Electrochemical deposition of silicon from organic electrolytes

Fig. 3: Linear sweep voltammograms of 0.5 M SiCl4 in propylene carbonate based electrolyte (ν = 10 mV s-1). Inset: SEM micrographs of the resulting layers from the deposition at -1.7 V for 2 h on copper (a) and at -1.88 V for 2 h on nickel (b)
Parameters for the electrodeposition of silicon
Fig. 4: Chronoamperomograms of copper and nickel in [BMP] [TFSI] and propylene carbonate and of TiO2 nanotubes and copper foam in [BMP][TFSI]. The concentration of the precursor is 0.5 M, respectively, except for the TiO2 nanotubes (0.1 M). The applied potentials are -1.7 V (a), -1.5 V (b), -1.7 V (c), -1.9 V (d), and -1.9 V (e). The inset shows a more detailed view of the I-t transients
Fig. 5: SEM micrographs of the titanium foils anodized in glycerol with a 2 wt% H2O and 0.5wt% NH4F at 40 V – 75 min. Electrochemically reduced TiO2-NTs in KOH electrolyte (a) and silicon coated NTs (b)

Electrochemical reduction of silicon from SiCl₄ in 1-butyl-1-metyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [BMP][TFSI] and in propylene carbonate (PC) with SiCl₄ as a precursor is performed at room temperature. The process is studied by means of Linear Sweep Voltammetry and chronoamperometry. The results exhibit considerable differences during the silicon deposition for copper and nickel. Scanning Electron Microscopy (SEM) of the layers shows a rough surface morphology. The composition of Si deposit is confirmed by Energy Dispersive X-ray analysis (EDX). Furthermore, the deposition of silicon onto TiO₂ nanotubes is discussed. In conclusion, a method of recycling the used ionic liquid by a simple extraction procedure is presented.

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