expansion, possibly through defect-induced structural relaxation. The asymmetric supercapacitor (ZCO/CS//AC) using 1 M Na2SO4 as the electrolyte delivers a high energy density of 68.6 Wh kg–1 at a power density of 950 W kg–1, retains 94.8% of its initial capacitance after 5000 cycles, and successfully powers an LED. This study underscores the importance of the porous framework of the heterostructure for enhancing cyclic stability and energy storage efficiency, establishing ZCO/CS as a promising electrode material for high-performance supercapacitors.