Strongly coupled 1D sandwich-like C@Fe3O4@C coaxial nanotubes with ultrastable and high capacity for lithium-ion batteries

Sandwich-like carbon/metal oxide hybrids are expected to achieve some strong synergetic effects besides all the desired functions of each constituent and exhibit excellent lithium ion storage properties. In this work, strongly coupled 1D sandwich-like C@Fe3O4@C coaxial nanotubes with high surface area are fabricated through a novel and scalable bottom-up synthesis strategy. In the rationally constructed architecture, the inner and outmost carbon layers are capable of not only enhancing the electronic/ionic conductivity of Fe3O4 but also protecting encapsulated Fe3O4 nanoparticles from being exposed directly to the electrolyte, leading to structural and interfacial stabilization of the Fe3O4 interlayer. In consequence, the C@Fe3O4@C nanotubes deliver a high reversible capacity of 900 mA h g−1 at 100 mA g−1, excellent rate capacity (650 mA h g−1 at 1000 mA g−1), and a prolonged cycling life (maintaining 1087 mA h g−1 for 150 cycles) for lithium ion batteries (LIBs), which are much better than those of Fe3O4 nanotubes and core–shell C@Fe3O4 nanotubes.