Copper Nanoparticle-Incorporated Carbon Fibers as Free-Standing Anodes for Lithium-Ion Batteries

Copper-incorporated carbon fibers (Cu/CF) as free-standing anodes for lithium-ion batteries are prepared by electrospinning technique following with calcination at 600, 700, and 800 °C. The structural properties of materials are characterized by X-ray diffraction (XRD), Raman, thermogravimetry (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), and energy dispersive X-ray spectrometry (EDS). It is found that the Cu/CF composites have smooth, regular, and long fibrous morphologies with Cu nanoparticles uniformly dispersed in the carbon fibers. As free-standing anodes, the unique structural Cu/CF composites show stable and high reversible capacities, together with remarkable rate and cycling capabilities in Li-ion batteries. The Cu/CF calcined at 800 °C (Cu/CF-800) has the highest charge/discharge capacities, long-term stable cycling performance, and excellent rate performance; for instance, the Cu/CF-800 anode shows reversible charge/discharge capacities of around 800 mAh g−1 at a current density of 100 mA g−1 with stable cycling performance for more than 250 cycles; even when the current density increases to 2 A g−1, the Cu/CF-800 anode can still deliver a capacity of 300 mAh g−1. This excellent electrochemical performance is attributed to the special 1D structure of Cu/CF composites, the enhanced electrical conductivity, and more Li+ active positions by Cu nanoinclusion.