Highly Reversible Zinc Anode Enabled by a Thiourea-Derived Protective Layer for Alkaline Zinc Batteries

Zinc-based batteries hold great promise as next-generation energy storage systems due to their low cost, intrinsic safety, and high energy density. However, their long-term stability and efficiency are severely limited by the irreversible zinc plating/stripping reactions that lead to dendrite growth and parasitic side reactions, such as ZnO formation and hydrogen evolution. Here, we present a simple strategy to stabilize the zinc anode by growing a conjoint zinc sulfide (ZnS) and polymeric carbon nitride (CN) binder-free protective layer directly on the Zn surface. Structural and electrochemical analyses demonstrate that this hybrid interphase effectively regulates Zn²⁺ nucleation, suppresses dendrite formation, and minimizes parasitic reactions, thereby enabling highly reversible zinc cycling with excellent long-term stability. The optimized Zn anode exhibits a low voltage hysteresis of 170 mV at a high areal capacity of 30 mAh cm^-2 (at 30 mA cm^-2) for over 170 h, achieving more than three times the cycle life of bare zinc. When integrated into a rechargeable zinc-peroxide battery, it delivers state-of-the-art performance, maintaining stable operation for 1100 h at 9 mAh cm^-2.