Interfacial Coordination-Gradient Regulation of Zn Deposition for Ultrastable Alkaline Zn-Ni Batteries

Achieving long-term stable zinc anodes at high currents and capacities remains a great challenge for practical aqueous alkaline zinc-nickel batteries. Herein, we construct a coordination-gradient interphase by integrating a carboxyl-functional carbon shell with spatially graded Zn 2 + binding affinity. The resulting interphase exhibits a stratified distribution of oxygen-containing groups, establishing a directional pathway for Zn 2 + transport. This gradient structure suppresses hydrogen evolution and passivation by preserving ZnO lattice integrity, while simultaneously regulating the electric field and Zn 2 + flux to promote uniform deposition and inhibit dendrite growth under demanding operating conditions. As a result, the coordinated-gradient Zn anode enables stable cycling for over 900 h in a Zn||Zn symmetric cell at 5 mA cm − 2 with negligible polarization, which outperforms most previously reported modified Zn anodes in alkaline electrolytes. The proposed gradient interphase design is scalable, and a high-performance Zn-Ni full battery with high mass loading (50 mg cm − 2 ) is also demonstrated, delivering an areal capacity of 17 mAh cm − 2 at 80 mA cm − 2 and retaining nearly full capacity over 9000 cycles with a Coulombic efficiency of 92%.