A Temperature‐Adapted Ultraweakly Solvating Electrolyte for Cold‐Resistant Sodium‐Ion Batteries

Abstract

Abstract Sodium‐ion batteries are applied to cold‐resistant energy storage hindered by phase transitions and sluggish Na + migration of traditional carbonate‐based electrolytes at low temperatures. The desolvation of Na + is a crucial step in impeding the transport of Na + , which primarily attributes to the robust solvent coordination of Na + . Herein, a low‐temperature adaptive electrolyte with an ultraweakly coordinated 1,3‐dioxolane (DOL) is designed for constructing anion‐rich solvation structure in a diglyme (G2)‐based electrolyte. The electronegativity of the oxygen atoms of G2 is attenuated by dipole‐dipole interaction between DOL and G2. As the temperature drops, the weakened Na + ‒O (G2) interaction leads to increased anionic coordination and less solvent coordination, facilitating the desolvation of Na + . This anionic‐enhanced solvation structure contributes to the formation of stable solid electrolyte interface at the hard carbon (HC) anode, which accelerates Na + transport and diminishing the voltage polarization at low temperatures. Consequently, the HC anode can retain a high capacity of 203.9 mAh g ‒1 (1 C) at ‒50 °C, and the pouch cell composed of HC||Na 3 V 2 (PO 4 ) 3 at ‒30 °C achieves a capacity retention of 92.43% after 100 cycles at 0.1 C. This strategy guides the design of ultra‐low temperature electrolytes and broadens the range of applications for sodium‐ion batteries.