Preparation and electrochemical performance of copper foam-supported amorphous silicon thin films for rechargeable lithium-ion batteries

Abstract

Amorphous Si thin films, which have been deposited on copper foam by radio-frequency (rf) magnetron sputtering, are employed as anode materials of rechargeable lithium-ion batteries. The morphologies and structures of the as-prepared Si thin films are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Electrochemical performance of lithium-ion batteries with the as-prepared Si films as the anode materials is investigated by cyclic voltammetry and charge–discharge measurements. The results show that the electrode properties of the prepared amorphous Si films are greatly affected by the deposition temperature. The film electrode deposited at an optimum temperature of 300 °C can deliver a specific capacity of ∼2900 mAh/g and a coulombic efficiency above 95% at charge/discharge current density of 0.2 C after 30 cycles. The Li + diffusion coefficiency in copper foam-supported Si thin films is determined to be 2.36 × 10 −9 cm 2/s.