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

Abstract

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.