Self-supporting carbon-rich SiOC ceramic electrodes for lithium-ion batteries and aqueous supercapacitors

Abstract

Fabrication of precursor-derived ceramic fibers as electrodes for energy storage applications remains largely unexplored. Within this work, three little known polymer-derived ceramic (PDC)-based fibers are being studied systemically as potential high-capacity electrode materials for electrochemical energy devices. We report fabrication of precursor-derived SiOC fibermats via one-step spinning from various compositions of siloxane oligomers followed by stabilization and pyrolysis at 800 °C. Electron microscopy, Raman, FTIR, XPS, and NMR spectroscopies reveal transformation from polymer to ceramic stages of the various SiOC ceramic fibers. The ceramic samples are a few microns in diameter with a free carbon phase embedded in the amorphous Si-O-C structure. The free carbon phase improves the electronic conductivity and provides major sites for ion storage, whereas the Si-O-C structure contributes to high efficiency. The self-standing electrodes in lithium-ion battery half-cells deliver a charge capacity of 866 mA h gelectrode-1 with a high initial coulombic efficiency of 72%. As supercapacitor electrode, SiOC fibers maintain 100% capacitance over 5000 cycles at a current density of 3 A g-1.