Porous Si-Cu₃ Si-Cu Microsphere@C Core-Shell Composites with Enhanced Electrochemical Lithium Storage

Low-cost Si-based anode materials with excellent electrochemical lithium storage present attractive prospects for lithium-ion batteries (LIBs). Herein, porous Si-Cu₃ Si-Cu microsphere@C composites are designed and prepared by means of an etching/electroless deposition and subsequent carbon coating. The composites show a core-shell structure, with a porous Si/Cu microsphere core surrounded by the N-doped carbon shell. The Cu and Cu₃ Si nanoparticles are embedded inside porous silicon microspheres, forming the porous Si/Cu microsphere core. The microstructure and lithium storage performance of porous Si-Cu₃ Si-Cu microsphere@C composites can be effectively tuned by changing electroless deposition time. The Si-Cu₃ Si-Cu microsphere@C composite prepared with 12 min electroless deposition delivers a reversible capacity of 627 mAh g^-1 after 200 cycles at 2 A g^-1 , showing an enhanced lithium storage ability. The superior lithium storage performance of the Si-Cu₃ Si-Cu microsphere@C composite can be ascribed to the improved electronic conductivity, enhanced mechanical stability, and better buffering against the large volume change in the repeated lithiation/delithiation processes.