Ring Strain Engineering of Cyclic Ethers for High‐Performance Sodium Metal Batteries

ABSTRACT 1,3‐dioxolane is a promising solvent for low‐temperature batteries owing to its low freezing point and low viscosity. However, its tendency toward ring‐opening polymerization leads to reduced ionic conductivity and deteriorated electrochemical stability. Here, we establish an electronic–geometric coupling design principle to regulate solvent stability in weak–weak electrolyte systems for sodium metal batteries. A dual‐descriptor framework combining ring strain energy (RSE) and a sterically corrected electrostatic descriptor, defined by the lowest negative electrostatic potential normalized by molecular volume (ESP min /Volume), is introduced to guide cyclic ether solvent design. Following this principle, 2,4‐dimethyl‐1,3‐dioxolane is identified with reduced RSE and moderate ESP min /Volume, enabling enhanced resistance to polymerization and improved Na‐compatibility/ion transport. Molecular dynamics simulations and density functional theory calculations reveal that, the electrolyte forms an aggregate‐dominated solvation structure with a high lowest unoccupied molecular orbital level, promoting the formation of a thin, uniform, and inorganic‐rich solid electrolyte interphase. Consequently, the electrolyte delivers accelerated interfacial kinetics and stable operation across a wide temperature range. Na||Na symmetric cells cycle stably for 1800 h at room temperature, while Na||Na 3 V 2 (PO 4 ) 3 full cells with high cathode loading (20 mg cm −2 ) operate for over 200 cycles at 25 °C and more than 900 cycles at −40° C.