Supercritical-Assisted Ball-Milling Synthesis of Multicomponent Si/Fe₃O₄/C Composites for Outstanding Lithium-Storage Capability

Abstract

Attributed to high theoretical capacity and abundant reserves, Si/C anodes have been commercialized in lithium-ion batteries (LIBs). However, the shortcomings of poor interfacial compatibility, low rate performance, and bad stability remain to be overcome. In this paper, a facile method for the synthesis of silicon/iron oxide/carbon (Si/Fe3O4/C) composites by ball-milling in a supercritical carbon dioxide (scCO2) fluid medium is proposed. This method utilizes the diffusion characteristics, extremely low viscosity, and excellent mass transfer properties of supercritical fluids. Under the infiltration of an scCO2 fluid, mesophase carbon microspheres (MCMB) are exfoliated into graphite flakes and achieve good interfacial fusion with silicon and Prussian blue during ball-milling. The Prussian blue is transformed into Fe3O4 by subsequent heat treatment under a nitrogen atmosphere, and Fe3O4 introduced in this way enhances the lithium-storage capacity, cycling stability, and rate performance significantly of Si/C anodes. As an anode for LIBs, the reversible capacity of Si/Fe3O4/C reaches 1363 mA h g–1 after 600 cycles at 1 A g–1. This study provides an idea for the design and fabrication of Si-based anode materials with high capacity and long cycle life.

Facile Synthesis of Laminated Si@C–Fe3O4 Composite from Exfoliation of Zintl Phase: A Promising Lithium Battery Anode with Superior Rate Capability and Cycling Stability

“…Lithium-ion batteries (LIBs) have been widely employed in consumer devices and electric cars due to high energy density, high cycle stability, and extended endurance. With the fast expansion of global energy storage, LIBs are expected to be one of the primary energy source technologies in the future. − Currently, graphite-based anodes for LIBs dominate commercially with their excellent cycling performance, but the low theoretical capacity of 372 mA h g –1 severely restricts potential large-scale energy storage applications. − Silicon (Si) anode is a promising alternative material because of the high theoretical capacity of 3579 mA h g –1 (Li 15 Si 4 ), low voltage plateau, abundant natural resources, and environmental friendliness. − However, the quick capacity degradation would come from the extreme volume expansion of Si upon cycling, which would destabilize the solid electrolyte interface (SEI) layer. − Pure Si is a semiconductor material with a low electronic conductivity and ionic diffusion coefficient, which are the primary causes of the poor cycle stability and quick charging capability …”