Morphology Change Of Si Deposit In Molten Salt Electrorefining

The effects of processing parameters on the morphology change in a Si deposit recovered by means of molten salt electrorefining are evaluated using electrochemical techniques such as cyclic voltammetry and chronopotentiometry at 800°C. It was found that concentration of K₂SiF₆ and current density were important parameters in determining deposit size. Higher concentrations of K₂SiF₆ were effective in coarsening the silicon deposit and decreasing the cell potential. Silicon nanofiber was recovered at 5 wt% of K₂SiF₆ whereas dense particles were prepared at 30 and 50 wt% of K₂SiF₆. The morphology of the Si deposit was determined by the concentration of Si in the electrolyte which is related to the formation of crystal and growth of Si. The formation mechanism of the Si deposit was interpreted by using high resolution TEM as well as electrochemical properties.