Multifunctional Dual‐Metal‐Salt Derived Ternary Eutectic Electrolyte for Highly Reversible Zinc Ion Battery

Abstract Deep eutectic electrolytes offer opportunities for tailoring solvation structure and interface chemistry in advanced batteries, but developing deep eutectic electrolytes for high‐performance zinc ion batteries (ZIBs) remains a challenge. Herein, multifunctional dual‐metal‐salt derived ternary eutectic electrolytes (DMEEs) are designed via a supporting salt strategy for dendrite‐free and long‐lifespan ZIBs. DMEEs are constructed by zinc trifluoromethanesulfonate (Zn(OTF) 2 ), supporting salt of lithium bis(trifluoromethanesulfonyl)imide, and neutral ligand of N‐methylacetamide. Noticeably, supporting salt with weak lattice energy not only induces the reconstruction of intermolecular interactions to form ion pairs and ion aggregates but also tailors the Zn 2+ solvation structure and solid electrolyte interface (SEI). The developed DMEEs possess a dual‐anion‐rich Zn 2+ solvation shell and induce an inorganic‐rich hybrid SEI, which effectively suppresses side reactions and obtains a dendrite‐free Zn anode with high reversibility. Remarkably, Zn//Zn cells demonstrate cycling stability for over 3000 h, and Zn//PANI full cells deliver no significant capacity decay after 5000 cycles at a high current density of 5 A g −1 . This work opens a new avenue to design advanced deep eutectic electrolytes, and the deep understanding of solvation structure and SEI offers guidelines for developing high‐performance batteries.