Improvement cycleability of core–shell silicon/copper composite electrodes for Li-ion batteries by using electroless deposition of copper on silicon powders

Abstract

In this work, core–shell Si/Cu composite powders were produced using an electroless process. The copper content on the surface of silicon powders was varied by using different concentrations of CuSO4 in the plating bath. The surface morphology of the produced Si/Cu composite powders was characterized using scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) was used to determine the elemental surface composition of the composites. X-ray diffraction (XRD) analysis was performed to investigate the structure of the Si/Cu composite powders. The discharge capacities and resistivity of the produced Si/Cu composite electrodes were studied using electrochemical impedance spectroscopy (EIS). The silicon/copper composite electrode produced using 40g/l CuSO4 exhibited the most stable capacity retention, and a discharge capacity of approximately 240mAh/g was obtained after 20cycles for this electrode. This study demonstrated that the conductivity of the electrodes was improved and the retention capacity of the Si/Cu composite electrodes was increased by increasing the copper content on the surface of silicon powders due to the buffering effect of copper against volume changes during the charging and discharging process.