Fe/Fe3C modification to effectively achieve high-performance Si–C anode materials

Abstract

For high-performance silicon–carbon (Si–C)-based anode materials used in high-energy-density lithium-ion batteries (LIBs), there is an urgent need to rationally construct a stable solid electrolyte interface (SEI) film and load a high proportion of silicon content, which is closely related to the capacity and cycling stability of the electrode. Herein, composites of Fe/Fe₃C-modified carbon nanofiber–coated Si nanoparticles (Fe/Fe₃C–Si@CNFs) were synthesized via a simple electrospinning method. These composites effectively overcome the volume change effect, poor interfacial compatibility and low conductivity, delivering excellent LIB performance. Tested at 2.0 A g⁻¹, Fe/Fe₃C–Si@CNFs provides a high reversible capacity of 956.5 mA h g⁻¹ with a coulombic efficiency of more than 99.5% even after 4000 ultra-long stable cycles. The high conductivity of the Fe/Fe₃C embedded in the CNF framework can promote e⁻ transfer and boost the Li⁺ diffusion kinetics in the electrode. The catalytic activity of Fe/Fe₃C helps to enhance the interfacial compatibility, grow a balanced stable SEI film and promote the long-cycle stability of the electrode at room temperature.