Carbon nanotubes (CNTs) as superior support materials for functional nanoparticles (NPs) have been widely demonstrated.Nevertheless,the homogeneous loading of these NPs is still frustrated due to the inert surface of CNTs.In this work,a facile gas-phase pyrolysis strategy that the mixture of ferrocene and CNTs are confined in an isolated reactor with rising temperature is developed to fabricate a carbon-coated Fe3O4 nanoparticle/carbon nanotube (Fe3O4@C/CNT) composite.It is found the ultrasmall Fe3O4 NPs (＜ 10 nm) enclosed in a thin carbon layer are uniformly anchored on the surface of CNTs.These structural benefits result in the excellent lithium-ion storage performances of the Fe3O4@C/CNT composite.It delivers a stable reversible capacity of 861 mA· h· g-1 at the current density of 100 mA· g-1 after 100 cycles.The capacity retention reaches as high as 54.5％ even at 6000 mA·g-1.The kinetic analysis indicates that the featured structural modification improves the surface condition of the CNT matrix,and contributes to greatly decreased interface impendence and faster charge transfer.In addition,the post-morphology observation of the tested sample further confirms the robustness of the Fe3O4@C/CNT configuration.