Magnesiothermic reduction improved route to high-yield synthesis of interconnected porous Si@C networks anode of lithium ions batteries

Abstract

Silicon (Si) based materials has been envisaged as a promising anode material for the next-generation high energy-density lithium-ion batteries (LIBs) thanks to its ultrahigh specific capacity. The development of reliable Si anode yet faces challenges of how to explore a simple, convenient and controllable synthetic route of Si composite anode with high conductivity and favorable structure. Herein, we report a newly synthetic route by extending the well-known Mg-thermal reduction method for the high-yield fabrication of three-dimensional (3D) porous Si/C nano-architectures (p-Si@C) featuring interconnected conductive networks and hierarchical mesoporous structure, endowing it with favorable properties and structure as anode of lithium-ions batteries (LIBs). Comprehensive characterization via various techniques coupling with density functional theory calculations demonstrates the as-prepared p-Si@C nano-architectures are favorable for forming stable solid-electrolyte interface (SEI), facilitating Li+ transport and electrons transfer, and mitigating the volume expansion effect upon for Li+ storage. As such, the Si@C nano-architectures not only exhibit high reversible capacity of 1078.68 mAh g−1 and impressively high cycling stability over 500 cycles at 1 A g−1 but also keep a quite attractive capacity retention rate of 47.9% even increasing rate to 10 A g−1. The feasibility of its practical application has been demonstrated by a lithium-ion full battery with the commercial lithium iron phosphate (LFP) as cathode, which delivers a stable reversible capacity of 124.4 mA g−1 and boasting high energy density of 381.61 Wh kg−1 at 0.2 C based on total mass of active material of the cathode and anode.