Silicon (Si) is a promising candidate as an anode material for lithium-ion batteries. However, its application is hindered by poor cycling stability and rate-capability due to structural degradation, resulting from large volume changes during cyclic charging and discharging. In this paper, we report that uniform-sized Si@void@C nanoparticles can be prepared by magnesiothermic reduction of SiO₂@void@C. Si nanoparticles are in hollow carbon shells with a large void space between the carbon shell and particles. Thus, each Si particle can expand freely within the well-designed void space without destroying the outer carbon shell, and benefit the solid–electrolyte interphase film stabilization on the carbon shell. The new material shows a high capacity of 1598 mA h g⁻¹ at a current density of 1 A g⁻¹, a long cycle life of 1500 cycles with 85% capacity retention, and a high Coulombic efficiency of 99.6% as well, and might be a promising Si-based anode material for Li-ion battery applications.