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

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 electroly-tic 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/cm2,and distance between poles is 4～7cm,the current efficiency is at the highest point in electrolysis.