Investigating the impact of preparation routes on the properties of copper-decorated silicon particles as anode materials for lithium-ion batteries

In recent years, the calendar life of Si has been recognized as a significant issue that must be addressed prior to technology deployment: The carbon conductive additive is a potential source of parasitic side reactions. However, carbon remains essential due to the low electronic conductivity of Si. In this study, we investigate the use of Cu as a conductive additive and potential alternative to carbon. Some Cu-decorated silicon particles (Si^Cu) were prepared using physical vapor deposition (PVD) via sputtering and high-energy milling. Other Si^Cu particles were prepared by using a solution method and examined briefly. The milling method caused Cu to appear as island-like features on the Si surface, whereas the PVD method initially produced similar island-like features that gradually developed into a continuous coating around the Si as sputtering time increased. Electrodes fabricated from Si^Cu exhibited lower overall resistivity, demonstrating the beneficial effect of Cu in improving electronic percolation through the electrode. Electrochemical tests showed that the milled Si^Cu exhibited higher capacity retention, improved rate capability, and lower overpotential. Furthermore, Si^Cu coupled with an NMC811 cathode exhibited lower leakage currents compared with the baseline silicon, indicating that incorporating Cu provided an additional advantage of minimizing parasitic currents in the cells.