Discrete V2O5/NCQDs heterogeneous assemblies synergizing built-in fields and confinement for enhanced aqueous zinc ion storage

Abstract

Aqueous zinc-ion batteries show promise for sustainable energy storage but face practical challenges due to sluggish Zn2+ diffusion and irreversible vanadium dissolution in cathode materials. This study proposes an in situ chemical bonding strategy to anchor nitrogen-doped carbon quantum dots (NCQDs) onto V2O5 nanoparticles, forming heterostructured units with built-in electric fields. These units further self-assemble into spherical assemblies (V2O5/NCQDs), which are embedded within a porous graphene aerogel (GA) matrix to construct a V2O5/NCQDs@GA composite cathode with a hierarchical confinement framework. The discrete arrangement of V2O5/NCQDs heterostructured units forms multi-point conductive network and open ion channels, reducing charge transfer resistance and enhancing Zn2+ diffusion. The spatial confinement and concentration gradient effects of GA synergistically suppress vanadium dissolution and mitigate solvent corrosion, enhancing the structural stability of the electrode. Consequently, the V2O5/NCQDs@GA electrode shows excellent rate capability (309 mAh g−1 at 3.0 A g−1) and cycling stability (retaining 268 mAh g−1 after 1000 cycles).