Solvent-Free Encapsulation of Ultrafine SnO₂ Nanoparticles in N‑Doped Carbon for High-Capacity and Durable Lithium Storage

SnO₂ has drawn great attention in lithium storage owing to the high theoretical capacity and appropriate lithiation potential. However, the low intrinsic conductivity and substantial volume variation severely hinder its further application in lithium-ion batteries (LIBs). Herein, we report a solvent-free carbon-coating strategy to encapsulate ultrafine SnO₂ nanoparticles into N-doped carbon. The effective coupling of SnO₂ nanoparticles with high activity and N-doped carbon with high conductivity and mechanical stability provides the obtained SnO₂@NC with a high reversible capacity of over 880 mAh g^–1 with satisfactory durability. In situ transmission electron microscopy (TEM) characterization reveals that even with encapsulation in mechanically stable N-doped carbon, pulverization of SnO₂ nanoparticles is unavoidable. However, the obtained SnO₂@NC demonstrates excellent structural stability upon cycling. The scalable solvent-free synthesis, high capacity, and ideal durability make SnO₂@NC a competitive LIB anode material.