Synthesis and characterization of SiO2/C composite nanofibers as free-standing anode materials for Li-ion batteries

One dimensional SiO2/C composite nanofibers were successfully synthesized from precursor solutions with polyvinylpyrrolidone (PVP) as a carbon source by electrospinning with two-step heat treatment, comprising preoxidation at 280 degrees C in the air followed by annealing at 700 degrees C for 1 h in a reduced atmosphere. The effects of the preoxidation treatment on the morphology, chemical structure, and electrochemical properties of the synthesized materials were studied by scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, and solid- state nuclear magnetic resonance spectroscopy. The two-step heat treatment had strong positive impacts not only on the morphology but also on the structure and electrochemical performance of the materials. Furthermore, free-standing SiO2/C composite nanofiber mats (FS-SiO2/C-CNFMs) were prepared from precursor solutions with different PVP concentrations by electrospinning with the two-step heat treatment. The FS-SiO2/C-CNFM obtained from the precursor solution with 5 wt.% PVP had a geometric mean diameter of 79 nm and a specific surface area of 642 m(2) g(-1). It exhibited high initial discharge and charge capacities of 1800 and 984 mA h (SiO2-g)(-1), respectively, and finally retained a charge capacity of 754 mA h (SiO2-g)(-1) after 200 cycles with 100% Coulombic efficiency. (C) 2019 Elsevier Ltd. All rights reserved.