Metallic Sn has provoked tremendous progress as an anode material for sodium-ion batteries (SIBs).However,Sn anodes suffer from a dramatic capacity fading,owing to pulverization induced by drastic volume expansion during cycling.Herein,a flexible three-dimensional (3D) hierarchical conductive network electrode is designed by constructing Sn quantum dots (QDs) encapsulated in one-dimensional N,S codoped carbon nanofibers (NS-CNFs) sheathed within two-dimensional (2D) reduced graphene oxide (rGO) scrolls.In this ingenious strategy,1D NS-CNFs are regarded as building blocks to prevent the aggregation and pulverization of Sn QDs during sodiation/desodiation,2D rGO acts as electrical roads and bridges among NS-CNFs to improve the conductivity of the electrode and enlarge the contact area with electrolyte.Because of the unique structural merits,the flexible 3D hierarchical conductive network was directly used as binder-and current collectorfree anode for SIBs,exhibiting ultra-long cycling life (373 mAh g-1 after 5000 cycles at 1 A g-1),and excellent high-rate capability (189 mAh g-1 at 10 A g-1).This work provides a facile and efficient engineering method to construct 3D hierarchical conductive electrodes for other flexible energy storage devices.