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Fe3O4–carbon nanocomposites have been synthesized simply with a hydrothermal method free of template that is followed by an annealing process. The morphological and compositional analysis reveals that the inter-separated Fe3O4 nanocrystals with a size of ~10 nm are homogeneously embedded within the mesoporous carbon matrix. The interesting configuration is evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Benefiting from the advantages of good buffering and electric conductivity, the nanocomposite delivers an initial capacity of 1706 mAh g−1 at 0.2 C (1 C = 1 A g−1). Besides excellent lithium storage capability, it exhibits a superior cycling stability with more than 100% capacity retention after 100 cycles at 0.2 C and 1 C. When successively discharging at variable rates, the nanocomposite retains a reversible capacity of 1249 mAh g−1 at 0.1 C, 690 mAh g−1 at 1 C, and 311 mAh g−1 at 10 C. With excellent capability and rate performance, the Fe3O4–carbon nanocomposites may be a promising anode material of lithium ion batteries (LIBs) for the green large-scale production. [ABSTRACT FROM AUTHOR]

Novel nanostructures, e.g. core–shell or yolk–shell, sword–sheath, coaxial nanotubes, etc., are extensively explored for their potential application in modifying electrode durability in lithium-ion batteries (LIBs). Herein, hybrid nanostructures of monodisperse tin dioxide nanocrystals inclusion in highly ordered mesotunnels of mesoporous carbon (CMK-3) are hydrothermally synthesized. Benefiting from ultrafine nanocrystals of mainly 2 nm or so and their good distribution throughout the highly ordered tunnels and the outer surface of the CMK-3, the hybrid shows a strongly coupled synergistic effect. When used as anode materials for LIBs, the hybrid composite exhibits excellent cycling and rate performance superior to both components involved with high reversible capacity retention above 95% for 200 cycles and recoverable initial reversible capacity at large rates of 10 A g−1. Insights into the electrochemical process reveal the total capacity is contributed by two different factors: redox capacitance and interfacial capacitance. Once solid electrolyte interfaces (SEIs) are formed, the hybrid composite exhibits stable interfaces and robust structures indicated by the enhanced interfacial capacitance. [ABSTRACT FROM AUTHOR]