Temperature‐Driven Solvation Sheath Reconfiguration Dictates Interphase Chemistry in Lithium‐Ion Battery Electrolytes

Abstract The solvation structure has a significant impact on the composition and structure of the electrode‐electrolyte interphases (EEIs). EEIs rich in inorganic components are generally considered more favorable for enhancing electrochemical performance. However, a clear understanding is still lacking regarding whether a higher inorganic content is always beneficial, and whether the composition requirements for the solid electrolyte interphase (SEI) and the cathode electrolyte interphase (CEI) are consistent. To deeply understand the temperature impact on EEIs, the temperature‐driven solvation dynamics and interfacial chemistry of three homologous electrolytes for lithium‐ion batteries (LIBs): low‐temperature (LiPF 6 − FEC/EA), room‐temperature (LiPF 6 ‐FEC/EMC), and high‐temperature (LiPF 6 − FEC/TEGDME) formulations are systematically investigated. Molecular dynamics simulations and spectroscopic analyses reveal distinct solvation behaviors: elevated temperatures weaken Li⁺‐solvent interactions while strengthening Li⁺‐anion coordination in low‐temperature electrolytes, whereas the opposite trend occurs in high‐temperature systems. Temperature‐dependent interfacial chemistry shows that cluster decomposition dominates LiF‐rich inorganic interphases at extreme temperatures, while solvent decomposition governs organic–inorganic interphases at low temperatures. Electrochemical testing demonstrates that organic–inorganic cathode electrolyte interphases combined with LiF‐rich solid electrolyte interphases achieve superior cycling stability. These findings provide foundational insights into solvation‐interphase correlations and establish design principles for electrolytes tailored to wide‐temperature LIBs.