Synergistic Anion-Reinforced Solvation Chemistry and Cationic Electrostatic Shielding for Fast-Charging Sodium-Ion...

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 (ClO₄ ^-) 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 ClO₄ ^- 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.