Silicon Electrodeposition in Water-Soluble KF–KCl Molten Salt: Investigations on the Reduction of Si(IV) Ions

A new method for electroplating Si using a water-soluble KF–KCl molten salt electrolyte and high-purity gaseous SiCl 4 has been proposed. To gain a fundamental understanding of the process, the electrodeposition of Si from Si(IV) complex ions on a Ag electrode in a molten KF–KCl–K 2 SiF 6 system was investigated by cyclic voltammetry at 923 K. The reduction of Si(IV) ions to metallic Si was observed as a single 4-electron wave, which is explained by an E q E r (quasireversible-reversible electron transfer reactions) mechanism. The diffusion coefficient of the Si(IV) ions in the electrolyte was determined to be 3.2 × 10 −5 cm 2 s −1 at 923 K by chronoamperometry.