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

The nanocomposite of hematite@carbon nanosprings (alpha-Fe2O3@CNSs) was synthesized by simple precipitation and following heat treatment, in which the amount of alpha-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 alpha-Fe2O3/CNSs weight ratio on electrochemical performance of alpha-Fe2O3@CNSs nanocomposite has been researched. Enhancing the amount of alpha-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/alpha-Fe2O3 about 4:1) could deliver a charge capacity of 527.6 mAh g(-1) at 0.2 C with excellent cyclability (96.9% capacity retention after 50 cycles), and retained 343.3 mAh g(-1) even at the rate of 5.0 C. In comparison with pure CNSs and alpha-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 alpha-Fe2O3 particles and the highly strong network of CNSs. (C) 2011 Elsevier Ltd. All rights reserved.