Core-shell structured Si@Cu3Si-Cu nanoparticles coated by N-doped carbon as an enhanced capacity and high-rate anode for lithium-ion batteries

Abstract

• Both Cu 3 Si and NC of Si@Cu 3 Si-Cu@NC are formed during the carbonization of dopamine. • Core-double shell structured Si@Cu3Si-Cu@NC nanoparticles can effectively enhance the stability of Si-based anode. • Si@Cu3Si-Cu@NC nanoparticles shows a high performance (1105.5 mAh g -1 ) under 5A g -1 as LIB anode. Silicon based anode material is regarded as a promising candidate for Lithium ionic batteries (LIBs) due to its high theoretical specific capacity. Nevertheless, the capacity degradation triggered by high volume expansion has seriously hindered its application in LIBs. Herein, a novel structure of core-shell structured Si@Cu 3 Si-Cu nanoparticles coated by N-doped carbon (Si@Cu 3 Si-Cu@NC) is designed and synthesized via a two-step thermal reduction process. In this design, the copper shell and N-doped carbon can significantly limit and accommodate the volume change of Si during cycling. The in-situ formation of Cu 3 Si at the interface further improves the structural stability. The doping of N in carbon is conducive to the rapid transmission of electrons and ions as well as optimizes the electrochemical performance of the material. Therefore, the optimized Si@Cu 3 Si-Cu@NC nanocomposite anode shows prominent rate performance and delivers a reversible capacity of 1105.5 mAh g -1 after 100 cycles at a high current density of 5 A g -1 , which exhibits the great potential of the nanocomposite as high-performance LIBs anode material.