Unusual formation of alpha-Fe2O3 hexagonal nanoplatelets in N-doped sandwiched graphene chamber for high-performance lithium-ions batteries

Nowadays, 2D nanosheets or nanoplatelets have attracted great attention due to their wide applications. However, the synthesis of 2D alpha-Fe2O3 nanosheets with well-defined hexagonal shape is extremely challenging, because the selective growth along one specific facet is very hard to be realized. In our work, we studied the non-capping ligand mediated reaction within graphene layer chamber, and successfully synthesized alpha-Fe2O3 hexagonal nanoplatelets sandwiched between graphene layers (HP-Fe-G). These materials exhibit an improved electrochemical performance compared with the pre-existing alpha-Fe2O3 nanoparticles loaded graphene (G-Fe2O3) composites because of the uniqueness of such architectures: thin nanoplatelets, large enough sandwiched spaces to buffer the volume expansion and N-doped graphene. HP-Fe-G delivered an ultrahigh reversible capacity of 1100 mAh/g after 50 cycles, thus higher than their theoretical value (926 mAh/g); while G-Fe2O3 composites showed relatively low capacity retention even after only 20 cycles (582 mAh/g). In addition, HP-Fe-G also reveal superior rate capability, 887 mAh/g at 1C; in comparison, this value was only 135 mAh/g at 1C for G-Fe2O3. (C) 2012 Elsevier Ltd. All rights reserved.