On the Stability of the Concentration of Silicon Ions in LiCl–KCl-CsCl-K2SiF6 Melts During Electrolysis

In this work, the interaction of K₂SiF₆ with LiCl–KCl-CsCl chloride melts was studied using cyclic voltammetry and atomic emission spectroscopy analysis, depending on their cationic composition in the temperature range from 550 to 665 °C. It has been determined that an increase in the CsCl/LiCl ratio leads to a decrease in the rate of decomposition of the K₂SiF₆ additive due to the formation of compounds with greater stability due to the replacement of the cation and the predominance of the corresponding reactions. Based on the results of ICP-AES, a decrease in the concentration of silicon ions in the melt during electrolysis was detected, and its final values in the melts at the end of the 12-h exposure were determined. During electrolysis, the silicon concentration also decreases, and in the case of a short electrolysis duration (up to 4 h), it is possible to maintain a sufficient concentration to be carried out without introducing additional K₂SiF₆ in the process. The optimal composition for electrodeposition was also determined, and it was found that a high LiCl content in the melt leads to the formation of lithium fluoride and its inclusion in the deposit.