In situ visualization of interfacial evolution in Cr-modified zinc anodes via atomic force microscopy

Aqueous zinc metal batteries are promising for energy storage, yet their application is constrained by the thermodynamic instability of Zn anodes. A deep understanding of interfacial evolution including initial nucleation and dendrite growth is crucial to guide electrochemical performance optimization, while real-time characterization remains a major technical hurdle. Herein, a homemade Cr-modified zinc foil (Zn@Cr) is designed as the working electrode for in situ electrochemical atomic force microscopy (AFM), enabling real-time visualization of initial nucleation and subsequent plating/stripping morphology evolution from the nano- to micrometer scale. The zincophilic Cr coating promotes uniform nucleation and forms a ZnCr interphase via in situ alloying at the early stage of electrodeposition, which functions as a physical barrier against electrolyte corrosion and preserves structural integrity during cycling. Consequently, Zn@Cr symmetric cells deliver ultralow nucleation overpotential and prolonged cycling stability, completely free of Zn dendrites. This work not only demonstrates an effective alloying-based interfacial strategy for stabilizing zinc anodes but also highlights the capability of in situ AFM in revealing dynamic interfacial evolution.