Ultra-Long Cycle Life Aqueous Zinc-Ion Battery Optimized by V<sub>2</sub>O<sub>5</sub>@PDA Carbon Regulation Strategy

Aqueous zinc-ion batteries (AZIBs), with the merits of low cost and inherent safety, emerge as promising green energy storage devices. Vanadium pentoxide (V2O5) as a classic AZIB cathode demonstrates superior redox activity and high capacity yet suffers from dual limitations of poor intrinsic conductivity and structural collapse caused by vanadium dissolution during charge/discharge cycles. To address these issues, we propose a surface modification strategy through hydrothermal polymerization of dopamine hydrochloride (PDA) with V2O5 followed by controlled atmosphere annealing, constructing carbon-coated V2O5@PDA spheres. The PDA-derived N-doped carbon coating orchestrates three synergistic effects: (1) Compensating low intrinsic conductivity of V2O5 by forming electron-conductive networks with enhanced charge transfer capability. (2) Engineering spherical architectures with enlarged specific surface area to expose abundant Zn2+ storage sites, while creating ion diffusion pathways that reduce ionic transport resistance within V2O5 matrix (activation energy: 0.67 eV vs. 1.12 eV pristine), and (3) Establishing conformal carbon encapsulation (thickness: 8.5 nm) to mechanically stabilize the structure against dissolution-induced collapse. The optimized composite delivers a high reversible capacity of 410.47 mAh g−1 at 0.1 A g−1 and sustains 62.18% capacity retention after 1000 cycles at 1 A g−1, validating the effectiveness of this surface engineering approach. Mechanistic analysis confirms the carbon coating acts as a dual-functional interface that concurrently enhances electronic connectivity and dissolution resistance, providing a materials design blueprint for high-durability AZIBs cathodes.