Defying the Kinetics Limitations of Na ₃ V ₂ (PO ₄ ) ₂ F ₃ Cathode by a Tailored Sol‐Gel Thermal Protocol: Toward Ultra‐Stable Sodium Storage at High Rates and Subzero Temperatures

ABSTRACT Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) is a promising cathode material for sodium‐ion batteries owing to its stable performance, yet its application is hindered by low electronic conductivity and sluggish ion diffusion kinetics. Herein, a temperature‐regulated sol‐gel strategy is developed to tailor the particle size, enhance carbon coating uniformity, and modulate sodium‐site occupancy in NVPF. By optimizing the sol‐gel temperature, it can effectively improve the chelation state of the precursor, reducing particle size and promoting the ordered assembly of primary particles into well‐defined secondary particles, which shortens the Na + transport distance. Simultaneously, the uniform carbon coating improves the electronic conductivity, while the tailored sodium‐site occupancy enhances Na + diffusion kinetics. The optimized NVPF cathode demonstrates a high specific capacity and excellent rate capability (124.5 mAh g −1 at 1C; 103.6 mAh g −1 even at 30C). Additionally, it demonstrates exceptional low‐temperature performance, achieving an initial specific capacity of 100.1 mAh g −1 at 0.1C under −30°C, with a capacity retention of 93.0% after 780 cycles. Furthermore, the full cell shows superior rate capability and cycling stability, reaching 103.0 mAh g −1 at 10C. This work provides a robust strategy for enhancing the electrochemical performance of NVPF and highlights its potential for advanced sodium‐ion battery applications.