Bismuth-guided cavity confinement breaks the stability-utilization trade-off in zinc powder anodes

The practical application of aqueous zinc-ion batteries (AZIBs) is severely hindered by the poor reversibility of the Zn anode, which stems from a self-amplifying cycle involving dendrite growth, interfacial side reactions, and electrically isolated "dead Zn" formation. Here, we report a spray-assembled three-dimensional copper mesh-supported particulate Zn anode, in which Zn particles are encapsulated by an inner bismuth interlayer and an outer carbon confinement shell (3D-C/Bi@Zn-p). Unlike conventional surface stabilization strategies, this surface-engineered architecture enables a unique interface-guided, cavity-confined inward deposition mechanism. During stripping, Zn is selectively extracted from the particle core, leaving behind a robust bismuth-carbon composite shell embedded with isolated internal cavities. In the subsequent plating step, the passivated carbon outer layer effectively suppresses parasitic reactions and prevents Zn nucleation on the external surface, while the inner bismuth layer provides a highly zincophilic interface that kinetically directs Zn²⁺ to undergo plating exclusively in the cavity interior. Consequently, Zn plating is spatially confined within isolated cavities, effectively suppressing outward dendrite propagation and eliminating the risk of short circuits. Benefiting from this cavity-confined inward deposition behavior, the 3D-C/Bi@Zn-p anode delivers a coulombic efficiency approaching 100% and enables record-high stable cycling for over 10 000 h at 1 mA cm^-2 under high zinc utilization of 10.8%. Notably, stable Zn plating/stripping can still be maintained at an ultrahigh Zn utilization of 108%, far beyond the <1% Zn utilization commonly employed in most laboratory-scale studies. Furthermore, when paired with an oxygen-deficient V₂O_5-x cathode, the full cell delivers 211.6 Wh kg^-1 and 81.2% capacity retention after 1000 cycles under lean-anode conditions (N/P = 2.4, ∼30.3% Zn utilization), outperforming most reported AZIBs. This interface-guided cavity-confined inward deposition strategy establishes a new spatial confinement paradigm for reversible metal anodes.