Revisiting Zn-specific nucleation via a dimensionless factor to quantify interfacial electrochemistry of aqueous batteries.

Zn-based aqueous batteries have attracted widespread research attention, while the lack of nucleation theory for electrochemical interactions at the Zn-water interface constrains efforts to suppress the thermodynamically spontaneous hydrogen evolution reaction and dendrite formation, thereby stalling practical development. Elucidating Zn electrodeposition in aqueous media requires Zn-specific nucleation theory and a descriptor to regulate interfacial electrochemistry. Conventional Li-based spherical nucleation models disregard Zn's crystallography and the interfacial resistance that governs nucleation, thereby focusing on polarization variations. In this work, we reformulate the classical spherical nucleation theory derived by Li for the hexagonal close-packed structure of Zn and establish a dimensionless descriptor (Wf) to quantitatively rationalize interfacial electrochemistry. Wf synthesizes the polarization driving force and interfacial resistance into a stability metric. Higher Wf values facilitate uniform Zn deposition, as evidenced by the literature. Accordingly, we develop a high-Wf electrolyte to inhibit dendrites and side reactions, achieving over 700 h at 100% depth of discharge and 7660 cycles at 10 A g-1 in a Zn||NaV3O8 cell. This work provides a fundamental nucleation theory and a generally applicable quantitative metric for the rational design of Zn-based aqueous batteries.