Synergistic Solvation Structure Modulation in Ether-Based Electrolytes for High-Performance Lithium Metal Batteries

Ether-based electrolytes are promising candidates for lithium metal batteries (LMBs) due to their high ionic conductivity and favorable compatibility with lithium metal anodes. However, their limited oxidative stability restricts practical integration with high-voltage cathodes, and current strategies to enhance oxidative stability often compromise their inherent advantages in conductivity and Li-metal compatibility. Herein, we report an ether-based localized medium-concentration electrolyte designed via the synergistic effect of a highly associated salt additive and a nonsolvating diluent. This strategy optimized the Li+ solvation structure through controlled anion coordination while preserving fast charge-transfer kinetics. The optimized electrolyte achieved high ionic conductivity (10.42 mS cm–1 at room temperature), enabled uniform and dense lithium deposition, and promoted the formation of a thin and uniform cathode–electrolyte interphase (CEI). Consequently, 4.4 V Li||LiNi0.6Mn0.2Co0.2O2(NMC622) cells with a high cathode loading (9.6 mg cm–2) exhibited excellent rate capability and cycling stability. These findings highlight the promise of balance-oriented solvation regulation via additive–diluent cooperation for high-performance ether electrolytes in next-generation LMBs.