Submicron-sized α-Fe2O3 single crystals as anodes for high-performance lithium-ion batteries

Abstract Although Fe2O3 has been widely used as an anode material in lithium-ion batteries, its synthesis is complicated when a porous structure/nanoscale is needed to accommodate large volume variations and low electron conductivity. In this study, a submicron-sized α-Fe2O3 single-crystal (α-Fe2O3(SMSC)) is synthesized by directly annealing Fe(NO3)3⸳9H2O in an argon for the production of anodes for lithium-ion batteries. Unlike previously reported pure Fe2O3 which has poor electrochemical performance, α-Fe2O3(SMSC) exhibits excellent lithium storage properties. At a current density of 400 mA g−1, the discharge capacity is maintained at 970 mAh g−1 after 300 cycles. At a current density of 3200 mA g−1, the prepared anode shows a stable discharge capacity of ∼680 mAh g−1. During delithiation, the Li+ diffusion coefficient in the α-Fe2O3(SMSC) electrode is closely associated with the potential, which varies from 10−8 to 10−11 cm2 s−1. After the electrode was charged to 3.0 V, the products are shown to contain crystalline Li2Fe3O4, Fe3O4, and Li2O, but surprisingly, crystalline FeO is not detected. After combination with 30 wt% graphite, α-Fe2O3(SMSC) shows improved electrochemical properties, confirming that this crystal can be used as the main active component in high-performance anode composites.