Robust SnO_2−x Nanoparticle-Impregnated Carbon Nanofibers with Outstanding Electrochemical Performance for Advanced Sodium-Ion Batteries

The sluggish sodium reaction kinetics, unstable Sn/Na₂O 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 SnO_2−x nanoparticles with well-defined void space in porous carbon nanofibers (denoted SnO_2−x/C composites) that address the issues noted above for advanced SIBs. Notably, SnO_2−x/C composites can be readily exploited as the working electrode, without need for binders and conductive additives. In contrast to past work, SnO_2−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.