The well-defined three-dimensional matrix of a micro-sized silicon/carbon composite promoting lithium-ion transportation†

Abstract

Micro-sized silicon is a promising anode material due to its high theoretical capacity and low cost. However, its bulk particle size poses a challenge during electrochemical cycling, and the long ion/electron transport paths within it limit the rate capability. Herein, we propose a structural engineering approach for establishing a well-defined three-dimensional (3D) micro-sized silicon/carbon matrix to achieve efficient omnidirectional ionic and electronic conductivity within micro-sized silicon and effectively mitigate the volume changes. The prepared materials, comprising ordered two-dimensional porous silicon nanosheets, offer direct two-dimensional electrolyte transport channels aligned parallel to the layer plane and porous channels oriented perpendicular to the layer plane. These well-defined omnidirectional pathways enable more efficient electrolyte mass transport than the disordered paths within the traditional 3D porous silicon anodes. A robust carbon shell, securely bonded to silicon through dual covalent bonding, effectively shields these pathways, buffering the volume changes and offering an electronically conductive 3D carbon network.