Dissolution-regrowth synthesis of SiO2 nanoplates and embedment into two carbon shells for enhanced lithium-ion storage

In this work, SiO2 nanoplates with opened macroporous structure on carbon layer (C-mSiO2) have been obtained by dissolving and subsequent regrowing the outer solid SiO2 layer of the aerosol-based C-SiO2 double-shell hollow spheres. Subsequently, triple-shell C-mSiO2-C hollow spheres were successfully prepared after coating the CmSiO2 templates by the carbon layer from the carbonization of sucrose. When being applied as the anodematerial for lithium-ion batteries, the C-mSiO2-C triple-shell hollow spheres deliver a high capacity of 501 mA·h·g-1 after 100 cycles at 500mA·g-1 (based on the total mass of silica and the two carbon shells), which is higher than those of C-mSiO2 (391 mA·h·g-1) spheres with an outer porous SiO2 layer, C-SiO2-C (370 mA·h·g-1) hollow spheres with a middle solid SiO2 layer, and C-SiO2 (319.8 mA·h·g-1) spheres with an outer solid SiO2 layer. In addition,the battery still delivers a high capacity of 403 mA·h·g-1 at a current density of 1000 mA·g-1 after 400 cycles.The good electrochemical performance can be attributed to the high surface area (246.7m2·g-1) andpore volume (0.441 cm3·g-1) of the anodematerials, as well as the unique structure of the outer and inner carbon layer which not only enhances electrical conductivity, structural stability, but buffers volume change of the intermediate SiO2 layer during repeated charge–discharge processes. Furthermore, the SiO2 nanoplates with opened macroporous structure facilitate the electrolyte transport and electrochemical reaction.