Natural collagen fiber-enabled facile synthesis of carbon@Fe3O4 core–shell nanofiber bundles and their application as ultrahigh-rate anode materials for Li-ion batteries

Abstract

A C@Fe₃O₄ core–shell nanofiber bundle (C@Fe₃O₄NFB) was easily prepared using a natural collagen fiber (CF) as the biotemplate and carbon source. The as-prepared C@Fe₃O₄NFB features a continuous conductive pathway with dramatically accelerated electron and Li⁺ transport kinetics, thus exhibiting an ultrahigh-rate capability. Furthermore, the C@Fe₃O₄ core–shell structure is able to suppress the electrode pulverization due to the existence of the carbon nanofiber as an elastic buffering matrix, thus delivering long-term cycling stability. Based on electrochemical experiments, C@Fe₃O₄NFB delivered capacities of 839, 668, 422 and 301 mA h g⁻¹ at current densities of 0.2, 1.0, 5.0 and 10.0 A g⁻¹, respectively. At the current density of 1.0 A g⁻¹, the reversible capacity of C@Fe₃O₄NFB is as high as 632 mA h g⁻¹ in the 500th cycle, which accounts for 84.38% capacity of the 2nd cycle, suggesting a low capacity loss of 0.23 mA h g⁻¹ per cycle. Even after 2000 cycles at 5.0 A g⁻¹, the discharge capacity still reaches 354 mA h g⁻¹. This biotemplated synthesis approach provides a novel and interesting route for fabricating ultrahigh-rate anode materials of LIBs.