Synergistic Anion‐Reinforced Solvation Chemistry and Cationic Electrostatic Shielding for Fast‐Charging Sodium‐Ion Full Batteries Over a Wide Temperature Range

ABSTRACT Sodium‐ion batteries (SIBs) capable of stable operation under fast‐charging conditions across a wide temperature range are of great significance for the efficient utilization of intermittent renewable clean energy. Herein, a multifunctional electrolyte additive containing tetrabutylammonium (TBA + ) cation and perchlorate (ClO 4 − ) anion is employed to construct an environmentally friendly fluorine‐free electrolyte system, significantly enhancing the temperature tolerance and fast‐charging performance of SIBs. Specifically, the TBA + cations, due to their low reduction potential, induce an electrostatic shielding effect that guides the uniform distribution of Na + flux on the electrode surface. Meanwhile, the introduced ClO 4 − anions facilitate the formation of the anion‐reinforced solvation structure. This structure effectively reduces the desolvation energy barrier of Na + and promotes the formation of a stable electrode‐electrolyte interface with high ionic conductivity. This synergistic mechanism effectively suppresses Na plating during fast charging and mitigates continuous electrolyte decomposition and transition metal dissolution. Consequently, the assembled Prussian blue||hard carbon (PB||HC) full cell demonstrates excellent fast‐charging performance across a wide temperature range (10–100°C). More importantly, the PB||HC 18650 cylindrical cell exhibits a superior cycling stability and outstanding rate performance at an elevated temperature of 55°C, demonstrating the great potential of this electrolyte system for practical applications.