Fine‐Tuning Li‐Ion Solvation Structure by Enhanced Solvent‐Diluent Interactions for Long‐Cycling Lithium Metal Batteries

Abstract Achieving durable lithium (Li) metal anodes in liquid electrolytes remains challenging, primarily due to the instability of the formed solid‐electrolyte interphases (SEIs). Modulating the Li‐ion solvation structures is pivotal in forming a stable SEI for stabilizing Li metal anodes. Here a strategy is developed to fine‐tune the Li‐ion solvation structures through enhanced dipole–dipole interactions between the Li‐ion‐coordinated solvent and the non‐Li‐ion‐coordinating diluent, for creating a stable SEI in the developed binary salt electrolyte. The enhanced dipole–dipole interactions weaken the coordination between Li‐ions and the solvents while strengthening the interaction between Li‐ions and dual anions, thereby facilitating the Li‐ion transport and a robust anion‐derived SEI with a distinct bilayer structure. Consequently, the developed electrolyte exhibited exceptional electrochemical performance in high energy‐density Li||LiNi0.8Mn0.1Co0.1O2 (NMC811) cells, with long calendar life, stable cyclability at 1 C, and reliable operation between 25 and −20 °C, and it also demonstrat remarkable cycling stability for a Li||NMC811 pouch cell with projected energy density of 402 Wh kg−1, maintaining 80% capacity retention over 606 cycles under practical conditions.