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/Fe 3 O 4 /C) composites by ball-milling in a supercritical carbon dioxide (scCO 2 ) 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 scCO 2 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 Fe 3 O 4 by subsequent heat treatment under a nitrogen atmosphere, and Fe 3 O 4 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/Fe 3 O 4 /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.