Nitrogen/chlorine-doped carbon nanodisk-encapsulated hematite nanoparticles for high-performance lithium-ion storage

Iron oxide (Fe₂O₃) is an intriguing anode material of electrochemical energy storage systems such as rechargeable batteries. The rational design of its nanostructure at mild condition to cope with the issues of low reversible capacity and sluggish kinetics is required. Herein, an efficient, facile, and potentially large-scale synthesis approach using the precursor of laminated iron oxychloride@polyaniline heterostructure and mild annealing is developed, yielding unique Fe₂O₃@carbon nanocomposites with hematite nanoparticles (∼20 nm) that embedded in nitrogen/chlorine-doped carbon nanodisk (N/Cl–C). Given the benefit of abundant active sites, good chemical contact between carbon and Fe₂O₃, and robust composite structure, the as-prepared Fe₂O₃@N/Cl–C anode material delivers competent lithium-ion storage properties, including high reversible capacity of 1010 mAh g⁻¹ (based on the mass of the as-prepared nanocomposite) at 0.1 A g⁻¹, decent rate performance upon a rigorous current change, and superior cycling stability with 955 mAh g⁻¹ after 180 cycles as well as a sustained Coulombic efficiency of about 99%. This structural design may provide a new avenue for achieving efficient iron oxide-based materials in chemical and electrochemical applications such as catalysis, lithium-ion batteries, and sodium-ion batteries.