Constructing Stable Anion-Tuned Electrode/Electrolyte Interphase on High-Voltage Na 3 V 2 (PO 4 ) 2 F 3 Cathode for Thermally-Modulated Fast-Charging Batteries.

Constructing stable electrode/electrolyte interphase with fast interfacial kinetics is vital for fast-charging batteries. Herein, we investigate the interphase that forms between a high-voltage Na ₃ V ₂ (PO ₄ ) ₂ F ₃ cathode and the electrolytes consisting of 3.0, 1.0, or 0.3 M NaClO ₄ in an organic carbonate solvent (47.5 : 47.5 : 5 mixture of EC: PC: FEC) during charging up to 4.5 V at 55 °C. It is found that a higher anion/solvent ratio in electrolyte solvation structure induces anion-dominated interphase containing more inorganic species and more anion derivatives (C _x ClO _y ), which leads to a larger interfacial Na ⁺ transport resistance and more unfavorable gas evolution. In comparison, a low anion/solvent ratio derives stable anion-tuned interphase that enables better interfacial kinetics and cycle ability. Importantly, the performance of a failed cathode is restored by triggering the decomposition of C _x ClO _y species. This work elucidates the role of tuning interphase in fast-charging batteries.
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