α-Fe2O3@CNSs nanocomposites as superior anode materials for lithium-ion batteries

The nanocomposite of hematite@carbon nanosprings (α-Fe2O3@CNSs) was synthesized by simple precipitation and following heat treatment, in which the amount of α-Fe2O3 can be easily controlled by changing the synthesis conditions. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electronic microscopy (SEM), Brunau–Emmertt–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the as-synthesized nanocomposite. When applied as anode in Li-ion batteries (LIBs), the effect of α-Fe2O3/CNSs weight ratio on electrochemical performance of α-Fe2O3@CNSs nanocomposite has been researched. Enhancing the amount of α-Fe2O3 in nanocomposite would make the increase of specific capacity, but led to the degradation of cyclic stability and rate capability. The electrode of S-FeC (with weight ratio of CNSs/α-Fe2O3 about 4:1) could deliver a charge capacity of 527.6 mAh g−1at 0.2 C with excellent cyclability (96.9% capacity retention after 50 cycles), and retained 343.3 mAh g−1even at the rate of 5.0 C. In comparison with pure CNSs and α-Fe2O3, the improved cycling performance, specific capacity and rate capability of S-FeC should be mainly attributed to the combined effects of uniformly dispersed nanosized α-Fe2O3 particles and the highly strong network of CNSs.

► The nanocomposite of α-Fe2O3@CNSs has been successfully prepared and applied as anode of Li-ion batteries.
► The α-Fe2O3/CNSs weight ratio has a crucial effect on the electrochemical performance of α-Fe2O3@CNSs.
► Enhancing the amount of α-Fe2O3 in nanocomposite would make the increase ofspecific capacity, but led to the degradation of cyclic stability and rate capability.
► The most appropriate amount of α-Fe2O3 in nanocomposite is 20 wt%.