Stable anodes for lithium-ion batteries based on tin-containing silicon oxycarbonitride ceramic nanocomposites

Abstract

Tin nanoparticles are a promising candidate for Li-ion battery anodes to replace carbon materials due to their high theoretical Li-ion storage capacity (994 mAh/g), which is much higher than that of graphite (372 mAh/g). However, the poor cycling stability of tin emerged from large volume expansion, and contraction remains a challenging issue. To overcome these limitations, we designed Sn-containing silicon oxycarbonitride ceramic nanocomposites (Sn/SiOCN) by the chemical reaction of tin acetate with poly(vinyl)silazane Durazane 1800 in ice bath under argon, followed by the pyrolysis of as-obtained precursors at 1000 °C for 3 h under argon atmosphere. The Sn/SiOCN nanocomposites with different Sn contents are tested as anodes for lithium-ion batteries, delivering a high-discharge capacity of ∼320 mAh/g at a current density of 2220 mA/g and extremely long cycling stability even at high charging rates (approximately 90% of the capacity is maintained after 1000 cycles). The outstanding electrochemical performance of Sn/SiOCN nanocomposites can be attributed to the improved charge transfer process due to the incorporation of metallic Sn nanoparticles into the amorphous SiOCN ceramic matrix, as revealed by electrochemical impedance spectroscopy (EIS) characterization. In situ XRD results confirm the formation of lithium-rich alloy phase Li7Sn2 during the lithiation process.