Current-density-dependent interphase formation and V4+/V5+ activation unlocking low-rate durability of VO2 (B) toward commercializable aqueous zinc-ion batteries.

Aqueous zinc-ion batteries (AZIBs) are promising for large-scale energy storage, but their practical application is limited by rapid capacity fading particularly at low current densities-a phenomenon driven by cathode dissolution and structural degradation. Herein, we report ultrathin single-crystalline VO2 (B) nanobelts that overcome this challenge through a synergistic dual mechanism. The unique nanostructure promotes the in situ formation of a reversible, current-density-dependent Zn x (CF3SO3) y (OH)2x-y ·nH2O interphase that suppresses vanadium dissolution, while progressive activation of the V4+/V5+ redox couple compensates for capacity loss from the V3+/V4+ couple. This enables an exceptional capacity retention of 113.8% after 2000 cycles at 0.5 A g-1, and even under a high mass loading (10.1 mg cm-2), it can still achieve stable cycling for 200 cycles. Critically, post-mortem analyses reveal that the cell performance failure originates from anode degradation, rather than the cathode collapse. By introducing a dimethyl sulfoxide-modified electrolyte to stabilize Zn deposition, we achieve 150 stable cycles under challenging conditions: high mass loading (10.3 mg cm-2), low current density (0.2 A g-1), and a low negative-to-positive electrode capacity ratio (≈2.5). The contribution here demonstrates that engineering ultrathin single-crystalline cathodes, combined with anode stabilization, provides a promising pathway toward commercializable AZIBs.