Fe₂O₃/N-doped carbon-modified SiO_x particles via ionic liquid as anode materials for Li-ion batteries

SiO_x is considered a promising alternative anode material for Li-ion batteries because of its higher theoretical capacity and safety compared with those of carbonaceous materials. In this study, SiO_x with N-doped carbon containing Fe₂O₃ (Fe₂O₃/N-C@SiO_x) was synthesized through mechanical milling, and its electrochemical properties and applicability as a stable anode material for Li-ion batteries were evaluated. Characterization data show that silicon, oxygen, carbon, nitrogen, and iron are shown to be uniformly distributed in the particles, which consist of amorphous SiO and N-doped amorphous carbon containing Fe₂O₃· Fe₂O₃ and N-doped carbon synergistically act as a reinforcing matrix that can mitigate internal breakdown between particles due to the volume expansion of the SiO_x active materials while increasing electrical conductivity. As a result, Fe₂O₃/N-C@SiO_x delivers a reversible capacity of 883 mA h g⁻¹ at 100 mA g⁻¹ for up to 100 cycles, corresponding to a capacity retention of 77%. Furthermore, it attains high reversible capacities of 671 and 415 mA h g⁻¹ at 1000 and 3000 mA g⁻¹, respectively, which are more than twice as high as that of bare SiO_x (336 mA h g⁻¹) measured at 1000 mA g⁻¹. These findings demonstrate the potential of Fe₂O₃/N-C@SiO_x particles as an alternative anode material for rechargeable batteries. Graphical abstract: [Figure not available: see fulltext.]