Cu-doped ZnO nanoarray trap enabling uniform Zn deposition for high-performance Zn-ion batteries

The convergence of active Zn metal anodes and water molecules in aqueous zinc ion batteries (ZIBs) triggers uncontrolled dendrite growth and side reactions, thereby limiting their practical applications. Due to these issues, we fabricated an in-situ protective interlayer featuring a kinetically zincophilic Cu-doped ZnO nanoarray trap by reinventing the inherent oxide layer on the Zn anode. This spontaneous transformation is driven by trace Cu 2+ electrolyte engineering, and the Cu-doped interface easily forms the uniform ZnO nanoarray. This three-dimensional Cu-doped ZnO nanoarray structure functions as an artificial trap, capturing Zn 2+ and anchoring the Zn 2+ deposition behavior along the trap's edges. Consequently, Zn 2+ deposition aligns parallel to the initial Zn anode surface. Both experimental and theoretical analyses confirm that the Cu-doped ZnO nanoarray trap layer possesses a strong adsorption affinity toward the Zn anode surface, enabling tight interfacial bonding with the Zn anode. This unique structure efficiently isolates the Zn anode from active water molecules, thereby suppressing side reactions. These features synergistically reduce the interfacial impedance and facilitate the fast Zn 2+ transfer. Therefore, the Cu-doped ZnO layer enables long-term stability (1014 h) in a symmetric cell. The full cells, matched with VO 2 cathode material, exhibit an extraordinary performance of over 1100 cycles with a high discharge capacity of 205 mAh g −1 at 2 A g −1 . This strategy of constructing a unique ZnO nanoarray trap structure for the Zn anode may fully leverage the passivation layer and achieve large-scale practical application of ZIBs.