Study into the possibility of silicon electrodeposition from a low-fluoride KCl-K2SiF6 melt

The possible use of the KCl-K2SiF6 molten system for silicon electrodeposition is considered. The kinetics of silicon electroreduction on glassy carbon in the KCl melt with the addition of 1 and 5 wt% K2SiF6 at 790 °C were studied using electroanalytical methods. It is demonstrated that the appearance of fluoride ions provides the required amount of silicon ions for silicon electrodeposition. Silicon electroreduction is shown to comprise a reversible single 4-electron process. According to the Berzins–Delahay equation for an electrochemically reversible process, the diffusion coefficient of electroactive ions calculated as equal to 4·10−6 cm2 s−1. The electrodeposition of silicon on a glassy carbon substrate was carried out in potentiostatic mode in the range of potentials from −0.1 to −0.25 V. As a result, silicon fibers with an average diameter of 200–300 nm were observed.