Hierarchical V 3 S 4 /C nanofibers with fast kinetics for superior alkali metal batteries

Owing to the numerous benefits, including low cost and great theoretical capacity, V 3 S 4 has been a research hotspot for Li + /Na + /K + storage. Nonetheless, the V 3 S 4 electrode with long cycling stability and high specific capacities continues to pose significant challenges. In this work, vacuum vulcanization is combined with electrospinning to synthesize V 3 S 4 /C composite nanofibers (V 3 S 4 @CNF). The study finds out that many nanosheets attach to the surface of the nanofibers following vulcanization, and the surface becomes rougher. This allows V 3 S 4 @CNF to create exterior defects, which improves Li + /Na + /K + transport and increased electrochemical active sites. The result shows that the V 3 S 4 @CNF electrode can retain the capacities of 291.3 mAh·g −1 (at the 1000th cycle) and 241.9 mAh·g −1 (at the 2400th cycle) at 5 A·g −1 for Li + /Na + storage, respectively, indicating exceptional cyclic stability. A great potential in practical application is also exhibited, where the full cell based on Na 3 V 2 (PO 4 ) 3 /C(NVP/C)//V 3 S 4 @CNF can maintain a reversible capacity of 114 mAh·g −1 after 200 cycles at 1 A·g −1 . Furthermore, the V 3 S 4 @CNF electrode has a discharge specific capacity of 270.7 mAh·g −1 at the 600th cycle at 1 A·g −1 for potassium‐ion batteries. This research can serve as a solid foundation for the ultimate development of alternative sulfide‐treated electrode materials for high‐performance Li + /Na + /K + storage.