Hollow Core–Shell Mesospheres of Crystalline SnO₂ Nanoparticle Aggregates for High Capacity Li⁺ Ion Storage

Crystalline SnO 2 nanoparticles were successfully assembled into a higher-order nanostructure of hollow core–shell mesospheres by a simple and environmentally benign procedure consisting of solvothermal synthesis and postsynthesis calcination. Carbon mesospheres laden with crystalline SnO 2 nanoparticles were formed, using a suitably formulated water−ethanol mixture, as the sole product of solvothermal synthesis from tin and carbon precursors. Subsequent calcination compressed the SnO 2 nanoparticles into stable hollow core–shell mesospheres. The carbon in the mesospheres played the constructive role of templating the final product morphology during the carbon removal process. This method of preparation is simple, low cost, and could be conveniently scaled up for volume production. This unique SnO 2 nanostructure could store an exceedingly large amount of Li +, and it cycled well as a phase-pure SnO 2 anode.