Controllable Solid Electrolyte Interphase by Ionic Environment Regulation for Stable Zn‐Ion Battery

Abstract Artificial solid electrolyte interphase in organic solutions is effective and facile for long‐cycling aqueous zinc ion batteries. However, the specific effects on different ionic environments have not been thoroughly investigated. Herein, pyromellitic acid (PA) are employed as organic ligand to coordinate with Zn 2+ under various ionic environments. The connection between the ionic environment and reaction spontaneity is analyzed to provide insights into the reasons behind the effectiveness of the SEI layer and to characterize its protective impact on the zinc anode. Notably, the PA solution (pH4) lacking OH − contributes to the formation of a dense and ultrathin SEI with Zn‐PA coordination, preventing direct contact between the anode and electrolyte. Moreover, the presence of organic functional groups facilitates a uniform flux of Zn 2+ . These advantages enable stable cycling of the PA4‐Zn symmetric cell at a current density of 3 mA cm −2 for over 3500 h. The PA4‐Zn//MVO full cell demonstrates excellent electrochemical reversibility. Investigating the influence of the ionic environment on SEI generation informs the development of novel SEI strategies.