Electrospun N-doped carbon nanofibers confined Fe1-xS composite as superior anode material for sodium-ion battery

Iron sulfides show great application potential for sodium storage. However, the volume changes and dissolution of polysulfide intermediates severely restrict the lifespan of cells. In this work, N-doped carbon nanofibers encapsulated Fe1-xS nanoparticles composite (denoted as Fe1-xS/N-CNFs) was synthesized via electrospinning technique and following thermal treatment. Take advantage of the flexible web-like structure constructed by continuous fibers, the as-obtained membrane can be directly utilized as free-standing anodes for SIBs. Besides, the well confinement of CNFs can effectively buffer volume changes and prevent aggregation of active material. As a result, the as-obtained electrode achieved outstanding sodium storage performances. Specifically, a reversible discharge capacity of 549.1 mA h g−1 can be delivered at 0.1 A g−1. After 800 cycles at 1 A g−1, a specific capacity of 241.1 mA h g−1 still could be obtained, manifesting excellent cyclic stability of the composite. •Fe1-xS/N-CNFs hybrids with different contents of Fe1-xS were obtained.•Flexible structure feature made Fe1-xS/N-CNFs used as free-standing anodes.•Carbon coating improves conductivity and prevents dissolution of intermediates.•N-doping induced defects into CNFs, which is beneficial for sodium storage.