Interface Engineering of Cu-Modified Silicon/Graphite Anode for High-Performance Lithium-Ion Batteries

Silicon/carbon composites have emerged as a promising avenue for overcoming the energy density limitations of lithium-ion batteries due to their high capacity and low cost. Nevertheless, their practical application is severely hindered by intrinsic challenges, including poor electrical conductivity, substantial volume expansion during cycling, and an unstable solid electrolyte interphase (SEI). To address these issues, we first develop a copper-modified silicon-graphite composite (Cu@Si/Gr) via a facile disproportionation reaction combined with a ball milling strategy. The incorporation of copper not only significantly enhances the electrical conductivity of the material but also promotes the formation of a high-quality LiF-rich SEI layer during cycling. Electrochemical tests demonstrate that the Cu@Si/Gr anode exhibits markedly improved cycling stability, with a capacity retention of 61.1% after 200 cycles at a high current density of 2 A g –1, substantially outperforming the unmodified Si/Gr anode. Moreover, full cells assembled with the Cu@Si/Gr anode and LiFePO 4 (LFP) cathode also deliver exceptional cycling performance, maintaining 95.9% capacity retention after 80 cycles at 1 C. This work offers a scalable and efficient strategy for constructing high-performance silicon-based anodes and provides valuable insights into interface engineering for advanced lithium-ion batteries.