Optimization of SnO₂ Nanoparticles Confined in a Carbon Matrix towards Applications as High-Capacity Anodes in Sodium-Ion Batteries

SnO₂/carbon composites including amorphous carbon and graphene or carbon nanotubes are synthesized by a gas-liquid interfacial approach and subsequent annealing process. The effect of the carbon source and the conductive additive on the electrochemical performance is investigated by galvanostatic charge-discharge tests. SnO₂@Glucose/Graphene (SnO₂@Glu/G) composites as anodes of sodium-ion batteries show the best electrochemical performance, delivering 306 mA h g⁻¹ after 100 cycles at 0.1 A g⁻¹ between 0.01-3 V, while exhibiting 278 and 226 mA h g⁻¹ at 1 and 2 A g⁻¹, respectively. The mechanism of improved electrochemical performance for graphene is researched in detail. The results reveal a porous structure with fine SnO₂ particles due to the introduction of graphene oxide, and an effective electron charge transfer network from the graphene increases its reversible capacity, rate performance and cycling performance.