Robust SnO2−x Nanoparticle‐Impregnated Carbon Nanofibers with Outstanding Electrochemical Performance for Advanced Sodium‐Ion Batteries

The sluggish sodium reaction kinetics, unstable Sn/Na2 O interface, and large volume expansion are major obstacles that impede practical applications of SnO2 -based electrodes for sodium-ion batteries (SIBs). Herein, we report the crafting of homogeneously confined oxygen-vacancy-containing SnO2-x nanoparticles with well-defined void space in porous carbon nanofibers (denoted SnO2-x /C composites) that address the issues noted above for advanced SIBs. Notably, SnO2-x /C composites can be readily exploited as the working electrode, without need for binders and conductive additives. In contrast to past work, SnO2-x /C composites-based SIBs show remarkable electrochemical performance, offering high reversible capacity, ultralong cyclic stability, and excellent rate capability. A discharge capacity of 565 mAh g-1 at 1 A g-1 is retained after 2000 cycles.