Designing a simple polymerisation route for homogeneous SiOx/C spheres as a lithium-ion battery anode

Abstract

High-performance SiO_x/C composites are currently one of the potential anodes for practical lithium-ion batteries. However, the dispersion of carbon in previous SiO_x/C composites is usually uneven at the microscopic scale, where the anisotropic volume expansion generates continuous attenuation of coulombic efficiency in long-term cycling, resulting in a poor cycling performance. In the research reported here, the monodisperse SiO_x/C spheres with a size of 200–1000 nm are prepared by a simple chemical polymerisation combined with high-temperature carbonisation. 3-Aminopropyltriethoxysilane and glutaraldehyde are selected as the silicon and carbon sources to form the spherical polymer by an aldimine condensation reaction. The organic carbon in the precursor is transformed in situ into amorphous carbon, which is uniformly located in the Si–O–Si framework at the ultrafine nanoscale. Because of the unique structural nature, the synthesised SiO_x/C spheres demonstrate a long service lifespan together with a high coulombic efficiency. This work provides a practical design for reliable SiO_x/C anodes.