Porous Nb₂O₅ nanofibers prepared via reactive needle-less electrospinning for application in lithium–sulfur batteries

This contribution describes the preparation, coupled with detailed characterization, of Nb₂O₅ nanofibers and their application in lithium–sulfur batteries for the improvement of electrochemical performance. The utilization of reactive needle-less electrospinning allowed us to obtain, in a single step, amorphous pre-ceramic composite PAN/Nb₂O₅fibers, which were transformed into porous ceramic Nb₂O₅ nanofibers via calcination. Thermogravimetric studies defined that calcination at 600 ◦C results in crystalline ceramic fibers without carbon residues. The fibrous morphology and mean diameter (614 ± 100 nm) of the ceramic nanofibers were analyzed via scanning and transmission electron microscopy. A surface area of 7.472 m²/g was determined through nitrogen adsorption measurements, while a combination of X-ray diffraction and Raman spectroscopy was used to show the crystallinity and composition of the fibers after calcination—single T-phase Nb₂O₅ . Its performance in the cathode of lithium–sulfur batteries was defined through electrochemical tests, and the obtained results were compared to a similar blank electrode. The initial discharge capacity of 0.5 C reached a value of 570 mAh·g⁻¹ , while the reversible capacity of 406 mAh·g⁻¹ was retained after 200 cycles, representing a capacity retention of 71.3%. The presence of Nb₂O₅ nanofibers in the carbon cathode inhibits the shuttle effect through polysulphide confinement, which originates from porosity and chemical trapping.