Preparation of a Novel Fluorosilicate Salt for Electrodeposition of Silicon at Low Temperature

A novel fluorosilicate salt, 1-ethyl-3-methylimidazolium hexafluorosilicate ((EMI)2SiF6), was prepared by the reaction of EMICl and hexafluorosilicate acid aqueous solution. A transparent thin film containing silicon was deposited on a silver electrode by potentiostatic electrolysis in molten (EMI)2SiF6 at 90°C. The film was reactive against water to form silicon dioxide. (EMI)2SiF6 was found to dissolve in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfone)imide (EMITFSI) room temperature molten salt. The same thin film was also obtained on a silver electrode by potentiostatic electrolysis in EMITFSI containing (EMI)2SiF6 at room temperature.