Failure Mechanisms of Siox- Vs. Sife- Graphite Composite Anodes in Li-Ion Batteries

Mobile IT battery market is encountered to development of anode materials with high capacity and long cycle life due to increasing consumers’ demands for longer operation time. To meet this requirement, change of cathode material can be considered at first, but any candidates cannot beat LiCoO₂. Accordingly, it is natural to consider the capacity increase of the anode materials beyond 390mAh/g. To achieve this target, the mixture of graphite and Si materials should be modulated with controllable volume expansion of the composite.

Herein, we assembled full lithium ion cells containing SiOx- and SiFe- graphite (SiOx-G, SiFe-G) composite anodes with reversible capacity of 450mAh/g. Using these two materials, we carried out further experiments to elucidate the capacity fading mechanisms using XPS, XRD, HR-TEM, EDS etc. Preliminary result showed that electrolyte decomposition degree with each anode materials upon increasing cycle number significantly affected its structural stability.