Carbon-Coated Mesoporous SiOx Using an Oil Templating As a High Capacity Anode Material for Lithium-Ion Battery

Si based anode materials for lithium-ion batteries have gained much attention due to its high theoretical capacity (3,580 mAhg^-1). However, Si anode materials have critical limit to commercial use because of poor cycle performance associated with severe volume changes during cycling. To solve this problem, various approaches have been suggested. In particular, porous structure of Si materials would be helpful for improvement of cycle performance. In this work, C-coated mesoporous SiO_x nanoparticles were prepared as anode materials for lithium-ion batteries using a sol-gel reaction of Si precursor with oil templates. The hydrophobic oil, pore former, was uniformly distributed into the SiO_x precursor. After heat treatment under reducing atmosphere, the residual oil was contributed to form the carbon layer, which would be assisted to improve electrical conductivity of active materials, on the surface of SiO_x matrix. The C-coated mesoporous SiO_x nanoparticles showed a reversible capacity of 730 mAhg^-1 at current density of 200 mAg^-1 with stable cycle performance over 100 cycles and high rate capabilities. The microstructure and electrochemical properties of the C-coated mesoporous SiO_x nanoparticles will be discussed in more detail.