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

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 carb on riveting strategy is designed to boost the lithium storage performance of Fe3O4/N-doped carbon tubular structures.Poly pyrrole(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@Fe3C)4@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.

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 m A h g-1after 100 cycles at a current density of 100 m A g-1and very good rate capability(470 mA h g-1at 2 A g-1),which significantly surpasses the performance of Fe3O4@N–C.TEM analysis reveals that after battery cycling the FeOxparticles detached from the carbon fibers for Fe3O4@N–C,while for N–C@Fe3O4@N–C the FeOxparticles 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 Fe3O4and 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.