Modulating Oxygen Functional Groups in Activated Carbon for Dual-Ion Adsorption in High-Performance Zinc-Ion Hybrid Supercapacitors

Zinc-ion hybrid supercapacitors (ZIHCs) offer a wide range of applications for portable electronics and emergency energy storage due to their high power density and significant energy density. Nevertheless, conventional activated carbon (AC) cathodes mostly rely on electrical double-layer capacitance (EDLC), which makes it challenging to concurrently attain high energy and power output-a crucial constraint for performance advancements. To overcome this, we present a simple AC modulation strategy that enables precise control of oxygen-containing functional groups (OCFGs) with tunable type and content, while preserving AC pore structure to enhance electrochemical performance. The AC-200//aqueous ZnSO 4 //Zn device (where AC-200 denotes activated carbon treated at 200 °C, and ZnSO 4 is the zinc sulfate electrolyte) exhibits exceptional cycling stability by delivering a specific capacitance of 232.9 F g −1 at 0.1 A g −1 , achieving 104.85 Wh kg −1 at 90 W kg −1 , and maintaining 98.2% capacitance after 5000 cycles, according to electrochemical examination. Epoxy groups promote high spontaneous Zn 2+ adsorption and enhance hydrated Zn 2+ mobility in pores, according to Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations. Additionally, cathode adsorption changes from co-ion to counter-ion adsorption as potential rises, with dual-ion adsorption working in concert to enhance energy storage. This work provides a straightforward and effective approach to designing high-performance ZIHC cathodes.