Tin-functionalized silicon oxycarbide as a stable, high-capacity anode material for Na-ion batteries

Abstract

In this study tin-functionalized silicon oxycarbide, Sn/SiOC, composite anode materials are synthesized using a carbon-rich polysiloxane as the preceramic polymer and nano-sized SnO2, which converts to metallic tin via carbothermal reduction at approximately 700 °C. The in-situ Sn formation leads to a uniform distribution of tin particles within a carbon-rich SiOC matrix. Raman spectra show no significant changes despite the carbothermal reduction of SnO2. The composite material provides a stable reversible capacity of 234 mAh g-1. By adjusting the composition and pyrolysis temperature a reversible capacity of 131 mAh g-1 at a high current rate of 2380 mA g-1 is achieved.