CNT@Fe 3 O 4 @C Coaxial Nanocables: One‐Pot, Additive‐Free Synthesis and Remarkable Lithium Storage Behavior

By using carbon nanotubes (CNTs) as a shape template and glucose as a carbon precursor and structure‐directing agent, CNT@Fe 3 O 4 @C porous core/sheath coaxial nanocables have been synthesized by a simple one‐pot hydrothermal process. Neither a surfactant/ligand nor a CNT pretreatment is needed in the synthetic process. A possible growth mechanism governing the formation of this nanostructure is discussed. When used as an anode material of lithium‐ion batteries, the CNT@Fe 3 O 4 @C nanocables show significantly enhanced cycling performance, high rate capability, and high Coulombic efficiency compared with pure Fe 2 O 3 particles and Fe 3 O 4 /CNT composites. The CNT@Fe 3 O 4 @C nanocables deliver a reversible capacity of 1290 mA h g −1 after 80 cycles at a current density of 200 mA g −1 , and maintain a reversible capacity of 690 mA h g −1 after 200 cycles at a current density of 2000 mA g −1 . The improved lithium storage behavior can be attributed to the synergistic effect of the high electronic conductivity support and the inner CNT/outer carbon buffering matrix.