Scalable synthesis of porous SiFe@C composite with excellent lithium storage.

Abstract

Utilizing cost-effective raw materials to prepare high-performance silicon-based anode materials for lithium ion batteries (LIBs) is both challenging and attractive. Herein, a novel porous SiFe@C composite derived from low-cost ferrosilicon is prepared via a scalable three-step procedure, including suitable ball milling, partial etching and carbon layer coating. The novel pSiFe@C material integrates the advantages of the mesoporous structure, the partially retained FeSi2 conductive phase and a uniform carbon layer (12~16 nm), which can substantially alleviate the huge volume expansion effect in the repeated lithium ion insertion/extraction processes, effectively stabilize the SEI film and markedly enhance the overall electronic conductivity of the material. Benefiting from the rational structure, the obtained pSiFe@C hybrid material delivers a reversible capacity of 1162.1 mAh g-1 after 200 cycles at 500 mA g-1, with a higher initial coulombic efficiency of 82.30%. Meanwhile, it shows larger discharge capacities of 803.1 and 600.0 mAh g-1 after 500 cycles at 2 and 4 A g-1, respectively, manifesting an excellent electrochemical lithium storage. This work provides a bright prospect for the commercial production of high lithium storage capacity silicon-based anode materials for LIBs.