Ion-exchange assisted charge storage via Strategic intercalation of ZnCo2O4/V2O5 heterostructures for high-energy hybrid supercapacitors

Abstract

Designing advanced transition-metal heterostructures with high energy density, high power density, and excellent stability remains crucial for next-generation hybrid supercapacitors. Herein, oxygen-vacancy-enriched ZnCo2O4/V2O5 heterostructures with ion-exchange-assisted V–Co charge storage were fabricated through a simple hydrothermal method. The rational integration of VO into ZCO nanorods enhances crystallinity, generates oxygen vacancies, and enriches surface intercalation sites, leading to enhanced electronic conductivity and redox activity. Structural and surface analyses confirmed the coexistence of multiple valence states (〖Co〗^(2+)/〖Co〗^(3+)) and (V^(4+)/V^(5+)) and a highly crystalline spinel orthorhombic heterointerface, promoting rapid ion diffusion and efficient charge transfer. The optimized ZCO/VO (5 wt%) electrode delivered a high specific capacitance of 2632 Fg-1 at 1 Ag-1 in a three-electrode system, retaining 111% of its initial capacitance after 10,000 cycles due to progressive electrolyte penetration and electrochemical activation. A symmetric device based on ZCO/VO exhibited an energy density of 39 W h kg-1 at a power density of 750 W kg-1, while the asymmetric ZCO/VO//AC cell achieved an outstanding energy density of 102 W h kg-1 at 4050 W kg-1 with 102% stability over 10,000 cycles, successfully powering a red LED for 27 minutes. The superior electrochemical performance stems from the synergistic effect of V–Co ion exchange, a defect-enriched architecture, and enhanced interfacial redox kinetics, underscoring the potential of the ZCO/VO heterostructure as a robust electrode material for high-energy, long-life supercapacitors.