Modifiable dimensionality of aggregates of silicon to optimize the volume effect for lithium storage

Abstract

Si has been considered as one of the most promising anode candidates for lithium-ion batteries (LIBs). Nonetheless, the intrinsic defects of low conductivity and tremendous volume change greatly restrict its practical use in energy-storage applications. The design of aggregations from Si building blocks open an efficient means to further improve its electrical properties. Herein, zero-dimensional (0D) Si nanosphere, 2D macroporous nanonetworks of Si-Graphene (SGR) consisting of tiny silicon nanodots, and 3D nanocages-liked SGR have been designed and synthesized. For the first time, chemomechanical modeling of stress distribution of diverse aggregations and the aggregation effect on the lithium storage property have been systematically studied. For 2D SGR, the macropores structure between the GR and Si can stabilize solid electrolyte interface (SEI) layer and offer an appropriate buffer space for its freely expanding. As a result, electrochemical performance of the 2D SGR was superior to the 0D and 3D. Besides, the conversion reaction mechanisms and structural evolution of the as prepared Si anodes were investigated via the ex-situ XPS, EIS, SEM, and TEM. This work provides a valuable guidance to develop high-performance LIBs for practical applications.