Rational Design of Ether‐Based Localized Weak Solvation Liquid Electrolyte for Practical Lithium Metal Batteries

Abstract Although localized high concentration electrolytes (LHCEs) exhibit compatibility with state‐of‐the‐art high‐voltage cathodes and lithium metal anodes, their practical implementation is hindered by the excessive volume fraction of fluorinated diluents and suboptimal ionic conductivity. Herein, a localized weak solvation strategy is proposed to preserve electrode interfacial stability while reducing fluorinated diluent content. Specifically, ethylene glycol dibutyl ether (DBE) is identified as a weakly coordinating solvent due to its steric hindrance effect, which preferentially facilitates contact ion pair formation at reduced salt concentrations. Furthermore, the non‐coordinating (trifluoromethyl) cyclohexane (TFMH) diluent synergistically enhances anion‐cation interactions while maintaining residual free solvent molecules as ion transport sites. Benefiting from this rational electrolyte design, the 9 mg cm − 2 NCM811‐Li cell demonstrates exceptional cycling stability under 4.4 V cutoff voltage, achieving 91.3% capacity retention and 99.9% average Coulombic efficiency over 400 cycles. Remarkably, even under practical conditions employing a high cathode loading (21 mg cm − 2 ) and ultrathin Li metal anode (50 µm), the NCM811‐Li full cell maintains stable operation for 160 cycles.