Preparation and sodium-ion storage performance of bimetallic oxygen sulfide composite hollow carbon fibers

In sodium-ion storage technologies, the high radius of Na + causes slow diffusion kinetics, and the repeated sodiation/desodiation will damage the electrode structure. Herein, the iron-tin oxysulfide (FSOS) is confined in the N-doped hollow carbon nanofibers through a coaxial electrospinning. FSOS with multiple cationic valences can promote the adsorption and redox reaction of Na + , which facilitate electrolyte penetration. For anode material in sodium-ion batteries (SIBs), FSOS@NSC offers competitive cycling performance (246 mA h g −1 after 1500 cycles with capacity retention of 80.3%) as well as high-rate capability (242 mA h g −1 ), and a sodium-ion capacitor device (SICs) with a large operating voltage window by using FSOS@NSC as the anode (0.01–4.0 V). FSOS@NSC//AC hybrid system delivers capacity retention of 74.6% at 20 A g −1 after 2000 cycles and high energy density (100.5 W h kg −1 ). This research offers a method for creating a new generation by anion regulation with partial sulfuration. Graphical abstract