Ion–Dipole Interactions Modulated Anion-Reinforced Solvation Chemistry for Advanced Wide-Temperature Sodium-Ion Full Batteries

Wide-temperature sodium-ion batteries (SIBs) are considered promising candidates for large-scale energy storage systems under extreme temperature conditions. However, SIBs generally suffer from an unstable electrode-electrolyte interface (EEI) at high temperature and sluggish interfacial kinetics at low temperature, resulting in poor temperature tolerance with fast capacity degradation. Herein, a weakly coordinated carboxylate ester cosolvent, methyl butyrate, is employed to modulate the ion-dipole interactions in fluorine-free ester-based electrolyte for the anion-reinforced solvation chemistry. The unique solvent chemistry enables the construction of stable anion-derived inorganic-rich EEI on both cathode and anode surfaces while simultaneously reducing the desolvation energy barrier, thereby significantly enhancing the interfacial stability and kinetics. Therefore, the Prussian blue||hard carbon (PB||HC) full cell demonstrates a stable operation at a wide temperature range from -20 to 100 °C. Noticeably, the PB||HC 18650 cylindrical cell delivers a superior capacity retention of 91.41% after 230 cycles at an elevated temperature of 55 °C. This work provides valuable guidance for designing fluorine-free ester-based electrolytes through rational modulation of ion-dipole interactions, paving a promising pathway for wide-temperature sodium-ion full batteries.