Energetic-materials-driven synthesis of graphene-encapsulated tin oxide nanoparticles for sodium-ion batteries

By evenly mixing polytetrafluoroethylene-silicon energetic materials (PTFE-Si EMs) with tin oxide (SnO₂ ) particles, we demonstrate a direct synthesis of graphene-encapsulated SnO₂ (Gr-SnO₂ ) nanoparticles through the self-propagated exothermic reaction of the EMs. The highly exothermic reaction of the PTFE-Si EMs released a huge amount of heat that induced an instantaneous temperature rise at the reaction zone, and the rapid expansion of the gaseous SiF₄ product provided a high-speed gas flow for dispersing the molten particles into finer nanoscale particles. Furthermore, the reaction of the PTFE-NPs with Si resulted in a simultaneous synthesis of graphene that encapsulated the SnO₂ nanoparticles in order to form the core-shell nanostructure. As sodium storage material, the graphene-encapsulated SnO₂ nanoparticles exhibit a good cycling performance, superior rate capability, and a high initial Coulombic efficiency of 85.3%. This proves the effectiveness of our approach for the scalable synthesis of core-shell-structured graphene-encapsulated nanomaterials.