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

Abstract

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.