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

This is the authors' abstract. We don't add key points for this paper.

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.