Synergistic V5S8/CoS Nanoparticles-Embedded Carbon Nanofiber as Binder-Free Flexible Anode for Sodium-Ion Batteries

Abstract The development of advanced electrode materials for sodium-ion batteries (SIBs) is crucial for the progression of energy storage technologies. In this study, we successfully fabricated V 5 S 8 /CoS nanoparticles confined within self-supported carbon nanofibers (CNFs) using a facile electrospinning method followed by a sulfidation process. Extensive characterization of the resulting V 5 S 8 /CoS-CNFs revealed their unique structural attributes, featuring a one-dimensional nanofiber morphology with enhanced Na + transport pathways. These V 5 S 8 /CoS-CNFs exhibited a remarkable reversible capacity of 201 mAh g −1 even at a high current density of 5 A g −1 , along with a stable cycling performance of 165 mA h g −1 after 300 cycles at 2 A g −1 . The incorporation of both V 5 S 8 and CoS within the nanofiber structure substantially enhanced the pseudocapacitance effect, thereby improving sodium storage capabilities. The exceptional electrochemical properties of the binder-free V 5 S 8 /CoS-CNFs anode can be attributed to its heterogeneous composition embedded within CNFs. This composition effectively boosts the rate of sodium ion diffusion by generating a built-in electric field (BEF) at the V 5 S 8 and CoS interface, alleviating volume stress during charge-discharge processes and enhancing overall conductivity. Our findings underscore the potential of V 5 S 8 /CoS-CNFs as high-performance anode materials for SIBs, offering valuable insights into the design and development of advanced electrode materials for future energy storage applications.