Enhanced Electrochemical Performance of Aqueous Zinc-Ion Batteries With Porous Basil-Derived Carbon and Nanostructured MnO₂ Composite Cathodes

This study introduces a novel composite cathode for aqueous zinc-ion batteries (ZIBs), leveraging porous basil-derived activated carbon (BAC) and nanostructured manganese dioxide (MnO₂) synthesized through a one-step hydrothermal process. For the first time, basil-derived carbon is integrated with MnO₂, resulting in enhanced electrochemical performance. The MnO₂/BAC composite delivers a remarkable specific capacity of 237 mAh/g at 0.5 A/g, along with an energy density of 314 Wh/kg and a power density of 0.66 kW/kg, outperforming cathodes made from pristine MnO₂ or BAC. These improvements stem from reduced particle size and a synergistic balance of capacitive and diffusive charge storage mechanisms. Density functional theory calculations corroborate the experimental results, revealing the composite's superior quantum capacity (158.7 µC/cm²) and quantum capacitance (80.4 µF/cm²). Stability assessments highlight excellent cycle life, with > 90% capacity retention and 100% Coulombic efficiency over 300 cycles. The exceptional performance is attributed to the material's unique nanostructure, high surface area (1090 m²/g), and optimized porosity. Additionally, practical applications of ZIBs in pouch cell form using the MnO₂/BAC cathode are demonstrated, showcasing its capability to power a toy car over a satisfactory distance. This study establishes a new benchmark for sustainable and cost-effective cathode materials, significantly advancing ZIB technology for high-efficiency energy storage applications.