Core–shell structured monodisperse carbon-rich SiO _1.31 C _1.46 H _0.81 ceramic spheres as anodes for high-capacity lithium-ion batteries

Abstract SiOC ceramic material is a promising anode material for lithium-ion batteries. However, due to its intrinsically low electronic conductivity, it often suffers from a much lower specific capacity than the theoretical value, poor rate capability and serious potential hysteresis. In this paper, we report a core–shell structured monodisperse carbon-rich SiO _1.31 C _1.46 H _0.81 submicron ceramic sphere with a free carbon content of 13.7 wt%, which is synthesized by directly annealing polysiloxane spheres derived from vinyltrimethoxysilane without adding external carbon resources. The SiO _1.31 C _1.46 H _0.81 sphere has a unique microstructure, the core of which is organically assembled by large amounts of SiO _1.31 C _1.46 H _0.81 primary particles of less than 20 nm and coated by a shell of 20–50 nm. As anodes for lithium-ion batteries, it presents much higher reversible capacity, initial Coulomb efficiency (ICE) and rate performance than the SiOC-based ceramic materials reported in the literature to date. At 100 mA g ⁻¹ , its first reversible capacity and ICE reach ∼1107 mAh g ⁻¹ and 78.2%, respectively. At 1600 mA g ⁻¹ , its stable discharge capacity is still as high as 610 mAh g ⁻¹ . The excellent electrochemical performance is attributed to the moderate composition, spherical morphology and unique microstructure of the synthesized material.