In Situ Copper Coating on Silicon Particles Enables Long Durable Anodes in Lithium-Ion Batteries

Addressing the significant obstacles of volume expansion and inadequate electronic conductivity in silicon-based anode materials during lithiation is crucial for achieving a long durable life in lithium-ion batteries. Herein, a high-strength copper-based metal shell is coated in situ onto silicon materials through a chemical combination of copper citrate and Si-H bonds and subsequent heat treatment. The formed Cu and Cu₃Si shell effectively mitigates the mechanical stress induced by volume expansion during lithiation, strengthens the connection with the copper substrate, and facilitates electron transfer and Li⁺ diffusion kinetics. Consequently, the composite exhibits a reversible specific capacity of 1359 mA h g^-1 at 0.5 A g^-1 and maintains a specific capacity of 837 mA h g^-1 and an 83.5% capacity retention after 400 cycles at 1 A g^-1, surpassing similar reports on electrochemical stability. This facile copper plating technique on silicon surfaces may be used to prepare high-performance silicon-based anodes or functional composites in other fields.