Ytterbium-Induced In Situ Formation of Fe₂O₃/YbFeO₃ Heterostructure: A Highly Stable Capacitive Anode Material for...

Iron oxide is a promising candidate for a lithium-ion battery anode material due to its high theoretical capacity, yet it suffers from poor conductivity and severe volume expansion. This work utilizes rare-earth ytterbium (Yb) modification to engineer the crystal structure of iron oxide via in situ construction of a Fe₂O₃/YbFeO₃ heterostructure. Ytterbium was selected for its unique electronic structure and larger ionic radius, enabling adjustment of the local electronic environment and enhancing structural tolerance. Using FeCl₃ and YbCl₃ as precursors, a Fe-Yb composite with a molar ratio of 20:1 was synthesized via hydrothermal synthesis, followed by calcination at 700, 800, and 900 °C. The calcination temperature critically influenced electrochemical performance, with the 800 °C-treated sample (FeYb-800) exhibiting optimal characteristics: it retained a high reversible capacity of 700 mAh g^-1 after 100 cycles and maintained a stable capacity of ~600 mAh g^-1 after 500 cycles at 0.5 A g^-1. Structural analysis indicates that ytterbium incorporation promotes the formation of a porous Fe₂O₃/YbFeO₃ heterostructure. This architecture not only provides abundant active sites but also mitigates volume changes during cycling, effectively suppressing electrode degradation. This study successfully validates a viable strategy for fabricating high-performance anode materials with promising potential for high-energy-density lithium-ion batteries via rare-earth ytterbium modification.