Analysis of the behavior of Zn atoms with a Pb additive on the surface during Zn electrodeposition

Zn has attracted considerable attention as an effective anode material in post-Li secondary batteries for large-scale, next-generation energy storage. The use of metal additives such as Pb is effective in suppressing undesirable morphological changes in the electrode during charging. More efficient additives can be obtained by investigating the behavior of deposited Zn in the presence of Pb at the atomic level. This study investigates the morphological and structural characteristics of Zn electrodeposition with the addition of Pb. Galvanostatic electrodeposition indicates that distinctive pillar-like Zn grows in the presence of Pb, which is oriented to (0001) in the hexagonal close-packed (hcp) structure, with its side wall oriented toward the hcp-(0–110) structure. The electrodeposited Zn is covered by a top layer of Pb(111). Density functional theory calculations confirm this layer structure by showing that the deposited Zn atoms can penetrate the Pb top layer to reach the Zn underlayer as a surfactant. This feature allows pillars to grow continuously. Understanding the behavior of such deposited atoms also provides insights into the effects and working mechanisms of additives in general.