Ultra‐Stable Zinc Metal Batteries Enabled by Adsorption‐Desorption Equilibrium of Zinc Ions at the Additive‐Mediated Interfacial Layers

Abstract Structural‐tunable organic electrolyte additives demonstrate critical significance in enhancing zinc anode stability and promoting practical applications of aqueous zinc‐ion batteries (AZIBs). However, while numerous additives have been reported to mitigate parasitic reactions in zinc anodes effectively, the fundamental understanding concerning organic additive molecular structures in modulating zinc‐ion interfacial chemistry remains insufficiently understood. In this work, a comparative investigation of two adsorptive organic additives with similar structures elucidates the critical role of adsorption‐desorption equilibrium in regulating zinc‐ion interfacial transport kinetics. Piperidine‐2‐carboxylic acid (PPCA) exhibits superior capability in accelerating zinc‐ion transport across the anode/electrolyte interface compared to pyridine‐2‐carboxylic acid (PDCA), attributable to its optimized adsorption configuration and enhanced charge redistribution effects. Besides, the PPCA layer with a poor H ₂ O environment creates a uniform zinc ion flux, which decreases concentration polarization and inhibits parasitic reactions. Consequently, the Zn||Zn symmetric cells with PPCA additive enable an exceptional cycle life over 4300 h at 1 mA cm ⁻² and 1 mAh cm ⁻² . A high coulombic efficiency of 99.8% after 1500 cycles is achieved for Zn||Cu cells with PPCA additive, which is significantly better than the cells with PDCA additive. This work highlights the structural regulation of functional electrolyte additives toward high‐performance AZIBs.