Large and fast reversible Li-ion storages in Fe2O3-graphene sheet-on-sheet sandwich-like nanocomposites.

Fe2O3 nanosheets and nanoparticles are grown on graphene by simply varying reaction solvents in a facile solvothermal/hydrothermal preparation. Fe2O3 nanosheets are uniformly dispersed among graphene nanosheets, forming a unique sheet-on-sheet nanostructure. Due to the structure affinity between two types of two dimensional nanostructures, graphene nanosheets are separated better by Fe2O3 nanosheets compared to nanoparticles and their agglomeration is largely prevented. A large surface area of 173.9 m(2) g(-1) is observed for Fe2O3-graphene sheet-on-sheet composite, which is more than two times as large as that of Fe2O3-graphene particle-on-sheet composite (81.5 m(2) g(-1)). The sheet-on-sheet composite is found to be better suitable as an anode for Li-ion battery. A high reversible capacity of 662.4 mAh g(-1) can be observed after 100 cycles at 1000 mA g(-1). The substantially improved cycling performance is ascribed to the unique structure affinity between Fe2O3 nanosheets and graphene nanosheets, thus offering complementary property improvement.