Strongly coupled N-doped carbon/Fe3O4/N-doped carbon hierarchical micro/nanostructures for enhanced lithium storage performance

Abstract A strong interface coupling is of vital importance to develop metal oxide/carbon nanocomposite anodes for next-generation lithium ion batteries. Herein, a rational N-doped carbon riveting strategy is designed to boost the lithium storage performance of Fe3O4/N-doped carbon tubular structures. Polypyrrole (PPy) has been used as the precursor for N-doped carbon. N-doped carbon-riveted Fe3O4/N-doped carbon (N C@Fe3O4@N C) nanocomposites were obtained by pyrolysis of PPy-coated FeOOH@PPy nanotubes in Ar atmosphere. When tested as an anode for LIBs, the N C@Fe3O4@N C displays a high reversible discharge capacity of 675.8 mA h g−1 after 100 cycles at a current density of 100 mA g−1 and very good rate capability (470 mA h g−1 at 2 A g−1), which significantly surpasses the performance of Fe3O4@N C. TEM analysis reveals that after battery cycling the FeOx particles detached from the carbon fibers for Fe3O4@N C, while for N C@Fe3O4@N C the FeOx particles were still trapped in the carbon matrix, thus preserving good electrical contact. Consequently, the superior performance of N C@Fe3O4@N C is attributed to the synergistic effect between Fe3O4 and N-doped carbon combined with the unique structure properties of the nanocomposites. The strategy reported in this work is expected to be applicable for designing other electrode materials for LIBs.