Solubility-Difference-Driven Strategy for Constructing Core–Shell Structure Si@C Anodes: Ammonia-Assisted Carbon Shell Embedded with Copper Nanoparticles

Compounding with carbon materials is an effective strategy to mitigate the intrinsic challenges of silicon anodes, particularly their severe volume variation and poor electrical conductivity, thereby demonstrating significant potential for commercial lithium-ion battery applications. In this study, a solubility-difference-driven approach is proposed for constructing core-shell structured Si@C anodes. Utilizing the distinct solubility difference of poly(vinyl alcohol) and basic copper carbonate in ammonia-water and ethanol, a uniform carbon shell embedded with copper nanoparticles is successfully formed on the silicon surface (Si@C-3). The optimized Si@C-3 anode exhibits improved electrochemical performance, delivering a high reversible capacity of 1346.1 mAh g^-1 at 0.2 A g^-1 after 150 cycles. Moreover, the material also exhibits cyclic stability at a higher current density of 2 A g^-1, retaining a capacity of 559.1 mAh g^-1 after 300 cycles. Notably, even under high-rate conditions of 6 A g^-1, the anode maintains a capacity of 465.8 mAh g^-1. These improved electrochemical performances are attributed to the stable electrode structure enabled by the well-coated carbon shell and enhanced electrode kinetic processes facilitated by the incorporated copper nanoparticles. This solubility-difference-driven strategy provides a feasible and scalable pathway for developing high-performance Si/C composite anodes for advanced lithium-ion batteries.