Design of SiOx/TiO2@C hierarchical structure for efficient lithium storage.

ABSTRACT

The large volume expansion effect and unstable solid electrolyte interface films of SiOx-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 SiOx/TiO2@C composites were created using the sol-gel method. On the one hand, the uniformly dispersed TiO2nanoparticles can alleviate the volume expansion of the SiOxactive material during the lithiation process. On the other hand, they can react with Li+to form LixTiO2, 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 SiOx/TiO2@C composite has a reversible capacity of 828.2 mA h g-1(0.2 A g-1100 cycles). After 500 cycles, it still maintains a reversible capacity of 500 mA h g-1even at a high current density of 2 A g-1. These findings suggest that SiOx/TiO2@C composites have a bright future in applications.