Self-assembled graphene-constructed hollow Fe2O3 spheres with controllable size for high lithium storage

Abstract

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.