Volume expansion restriction by TiO 2 structural unit in silicon anodes with yolk–shell structure for lithium-ion batteries

Silicon (Si), due to its high theoretical capacity and abundant resources, has emerged as a potential anode material for lithium-ion batteries(LIBs). However, it suffers from intrinsic capacity decay and rapid degradation, coupled with huge volume expansion that leads to unstable growth of solid electrolyte interface (SEI). Here, we present a straightforward method to construct YS-Si/SiO₂-Ti@C materials with yolk-shell (YS) structure by reducing titanium silicalite-1 (TS-1) with magnesium and altering depositing carbon sequence. Besides, the intermediate space which can effectively accommodate the expansion of internal silicon nanoparticles. TiO₂ structural units anchored in the silica alleviate stress-strain in the Si nanoparticles to enhance the cycling stability. The obtained YS-Si/SiO₂-Ti@C composites anode exhibits exceptional reversible capacity and cycling stability compared to YS-Si/SiO₂@C (without TiO₂) and commercial Si electrodes. Notably, the YS-Si/SiO₂-Ti@C composite anode achieves a high specific capacity (1290 mAh g^-1 after 200 cycles at 0.8 A g^-1) and a stable SEI film. Specially, the YS-Si/SiO₂-Ti@C electrode delivers impressive capacity of 1590, 1521, 1222, 646 mAh g⁻¹ at 0.8, 2, 4, and 8 A g^-1, respectively. This study paves an avenue for addressing challenge of drastic volume change in silicon during lithiation/delithiation process to improve cycling stability of LIBs.