Design of SiO _x /TiO₂@C hierarchical structure for efficient lithium storage

The large volume expansion effect and unstable solid electrolyte interface films of SiO _x -based anode materials have hindered their commercial development. It has been shown that composite doping is a general strategy to solve critical problems. In this study, TiO₂-doped core-shell SiO _x /TiO₂@C composites were created using the sol-gel method. On the one hand, the uniformly dispersed TiO₂ nanoparticles can alleviate the volume expansion of the SiO _x active material during the lithiation process. On the other hand, they can react with Li⁺ to form Li _x TiO₂, thereby increasing the ion diffusion rate in the composite material. The outer carbon shell acts as a protective layer that not only alleviates the volume expansion of the composite, but also improve the electron migration rate of the composite. The prepared SiO _x /TiO₂@C composite has a reversible capacity of 828.2 mA h g⁻¹ (0.2 A g⁻¹ 100 cycles). After 500 cycles, it still maintains a reversible capacity of 500 mA h g⁻¹ even at a high current density of 2 A g⁻¹. These findings suggest that SiO _x /TiO₂@C composites have a bright future in applications.