Carbon dioxide solid-phase embedding reaction of silicon-carbon nanoporous composites for lithium-ion batteries

SiO2 is one of the critical raw materials for preparing Si anode. The direct use of porous Si made from SiO2 in LIBs is challenging. Although carbon cladding can improve the cycling performance of Si anode materials made from SiO2, the surface coating cannot address the comminution inside the material during repeated volume deformation. For the first time, we prepared an in-situ doped Si/carbon anode material that uses SiO2 and CO2 as Si and carbon sources and Mg as the reduction medium (Mg2Si + CO2 -> MgO + Si + C). The in situ embedded carbon completes the nanosizing of Si (less than50 nm) and forms a three-dimensional (3-D) carbon network that enhances electrical conductivity and acts as a buffer layer. After 500 cycles at 0.5 A g-1, the discharge specific capacity is 912 mAh g-1, and the capacity still has 1487 mAh g-1 even at 4 A g-1. The simple method of preparing Si/carbon composite material in situ provides a new idea for modifying Si-based anode material and provides a valuable reference for carbon doping.

Automated summary

This study prepared an in-situ doped Si/carbon anode material using SiO2 and CO2 as raw materials, achieving nanosizing of silicon and construction of a 3D carbon network, which improved electrical conductivity and cycling performance of the battery. The simple preparation method provides a new idea for modifying silicon-based anode materials, offering valuable insights for further research on carbon doping.