Deciphering the effect of the heat treatment on the electrodeposited silicon anode for Li-ion batteries

Abstract

In this study, we report a facile way to improve the stability of electroplated Silicon (Si) electrodes through heat treatment. Electrodeposition of Si is carried out on a porous current collector followed by the heat treatment under an oxygen-free environment at 300 °C, 350 °C, and 400 °C. It is shown that as the heat treatment temperature increases, the cycling stability of the Si anode also dramatically improves. The Si electrode heat treated at 400 °C also keeps the quality of Si even after exposing the electrode to the air for up to 7 days which relieves the handling burden of Si in the ambient atmosphere. The striking difference allows the Si electrode heat treated at 400 °C to maintain its 77 % capacity even after exposure to air for one week. The outstanding electrochemical performance of the electrodeposited Si electrodes heat treated at various temperatures is characterized by thermogravimetric analysis coupled with fourier transform infrared spectroscopy (TGA-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) coupled with energy dispersive spectrometry and selected area electron diffraction (SAED), Raman spectroscopy, electrochemical cycling, and electrochemical impedance spectroscopy (EIS) techniques.