Self-assembled graphene-constructed hollow Fe2O3 spheres with controllable size for high lithium storage
Graphene-constructed hollow Fe2O3 spheres (GHFs) were prepared by a one-pot hydrothermal process. The Fe2O3 particles were perfectly constructed using graphene sheets. This strategy was an easy method for the large-scale synthesis of GHFs. The size of Fe2O3 spheres ranged from 2000 nm to 50 nm and can be easily controlled by changing the weight ratio of GO to FeCl2, and the size greater than 250 nm shows a hollow structure obviously. As the anode material for lithium-ion batteries, the GHFs (300 nm) showed an excellent reversible capacity of 950 mA h g−1 after 50 cycles at a charge–discharge rate of 100 mA g−1, and delivered a reversible capacity as high as 640 mA h g−1 at a high rate of 1000 mA g−1. The outstanding electrochemical performance of GHFs can be attributed to the graphene-constructed hollow Fe2O3 spheres and the synergistic interaction between uniformly dispersed Fe2O3 particles and graphene. Moreover, the favorable performance of GHFs can be attributed to the reduced diffusion length of lithium, in which the hollow structure of Fe2O3 spheres played an important role.