Mn ²⁺ Ion‐Mediated Zn Dendrite Suppression and Reversible Stripping in Aqueous Zn‐Ion Batteries as Revealed by In Situ Liquid‐Cell TEM

Achieving uniform Zn deposition and its reversible dissolution at the anode remains a major challenge in aqueous zinc‐ion batteries (AZIBs), where dendrite growth and interfacial instability limit the cycling life. Herein, we employ in situ electrochemical liquid‐phase transmission electron microscopy (EC‐LPTEM) to mimic a battery operation and directly visualize Zn electrodeposition in the presence of MnSO 4 in an aqueous ZnSO 4 electrolyte. Real‐time observations reveal that Mn 2+ ions regulate interfacial nucleation, suppress dendritic elongation, and promote uniform plating, while facilitating nearly complete Zn dissolution during stripping. Post‐deposition analyses using transmission electron microscopy (TEM), selected area electron diffraction (SAED), and scanning transmission electron microscopy–energy dispersive X‐ray spectroscopy (STEM‐EDS) show that Mn 2+ ions are incorporated into chemically labile Zn–Mn–O–S interfacial deposits. Ex situ electrochemical measurements confirm that Mn 2+ ions improve Zn anode stability and extend cycling performance. These findings provide direct nanoscale insights into additive‐regulated Zn deposition and highlight Mn 2+ ion‐mediated interfacial modulation as an effective strategy for controlling Zn deposit morphology and enhancing AZIB durability.