Microemulsion Syntheses of Sn and SnO ₂-Graphite Nanocomposite Anodes for Li-Ion Batteries

Nanostructured SnO ₂, SnO ₂-graphite, and Sn-graphite composites were prepared by microemulsion techniques using Tergitol 15-S-5 as the surfactant. The particle size of the pristine SnO ₂ nanoparticles was typically between 12 and 14 nm. For the composites, Sn and SnO ₂ nanoparticles 7-10 nm in size with narrow size distribution were uniformly dispersed on graphite, indicating the positive effect of graphite in maintaining smaller particle size. These Sn-based nanocomposites are multiple Li host systems with good cycling performance in Li-ion battery applications. The improved cyclability is perceived to be a combination of the use of well dispersed Sn or SnO ₂ nanoparticles resistant to particle agglomeration, and the presence of a soft graphite matrix to buffer the volume changes in the Li-Sn reactions. In addition, the Sn-graphite nanocomposites exhibited a SnO-shell-Sn-core structure and slightly lower first cycle capacity losses.