The Role of Metallic Fe and Carbon Matrix in Fe2O3/Fe/Carbon Nanocomposite for Lithium-Ion Batteries

A comparative study is made on the cycle and rate performance of three Fe2O3-containing electrodes. The first electrode is made from a commercial nanosized (< 100 nm) Fe2O3 powder, whereas the second is made from a carbon-supported nanosized Fe2O3 (Fe2O3/carbon composite). The third electrode is prepared by modifying the second, incorporating the metallic Fe into the Fe2O3 particles (Fe2O3/Fe/carbon composite). Three electrodes show the following performance order in the cycle retention and rate capability: nanosized Fe2O3 < Fe2O3/carbon composite < Fe2O3/Fe/carbon composite. The reverse order is, however, found on both the electrode volume change and the evolution of internal resistance. Thus, the best performance observed with the Fe2O3/Fe/carbon composite electrode has been ascribed to the presence of a carbon support and metallic Fe, both of which seem to play two important roles: the buffering action against the massive volume change in Fe2O3 particles and providing an electronically conductive network within the swollen electrode layer.