High-Performance All-Pseudocapacitive Asymmetric Supercapacitor Device Based on a Spinel Co3O4/MWCNT Nanocomposite with Theoretical Insights

The increasing global dependence on energy consumption makes exploring innovative high-performance energy storage solutions more crucial than ever. Supercapacitors are ideal for bridging the gap between traditional capacitors and batteries. A straightforward hydrothermal synthesis approach was used to fabricate the Co3O4/MWCNT nanocomposite as an electrode material. Electrochemical studies show that the Co3O4/MWCNT composite delivers a high specific capacitance of 1000 F/g at a current density of 16 A/g current density. An all-pseudocapacitive asymmetric configuration using Fe2O3-rGO as the anode demonstrates a high specific capacitance of 93.35 F/g at 4 A/g, along with an energy density of 38 Wh/kg and a power density of 7612 W/kg. The asymmetric device exhibits improved cycling stability, with 84% retention in capacitance and a Coulombic efficiency of 97% over 5000 cycles. Density functional theory was employed for a theoretical analysis of the energy storage potential of pure Co3O4 and Co3O4/MWCNT composite structures, focusing on structural and electrical properties. Combining Co3O4 nanostructures with a 1D MWCNT produces synergistic effects and provides a scaffold conducive to high-performance energy storage devices. Co3O4 exhibits a wide range of electrochemical properties, with various forms, porosities, and textures. The surface morphology, increased surface area, and porosity, along with cubic crystal structure features, are critical for the electrochemical performance of Co3O4-based electrodes. The study aims to improve electrode stability and efficiency by optimizing the morphology, porosity, and surface characteristics of Co3O4. It offers key insights into the structure–property relationship and supports the development of scalable, durable electrode materials for next-generation hybrid supercapacitors with high energy and power densities.