Highly Si Loading on Three-Dimensional Carbon Skeleton Via Cvd Method for a Stable Si-C Composite Anode

Abstract

The chemical vapor deposition (CVD) based Si-C composite anode materials attract worldwide attention due to their potential to solve the notorious problems of volume expansion and electrode instability of Si-based anode materials. Herein, a high-strength, high-flexibility, and high-conductivity carbon skeleton composed of graphene and carbon nanotubes (CNTs) was constructed via spray-drying to load Si using the CVD process. The unique electrical, mechanical, and porous properties of the composite carbon skeleton jointly contribute to the excellent electrochemical performance of the composite anode. Even without the carbon coating, this composite possesses a high capacity of 1154 mAh g-1 and a capacity retention of 98.7% after 150 cycles at 0.5 A g-1. Plasma enhanced chemical vapor deposition (PECVD) was used to deposit an ultrathin onion-like carbon layer on the composite, further enhancing its cyclic stability (802 mAh g-1 @1 A g-1 with a capacity retention of 90.7% after 500 cycles). The great potential of the composite anode was further verified by the full cell with the commercial cathode of NCM811, which exhibited a high energy density of 430 Wh kg-1 and an impressive capacity retention of 72.0% after 150 cycles at 1 C.

Keywords: CVD, Spray-drying, Graphene, Carbon skeleton, Lithium-ion battery