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

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. 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. 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. 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.