Fe 2 O 3 /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 Fe 2 O 3 (Fe 2 O 3 /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 Fe 2 O 3 · Fe 2 O 3 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, Fe 2 O 3 /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 Fe 2 O 3 /N-C@SiO x particles as an alternative anode material for rechargeable batteries. Graphical abstract