Mechanochemically Reduced SiO₂ by Ti Incorporation as Lithium Storage Materials

This study presents a simple and effective method of reducing amorphous silica (a-SiO₂) with Ti metal through high-energy mechanical milling for improving its reactivity when used as an anode material in lithium-ion batteries. Through thermodynamic calculations, it is determined that Ti metal can easily take oxygen atoms from a-SiO₂ by forming a thermodynamically stable SiO_2-x/TiO_x composite, meaning that electrochemically inactive a-SiO₂ is partially reduced by the addition of Ti metal powder during milling. This mechanically reduced SiO_2-x/TiO_x composite anode exhibits a greatly improved electrochemical reactivity, with a reversible capacity of more than 700mAh g^-1 and excellent cycle performance over 100 cycles. Furthermore, an enhancement in the mechanical and thermal stability of the composite during cycling can be mainly attributed to the insitu formation of the SiO_2-x/TiO_x phase. These findings provide new insight into the rational design of robust, high-capacity, Si-based anode materials, as well as their reaction mechanism.