Grapecluster-like Fe3O4@C/CNT nanostructures with stable Li-storage capability

Magnetite Fe3O4 has emerged as an important type of Li-storage electrode material for rechargeable battery applications. The engineering and synthesis of high-performance Fe3O4 with large capacity and stable cyclability via a facile approach is desirable but remains challenging. Here, we adopt a simple three-step method to synthesize a carbon coated magnetite/carbon nanotube (CNT) grapecluster nanostructure as an efficient Li-storage electrode material. The CNT network serves as a highly conducting and porous scaffold facilitating electron and ion transport, while the carbon coating layer provides a flexible space for buffering of strain and stress upon electrochemical cycling. The prepared Fe3O4@C/CNT grapecluster structures show a much improved performance compared with the Fe3O4@C counterpart. Specifically, the Fe3O4@C/CNT hybrid structure with 20 wt% CNT loading delivers a reversible capacity exceeding 900 mA h g−1 at 60 mA g−1, and retains 693 mA h g−1 at 300 mA g−1 after 200 cycles. The Fe3O4@C/CNT structure also exhibits a favourable rate capability, demonstrating the potential of Fe3O4@C/CNT hybrids as an electrode material for rechargeable batteries.