Cactus-like iron oxide/carbon porous microspheres lodged in nitrogen-doped carbon nanotubes as anodic electrode materials of lithium ion batteries

A highly stable and active cactus-like Fe2O3/C micro-nano-structure, spiny nanosheets vertically pinned on porous microspheres, wrapped with a nitrogen-doped carbon nanotube hybrid (Fe2O3/C@NCNT), was first fabricated by a metal-catalyzed graphitization-nitridization driven tip-growth process and an air oxidation induced Kirkendall effect. When applied as an efficient anode material for high-performance LIBs, the novel Fe2O3/C@NCNT composite delivers a high reversible capacity of 994.9 mA h g(-1) at a current density of 100 mA g(-1) (0.1C) with an excellent cycling stability of 944.7 mA h g(-1) after 600 cycles at 1 A g(-1), as well as a good rate performance (768 mA h g(-1) at 5C), showing great potential as an active and stable anode for high energy density Li-ion batteries. Such good performances could be attributed to the hierarchical structure with open porosity, abundant exposed nanosheets and bifunctional NCNT matrix (confining scaffolds and conducting networks), which promote electron-ion transport, enlarge the electrode-electrolyte contact area and withstand large volume variation upon cycling. More than these, we have proposed a new route to oxidizing tip capped metal carbide nanotubes to open the endpoints of NCNTs and synthesize a more-special structural metal oxide-based anode material with extraordinary electrochemical performance in LIBs.