Improved Lithium Storage Capability of Si Anode by Ball-Milling Produced Graphitic Carbon Sheet and Fe₃O₄ Nanoparticles

Silicon is considered the most promising material for anodes for the development of lithium-ion batteries (LIBs) due to its high theoretical capacity and natural abundance. However, the poor intrinsic conductivity and serious volume changes severely restrain the practical application. To address these issues, combining Si with carbon is confirmed as an effective strategy, but still suffers from uneven combination, poor interfacial contact and inferior electrochemical performance. Herein, Si@Fe₃O₄@C composites were synthesized by facile scalable ball-milling of nanosilicon, mesophase carbon microspheres (MCMB) and iron scurf from a stainless steel reactor. As compared to Si/C, the Si@Fe₃O₄@C composites exhibit much improved specific capacity, cycling stability and rate performance. The Fe₃O₄ nanoparticles not only help to boost the conductivity of Si but also accommodate their volume expansion during cycling. Consequently, the Si@Fe₃O₄@C anode delivers a reversible capacity of 1009 mA h g⁻¹ at 200 mA g⁻¹ after 110 cycles and 780.8 mA h g⁻¹ at 1 A g⁻¹ after 500 cycles. The method shows the merits of low cost, facile operation and easy industrial production for the synthesis of high-capacity Si anodes.