Rational design of void-involved Si@TiO2 nanospheres as high-performance anode material for lithium-ion batteries.

A unique core-shell structure of silicon@titania (Si@TiO2) composite with silicon nanoparticles encapsulated in TiO2 hollow spheres is synthesized by a simple hydrolysis method combined with magnesiothermic reduction method. It is found that the TiO2 shell is effective for improving the electrical conductivity and structural stability. More importantly, the well-designed nanostructure with enough empty space would accommodate the volume change of silicon during the cycling. Reversible capacities of 1911.1 and 795 mAh g(-1) can be obtained at 0.05 C and a high current rate of 1 C, respectively. After 100 cycles at 0.1 C, the composite electrode still maintains a high capacity of 804 mAh g(-1). This excellent cycling stability and high-rate capability can be ascribed to the unique core-shell nanostructure and the synergistic effect between Si and TiO2.