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.
Keywords: Si particles; anode materials; copper coating; in situ electroless deposition; lithium-ion batteries.