Achieving Stable Zinc Anodes by In Situ Constructing an Artificial Interface Layer with ZnO/Cu Gradient Zinc Affinity

Zinc metal is one of the most promising anode materials for aqueous batteries. However, nonuniform deposition of zinc metal anodes and hydrogen evolution reactions (HER) severely affect the stability of aqueous zinc–ion batteries. Herein, a simple redox reaction between zinc metal and graphene oxide and a subsequent one-step replacement reaction were utilized to in situ fabricate rod-shaped zinc oxide, reduced graphene oxide (rGO), and Cu nanoparticles on the zinc anode surface. This ingenious design constructs an artificial gradient zinc-affinity interface layer (ZnO–rGO–Cu), which regulates the longitudinal electric field distribution, enabling Zn2+ to deposit uniformly along the gradient from bottom to top, thereby suppressing the dendrites growth. Besides, Cu nanoparticles and rGO partially isolate the zinc from the electrolyte to inhibit the unwanted HER. Moreover, these components reduce the interface contact angle with aqueous electrolytes, enhancing electrolyte affinity and electrochemical activity. Consequently, the Zn–rGO–Cu symmetric cells cycle stably for 1000 h at 1 mA cm–2, and the half-cells achieve 1500 stable cycles at 2 mA cm–2 with a high Coulombic efficiency of 99%. Furthermore, full cells paired with manganese-based and vanadium-based cathodes stably cycle 900 times at 0.5 A g–1 and 600 times at 2 A g–1, respectively. This study thus provides insights into rationally designing multifunctional interphase layers for high-performance zinc–ion batteries.