Monodisperse and homogeneous SiOx/C microspheres: A promising high-capacity and durable anode material for lithium-ion batteries

Monodisperse SiOx/C microspheres with tunable size (300–1000 nm) and well-controlled carbon content (~ 20–60 wt%) have been fabricated through a facile sol-gel method. The judicious selection of silicon and carbon precursors (vinyltriethoxysilane and resorcinol/formaldehyde) enables the formation of an homogeneous SiOx/C (x = 1.63) composite, in which the SiOx mainly exists as ultrafine nano-domains (<2 nm). Benefiting from the unique structural features, the resultant SiOx/C microspheres demonstrate high capacity and outstanding cyclability. Specifically, a reversible capacity of 999 mA h g−1 can be achieved at 100 mA g−1, retaining 853 mA h g−1 after 150 cycles. At 500 mA g−1, the SiOx/C delivers a specific capacity of 689 mA h g−1 and maintains 91.0% of the capacity after 400 cycles. SiOx/C//LiFePO4 full cells are also assembled, leading to an energy density of ~ 372 W h kg−1 based on the total mass of active materials. This work sheds light on the rational design of high-performance SiOx based anode materials for lithium-ion batteries.