Oxygen-Vacancy Engineered SnO2 Dots on rGO with N-Doped Carbon Nanofibers Encapsulation for High-Performance Sodium-Ion Batteries

The widespread adoption of sodium-ion batteries (SIBs) remains constrained by the inherent limitations of conventional anode materials, particularly their inadequate electronic conductivity, limited active sites, and pronounced structural degradation during cycling. To overcome these limitations, we propose a novel redox engineering approach to fabricate oxygen-vacancy-rich SnO2dots anchored on reduced graphene oxide (rGO), which are encapsulated within N-doped carbon nanofibers (denoted as ov-SnO2/rGO@N-CNFs) through electrospinning and subsequent carbonization. The introduction of rich oxygen vacancies establishes additional sodium intercalation sites and enhances Na+diffusion kinetics, while the conductive N-doped carbon network effectively facilitates charge transport and mitigates SnO2aggregation. Benefiting from the well-designed architecture, the hierarchical ov-SnO2/rGO@N-CNFs electrode achieves remarkable reversible specific capacities of 351 mAh g−1after 100 cycles at 0.1 A g−1and 257.3 mAh g−1after 2000 cycles at 1.0 A g−1and maintains 177 mAh g−1even after 8000 cycles at 5.0 A g−1, demonstrating exceptional long-term cycling stability and rate capability. This work offers a versatile design strategy for developing high-performance anode materials through synergistic interface engineering for SIBs.