Mechanical stability for nanostructured Sn- and Si-based anodes

The most promising materials that can be used as anodes in next generation rechargeable Li batteries are Sn and Si. Upon lithiation, however, both Sn and Si experience a 300% volume expansion, which results in significant fracture, and therefore their commercial use is inhibited. Extensive experimental research has yielded that embedding or attaching Si or Sn nanoparticles in a carbon/graphite matrix diminishes their mechanical damage and allows for electrochemical stability. The present study will show that linear elasticity can predict the capacity retention of such nanocomposites by predicting their mechanical stability upon Li-insertion. In particular (i) a previously developed theoretical model will be related to experimental observations on Si/sol-gel-graphite nanocomposite anodes, (ii) electron microscopy images will be presented on the fracture of cycled SnO₂/C nanopowders, and a theoretical model will be applied to predict the SnO₂ particle dimensions that will limit such fracture.