The precise synthesis of twin-born Fe3O4/FeS/carbon nanosheets for high-rate lithium-ion batteries

Metal oxides/sulfides have been considered as promising anode candidates for use in next-generation lithium-ion batteries (LIBs), but the large volume changes and poor electron and ion conductivities limit their practical applications. Here, twin-born Fe3O4/FeS/carbon nanosheets (TB-FeOSC-NS) were precisely fabricated for the first time by using MIL-88b(Fe) as a self-sacrificing template. By adjusting the amount of citric acid and the annealing temperature, the structure and phase composition could be accurately controlled. Benefitting from its unique structure, TB-FeOSC-NS can provide an abundant contact interface with electrolytes and active sites for redox reactions, providing a short diffusion path for electrons and ions. Therefore, as an anode material for use in LIBs, the TB-FeOSC-NS electrode exhibits admirable electrochemical performance, including a high specific capacity, excellent cycling stability, and superior rate performance, with a high capacity of 400 mA h g(-1) at an ultrahigh current density of 20 A g(-1). More importantly, this work deepens our understanding of the precise synthesis of heterostructured materials for electrochemical energy storage and the synergistic modulation of morphologies, phase compositions, and interfaces.

Automated summary

Metal oxides/sulfides have been explored as promising anode candidates for next-generation lithium-ion batteries, but their practical applications have been limited by volume changes and poor conductivities. In this study, twin-born Fe3O4/FeS/carbon nanosheets were precisely fabricated and exhibited excellent electrochemical performance as an anode material for LIBs, with high specific capacity, cycling stability, and rate performance. This work deepens the understanding of precise synthesis of heterostructured materials for electrochemical energy storage.