Self-assembly of Fe2O3/reduced graphene oxide hydrogel for high Li-storage

A novel three-dimensional (3D) Fe2O3/reduced graphene oxide (RGO) hydrogel (FGH) is prepared by a facile hydrothermal strategy. In this composite hydrogel, RGO sheets self-assemble into an interconnected macroporous framework and Fe2O3 nanotubes encapsulate into RGO layers. The FGH delivers high rate capacities of 850, 780, 550, and 400 mAh/g at current densities of 200, 400, 600, and 800 mA/g, respectively. The specific capacity can still maintain at ∼600 mAh/g after 70 cycles, which greatly outperforms that of pure Fe2O3 nanotubes (∼60 mAh/g after 70 cycles). The improved electrochemical performance is ascribed to the unique macroscopic structure which is beneficial for enlarging the active surface area, shortening the electron/ion pathway, accommodating the volume change of Fe2O3 nanotubes, and preventing the aggregation of both Fe2O3 nanoparticles and RGO sheets.