Graphitic Carbon-Coated FeSe2 Hollow Nanosphere-Decorated Reduced Graphene Oxide Hybrid Nanofibers as an Efficient Anode Material for Sodium Ion Batteries

A novel one-dimensional nanohybrid comprised of conductive graphitic carbon (GC)-coated hollow FeSe 2 nanospheres decorating reduced graphene oxide (rGO) nanofiber (hollow nanosphere FeSe 2 @GC–rGO) was designed as an efficient anode material for sodium ion batteries and synthesized by introducing the nanoscale Kirkendall effect into the electrospinning method. The electrospun nanofibers transformed into hollow nanosphere FeSe 2 @GC–rGO hybrid nanofibers through a Fe@GC–rGO intermediate. The discharge capacities of the bare FeSe 2 nanofibers, nanorod FeSe 2 –rGO–amorphous carbon (AC) hybrid nanofibers, and hollow nanosphere FeSe 2 @GC–rGO hyrbid nanofibers at a current density of 1 A g −1 for the 150th cycle were 63, 302, and 412 mA h g −1 , respectively, and their corresponding capacity retentions measured from the 2nd cycle were 11, 73, and 82%, respectively. The hollow nanosphere FeSe 2 @GC–rGO hybrid nanofibers delivered a high discharge capacity of 352 mA h g −1 even at an extremely high current density of 10 A g −1 . The enhanced electrochemical properties of the hollow nanosphere FeSe 2 @GC–rGO composite nanofibers arose from the synergetic effects of the FeSe 2 hollow morphology and highly conductive rGO matrix.