Centrifugally spun silica fibers for lithium-ion battery anodes: structure and cycling stability

Introduction: Silicon dioxide (SiO2) fiber structures have attracted attention as alternative anode materials for lithium-ion batteries because of their ability to improve cycling stability compared to commercial silicon particles. Materials and methods: SiO2 composite fibers were prepared by centrifugal spinning of polyvinylpyrrolidone (PVP)/SiO2 precursor solutions followed by calcination at 500–700 °C for different holding times to produce short-fiber composites and micro-belt SiO2 fiber structures. The morphology and crystal structure of the SiO2 short fibers and micro-belts were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). Electrochemical performance was evaluated using CR2032 half-cells. Results: The calcination temperature strongly influenced morphology, oxidation behavior, and electrochemical performance. Samples treated at 500 °C retained short-fiber morphologies but exhibited unstable cycling behavior because of incomplete oxidation. The sample calcined at 600 °C for 3 h exhibited improved cycling stability associated with a more oxidized surface and belt-like morphology. Samples treated at 700 °C showed collapsed structures and reduced reversible capacity. Conclusions: The results demonstrated that the calcination conditions strongly influenced the relationship between morphology evolution, oxidation state, and electrochemical stability in centrifugally spun SiO2 composite fibers. These findings provide a foundation for the future development of SiO2 fiber structures for use as composite anodes in lithium-ion batteries.