Sn²⁺-Regulated Synthesis of a Bone-like Fe₃O₄@N-Doped Carbon Composite as the Anode for High-Performance Lithium Storage

Iron-based oxides are a class of attractive anode materials for lithium-ion batteries by virtue of their high theoretical capacity, abundant resource, and low cost. Nevertheless, their practical applications in energy storage are seriously hampered by their inherent large volume expansion, poor conductivity, and sluggish reaction kinetics. Herein, we design a unique bone-like Fe₃O₄@N-doped carbon (B–Fe₃O₄@C) composite via a facile Sn²⁺-induced hydrothermal route. Taking advantage of a unique morphology, a thin carbon layer coating of about 5 nm, and in situ nitrogen doping, the as-prepared B–Fe₃O₄@C anode material demonstrates excellent lithium storage capability. It delivers a high first discharge capacity (1480.3 mA h g^–1 at 0.1 A g^–1), superior cycling stability (a capacity fading of only 0.026% per cycle for 100 cycles at 0.1 A g^–1), and good rate capability (480.8 mA h g^–1 at 2 A g^–1). The theoretical analysis results indicate that the enhanced electrochemical performance mainly comes from the increased Li⁺ adsorption energy on the Sn-doped Fe₃O₄ surface. The present synthetic study also paves a way for the facile design of advanced electrode materials for next-generation energy storage and conversion.