Ternary Anion‐Engineered Solvation Sheaths in Lightweight Electrolyte Enable Dual‐Interface Stability for Lithium Metal Batteries

Abstract

Abstract Ether‐based electrolytes promise superior interfacial stability with lithium metal under high salt concentration, while poor oxidative stability limits the high‐voltage operation. Extending the intrinsic electrochemical window and reducing the salt concentration to design high‐voltage lithium metal batteries is challenging and urgent. Herein, lightweight electrolytes based on intermolecular interactions regulated by ternary anion chemistry are proposed. An anion‐enriched solvation structure is achieved at a standard salt concentration (1 m ) via enhanced ion‐dipole interactions, generating an inorganic‐rich electrode‐electrolyte interphase and enabling facile lithium plating/stripping kinetics. This results in lithium metal exhibiting an average Coulombic efficiency of 97.9% and a prolonged cycling lifespan (1000 h) at 2 mA cm⁻ 2 . The hydrogen bond‐like interactions between NO 3 − /TFSI − and tetrahydrofuran, coupled with the preferential decomposition of DFOB − on the Ni‐rich cathode, boosts the electrolyte oxidative stability and mitigates the structural degradation of the cathode. Consequently, the Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells demonstrate improved cycling stability (retaining 75% capacity after 300 cycles) and superior rate capability (153.6 mAh g⁻ 1 at 5C) at high cathode loading. This work supplies a molecular‐level design strategy for low‐concentration electrolytes tailored for high‐voltage lithium metal batteries, offering a promising pathway toward practical high‐energy‐density storage systems.