Constructing metal alloy protective layers for ultra-long lifespan and high cumulative areal capacity of Zn anodes

Aqueous zinc-ion batteries (AZIBs), with their high theoretical capacity and high safety, and low cost, have stood out among aqueous battery systems. However, Zn dendrite growth in AZIBs limits cycle durability, whereas side reactions degrade stability of anode-electrolyte interfaces, collectively reducing the overall utilization of Zn anodes. This study constructed an artificial protective layer of ZnP/NaP alloy (Z/N-P@Zn) on Zn foil to inhibit side reactions and optimize Zn 2+ deposition behavior, thus suppressing dendrite growth. Density functional theory (DFT) calculations and electrochemical test results reveal that the Z/N-P@Zn anode reduces the activation energy during Zn 2+ desolvation, thereby decreasing energy consumption, improving charge transfer kinetics, and enhancing interfacial ion transport efficiency. Additionally, compared to the bare Zn anode, the more negative hydrogen evolution potential and lower corrosion current density indicate that the Z/N-P protective layer can suppress hydrogen evolution and corrosion reactions. Long-term cycling tests show that the Z/N-P@Zn||Z/N-P@Zn symmetric cell achieves an ultra-long lifespan of 6000 h at a current density of 5 mA cm -2 , with a cumulative areal capacity as high as 15,000 mAh cm -2 . This study provides a simple solution to the lifespan limitations of the Zn anode, offering a new pathway for designing long-lived, high-safety, and low-cost AZIBs.