Highly stable Fe2O3@Fe3O4@FeCO3 heterostructure anchored on graphene as the enhanced electrochemical performance of Li-ion battery anodes

Abstract

Fe-based oxides have received tremendous attention owing to its high capacity, low cost, controllable morphology, and immense natural reserves. However, their poor cycle stability hinders practical application. In the present paper, Fe2O3@Fe3O4@FeCO3/reduced graphene oxide (3-Fe/rGO) composite was synthesized by green and simple strategy. The particle size of 3-Fe heterostructure is reduced and dispersed evenly on the rGO surface. The 3-Fe/rGO composite exhibits excellent electrochemical performance as anode material in Li-ion batteries. The specific discharge capacities of 3-Fe/rGO composite are 868.7 mA g−1 after 200 cycles at 200 mA g−1 and 578.9 mA g−1 after 500 cycles at 2 A/g. The outstanding electrochemical properties arise from the effective synergy existing between FeCO3, Fe3O4, Fe2O3, and rGO. Considering the charge transfer and Li+ diffusion, 3-Fe/rGO composite shows excellent properties, indicating that the typical structure and excellent properties of rGO can aid in the coating and buffering of the expansion of 3-Fe heterostructure during the Li+ extraction and insertion processes, reducing the loss of irreversible capacity. Moreover, the conductivity of the electrode is significantly improved. This is an already established method to improve the electrochemical performance of Fe-based oxides, but the present work has added new dimensions to it.