Ordered sandwich silicon quantum dot/Fe3O4/reduced graphene oxide architectures for high-performance lithium-ion batteries

Abstract

Iron-based oxides are one of the most promising anode materials for lithium-ion batteries (LIBs) because of their high theoretical capacity, low cost, and eco-friendliness. However, its poor cycle stability and low-rate performance limit its wide application. In this work, a novel ordered sandwich-structured nanocomposite consisting of Fe3O4, silicon quantum dots (Si-QDs), and reduced graphene oxide (rGO) is synthesized via a self-assembly approach combined with subsequent annealing. Si-QDs are vital to guide the uniform formation and homogeneous distribution of nano-sized Fe3O4 on the rGO nanosheets. The resultant Si-QDs/Fe3O4/rGO composite possesses a unique ordered sandwich structure, in which Si-QDs and Fe3O4 particles are evenly anchored on rGO nanosheets. Si-QDs/Fe3O4/rGO delivers high specific capacity, outstanding cycling stability, and rate capability. At a current density of 100 mA·g−1, it displays an initial discharge-specific capacity of 1489.6 mAh·g−1 and maintained a specific capacity of 1367.1 mAh·g−1 after 80 cycles. The crucial effect of Si-QDs on the composite's morphology, structure, and electrochemical performances is deeply investigated by corresponding characterizations. The preparation strategy may be introduced in other metal-oxide-based nanocomposites with ordered sandwich structures and points out an ingenious way to design anode materials for high-performance LIBs.