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 Nb(2)O(5 )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/Nb2O5 fibers, which were transformed into porous ceramic Nb2O5 nanofibers via calcination. Thermogravimetric studies defined that calcination at 600 degrees 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 m(2)/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 Nb2O(5) nanofibers in the carbon cathode inhibits the shuttle effect through polysulphide confinement, which originates from porosity and chemical trapping.