Silicon Electrodeposition from Low-Melting LiCl–KCl–CsCl Melts

The possibility of silicon electrodeposition using LiCl–KCl–CsCl–LiF–K 2 SiF 6 and LiCl–KCl–CsCl–K 2 SiF 6 electrolytes is investigated. The kinetics of silicon electrowinning on glassy carbon at a temperature of 480–550°C is studied by voltammetry. Silicon electrodeposition under experimental conditions is found to proceed in one four-electron stage and to be not electrochemically reversible. The results of electrochemical measurements are used to estimate the diffusion coefficients of silicon ions in LiCl–KCl–CsCl melts (3.2 × 10 –5 , 7.2 × 10 –6 cm 2 /s at temperatures of 480, 550°C, respectively) and select conditions for silicon electrodeposition. The structure and morphology of the silicon deposits formed under potentiostatic conditions are investigated. A decrease in the lithium chloride concentration in the melt is shown to result in silicon deposits in the form of dendrites and fibers.