Ternary Fe₂O₃/Fe₃O₄/FeCO₃ Composite as a High-Performance Anode Material for Lithium-Ion Batteries

Fe-based oxides have been recognized as one of the most promising anode materials for lithium-ion batteries (LIBs) due to their theoretical capacities, low cost, eco-friendliness, and natural abundance. However, poor cycling stability and low rate capability severely hindered their practical applications. Compared to single-component materials, multicomponent composites are more capable of achieving optimal electrochemical performance for electrode materials due to their synergetic effect. In this work, a novel ternary Fe₂O₃/Fe₃O₄/FeCO₃ composite is fabricated by a facile hydrothermal method with FeCl₂·4H₂O and urea as raw materials. When evaluated as an anode material for LIBs, this ternary Fe₂O₃/Fe₃O₄/FeCO₃ composite exhibits excellent rate capability (with reversible capacities of 624, 488, and 270 mAh g^–1 at 1.0, 3.0, and 10.0 A g^–1, respectively) and remarkable cycling stability (with a reversible capacity of 779 mAh g^–1 after 300 cycles at 0.5 A g^–1 and 410 mAh g^–1 after 800 cycles at 3.0 A g^–1), which are much superior to those of the single-component Fe₂O₃ material. It is found that the ternary Fe₂O₃/Fe₃O₄/FeCO₃ composite possesses good structural integrity during cycling and fast electrochemical reaction kinetics, which result in excellent long-term cycling stability and enhanced high-rate capability. The results may provide clues for the rational structural design of high-performance Fe-oxide anode materials for next-generation LIBs.