熔盐电脱氧制多晶硅过程电流效率的影响因素

Influence Factors of Current Efficiency in Polysilicon Production Directly by Molten Salt Electrolysis

电流效率是熔盐直接电解脱氧制备多晶硅的一项重要指标,它涉及到电解槽的产量和电耗。如何提高熔盐电解的电流效率对多晶硅的单位时间产量、降低单位电耗等具有重要意义。采用CaCl2为电解质、SiO2粉末压制片为阴极及自制石墨棒为阳极进行了实验研究。在具体实验中测定了制备多晶硅过程中电流效率随电解时间、温度、电流密度及电极间距的变化关系。结果表明,当电解时间为6～10h、电解温度为800～900℃、电流密度为0.78～1.20A/cm2、电极间距为4～7cm时,电解效率较高。

The current efficiency is a key factor to affect the output and power consumption of elemental silicon production by molten salt electrolysis. It is of great significance for main economic and technical indexes to improve unit output and reduce the unit power consumption, etc. in the design of electrolysis tank. The system consisting of CaCl2 electrolyte and SiO2 powder pressing piece as the cathode is used in the experiment. The influences of electrolytic temperature, current density of cathode and distance between the poles upon the current efficiency and electrolytic time are investigated. The results show that when electrolytic time is 6- 10h, the reaction temperature is 800- 900℃, current density of cathode is 0. 78-1.20A/cm^2, and distance between poles is 4-7cm, the current efficiency is at the highest point in electrolysis