Core-shell structured SiOx@C with controllable mesopores as anode materials for lithium-ion batteries

The high-capacity silicon oxide (SiOx) is a promising anode candidate for lithium-ion batteries (LIBs), but the huge volume expansion during the cycle severely limits their practical application. Mesoporous SiOx is widely investigated as an effective solution due to the self-buffering inner-space. Nevertheless, both excessive and deficient inner-space have bad impacts on the anode material, so exploring a suitable pore volume is the top priority. In this work, an impressive and novel approach has been developed to prepare SiOx@C core-shell microspheres with different mesopores of SiOx. Vinyl-SiO2 nanoparticles are gestated in the framework of sulfonated polystyrene (SCLPS) microspheres to form the vinyl-SiO2/SCLPS composites by vinyltriethoxysilane as the silicon source and in-suit catalyzed by SCLPS. Afterwards, the vinyl-SiO2/SCLPS are covered by resorcinol/formaldehyde polymer, and then the core-shell microspheres are carbonized to prepare SiOx@C. The inner pore space of SiOx can be controlled by adjusting the cross-linking degrees (CLDs) of the SCLPS microspheres. After comparison, SiOx-6@C with the most suitable porous structure is selected, which exhibits a large reversible capacity (761 mAh g(-1) at 100 mA g(-1)) and acceptable cycling capacity (534 mAh g(-1) after 150 cycles). This work provides novel insights on exploring an appropriate inner-space to overcome the challenge of volume expansion.