Synthesis of a Sodium-Ion Cathode Material Na 3 Fe 2 (SO 4 ) 3 F with the Help of Fluorine Element.

The development of cathode materials has always been one of the most crucial areas of research in the field of sodium-ion batteries. Sulfate-based polyanionic materials, known for their high working voltage characteristics, have received widespread attention. In this work, a fluoro-sulfate sodium-ion battery cathode material, Na 3 Fe 2 (SO 4 ) 3 F modified with carbon nanotubes, was developed using a low-temperature solid-state annealing method. This Na 3 Fe 2 (SO 4 ) 3 F cathode exhibits an exceptionally high voltage of 3.77 V, excellent discharge capacity (102 mAh/g at 0.1C), and good rate capability. This material broadens the research directions for cathode materials and holds promise as a foundation for the further development of high-performance sodium-ion batteries.