Dilute Electrolyte with Vehicular Aggregates for Stable High‐Energy Lithium‐Metal Batteries

Abstract Electrolyte design is critical for high‐energy lithium‐metal batteries (LMBs) because it dictates the aggressive Li–electrolyte interphase that governs cycling stability and Coulombic efficiency (CE). However, traditional high‐ or locally high‐concentration electrolytes, which achieve good Li‐metal compatibility by the formation of anion‒solvent‒Li + aggregates (AGG), typically suffer from poor ionic conductivity (e.g., ≈1 mS cm −1 ). Therefore, achieving both high ionic conductivity and AGG‐dominated solvation structure under dilute conditions still remains a challenge. Herein, a novel dilute electrolyte with vehicular aggregates (DVA) mechanism is proposed by employing pyrrolidine‐1‐sulfonyl fluoride (PSF) solvent with optimal steric hindrance effect. Based on this DVA electrolyte, the uniquely AGG‐dominated solvation structure under dilute conditions achieve high ionic conductivity (4.9 mS cm −1 ) featuring its vehicular ion‐transport mechanism. It exhibits good Li‐metal compatibility with high stripping‐plating CE of ≈99.5% with inorganic (LiF, Li 2 O)‐rich robust solid‒electrolyte interphase. Furthermore, the electrolyte effectively suppresses the stress‐corrosion cracking, transition‐metal dissolution, gas evolution, and detrimental surface degradation on the cathode side, thus enabling 4.6‐V‐class LMBs with ultra‐high‐Ni cathodes to deliver a high discharge capacity of 228.4 mAh g −1 , excellent rate capability up to 2C, and 87% capacity retention after 150 cycles. This work offers a promising approach for designing advanced electrolytes for high‐energy LMBs.