Design and synthesis of high-silicon silicon suboxide nanowires by radio-frequency thermal plasma for high-performance lithium‐ion battery anodes

Silicon monoxide (SiO) is one of the most promising anode materials due to its high capacity and improved cycle stability. The lithium silicates (LixSiOy) and lithium oxide (Li2O) formed during the first lithiation can serve as a buffer matrix to restrain the volume change of internal silicon (Si), however, which also lows the initial coulombic efficiency (ICE). High-silicon silicon suboxide (SiOx) seems desirable due to the generation of less but enough LixSiOy/Li2O matrix. However, it is challenging to verify that all Si is protected by the matrix. In this work, SiO0.4 nanowires with Si shielded by SiOx are synthesized using thermal plasma. The interwoven structure composites of carbon-coated SiO0.4 and carbon nanotubes (SiO0.4/[email protected]) are then synthesized. As an electrode with a high loading of 2.2 mg cm−2, SiO0.4/[email protected] shows a 12.7 % increase in ICE (81.9 %) and a 34.6 % increase in capacity (1993 mAh/g/4.4 mAh cm−2 at 0.2 A/g for 300 cycles) in comparison to SiO1/[email protected] SiO0.4/[email protected] also shows outstanding high-rate cycle performance (1440 mAh/g at 3.0A/g for 2000 cycles). Significantly, when 5 wt% SiO0.4/[email protected] is added as an additive to commercial graphite (Gr), the capacity of a standard LiNi0.8Co0.15Al0.05O2//Gr 18,650 battery improves by 20.6 %.