Strengthening TMP‐Derived Phosphate SEI via Sn Scaffold and BF 4 − Interphase Chemistry for Ultra‐Stable, High‐Rate Zn Metal Anodes

ABSTRACT While dynamic solid electrolyte interphase (SEI) construction and solvation engineering have transformed aqueous zinc‐ion batteries, translating these approaches to Organic electrolytes (OE) remains a challenging endeavor due to fundamentally different interfacial environments, solvation thermodynamics, and anion decomposition pathways. Despite providing superior thermodynamic stabilization to Zn anode, OE exhibits low ionic conductivity, thereby limiting operational current densities. Herein, we report the first demonstration of Sn(BF 4 ) 2 /H 2 O (SFB) additive integration in a non‐flammable trimethyl phosphate (TMP)‐ethanol (EtOH) (2:1 v/v) OE to architect a gradient SEI interphase on Zn anodes. The multifunctional integration of SFB facilitates the formation of a Sn‐coated Zn surface, a BF 4 1− ‐derived SEI@Zn, and H 2 O molecules as a proton source, collectively contributing to enhanced capacity. This strategic solvent‐salt‐metal synergy enables bi‐layered interfacial engineering within a single electrolyte system, significantly improving the reversibility and stability of the Zn anode. Consequently, SFB enables a robust SEI, achieving exceptional Zn anode durability (7000 h), high‐rate capability (10 mA cm −2 ), and a high Coulombic efficiency (CE) of 99.8%. Full cells with SFB outperform controls in coin and pouch configurations. Given the rarity of additive(s) in OEs, this study offers a new path to boost stability and lifespan of non‐aqueous Zn batteries.