Mediating Role of Electrode Process Kinetics in Stabilizing Zn Anodes Through Electrolyte Additives

Abstract Electrolyte additives are commonly employed to regulate solvation structures and interfacial chemistry, suppressing hydrogen evolution reaction (HER) and uneven deposition in aqueous Zn batteries. However, the impact of additive‐induced evolutions in electrode process kinetics on Zn anode stability has long been overlooked, limiting further gains in stability. This work combines in situ spectroscopy, electrochemical quartz crystal microbalance measurements, and theoretical calculations to reveal how aldehyde‐functionalized additives enhance anode stability by regulating electrode kinetics. First, incorporating aldehyde groups disrupts the hydrogen‐bond network of water and impedes Zn 2+ diffusion, thereby suppressing HER while causing non‐uniform deposition, respectively. Second, charge transfer for Zn 2+ reduction and HER are hindered, helping to achieve uniform deposition and inhibit HER. Third, introducing aldehyde groups preserves instantaneous nucleation and increases nucleus density, enhancing the deposit compactness. Fourth, although the growth orientation remains unchanged, adatom self‐diffusion is accelerated, promoting uniform deposition. An optimal single aldehyde moiety achieves uniform Zn deposition and efficient HER suppression, delivering a long cycle life and high Coulombic efficiency. Excessive aldehyde content causes uneven plating and reduced stability. This work refines the mechanistic understanding of how functional groups in organic additives affect Zn anode stability, thereby guiding the rational design of optimal additive formulations.