<i>In Situ</i> Synthesis of VO<sub>2</sub> Embedded in Graphite/Si as a High Performance Anode for Lithium-Ion Batteries

Abstract

To buffer the volume changes of silicon-based anode material and stabilize the solid-electrolyte-interface (SEI) layer formed in the electrolyte, a core-shell structure with VO2 coating is newly designed. In this composite, the pitch modified spherical graphite serves as a core, and the Si particles are uniformly dispersed on its surface, then the VO2 is synthesized in situ. The modified graphite/Si/VO2 (Si@G@V) anode exhibits a reversible capacity of 1247 mAh g-1 at the current density of 0.1 A g-1 after 50 cycles, obtain a capacity retention of ~99%. The rate capability of ~320 mAh g-1 at the current density of 10 A g-1 is also obtained. The excellent cyclic stability and superior rate performance mainly attributed to the uniform dispersion of Si particles in the pitch modified spherical graphite, the core-shell structure of the material as well as the in-situ synthesis of VO2. This simple synthesis process is of great significance to reduce the reunion and constrain the volume changes of silicon.